ccm/sff-papers · Datasets at Hugging Face

['Dai, K.', 'Shaw, L.']

2019-10-24T17:56:37Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77410', 'http://dx.doi.org/10.26153/tsw/4499']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Densification

Preheating Effects on Multiple Material Laser Densification

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1e3e2522-f98a-4cfa-8e4b-9d04b9022317/download

null

A 3-dimensional thermomechanical model has been developed to study laser powder densification of multiple materials in the multi-materials laser densification (MMLD) process. Thermal and mechanical properties of the materials are porosity- and temperature-dependent. In particular, the effect of the chamber preheating on residual stresses and warping of the part fabricated has been investigated. It is found that the chamber preheating can reduce warping and residual stresses of the laser-processed part. Furthermore, the extent of the preheating effect depends on the laser-scanning pattern. Implications of the simulation result on MMLD have been discussed.

The authors gratefully acknowledge financial support provided by the National Science Foundation under Grant No: DMI-9908249.

null

['Saint John, David B.', 'Joshi, Sanjay B.', 'Simpson, Timothy W.', 'Qu, Meng', 'Rowatt, John David', 'Lou, Yucun']

2021-10-26T20:21:52Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89576

eng

2016 International Solid Freeform Fabrication Symposium

Open

['laser-based powder bed fusion', 'additive manufacturing', 'Inconel 718', 'feedstock powders', 'build location', 'variability']

A Preliminary Examination of Variability Due to Build Location and Powder Feedstock in Additive Manufacture of Inconel 718 using Laser-Based Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/40e8a042-28a1-42e6-b7f6-1698585c81ec/download

University of Texas at Austin

The production of metallic parts by additive manufacturing (AM) is of significant interest to industry, but in the absence of standards, practical design considerations for manufacturing engineers are not widely known. Within the context of powder bed fusion (PBF), many unknowns persist regarding variations in part quality due to part location on the build plate, process consistency, feedstock supplier, and machine manufacturer. In this paper, we investigate the mechanical property variance across the build platform and document the successful use of feedstock powders obtained from several suppliers for the manufacture of Inconel 718 tensile and Charpy specimens, built on an EOS M280 laser-based powder bed fusion system. Particular emphasis is placed on describing the manufacturing process design challenges encountered even for simple geometries. While many advocate that complexity is free when using AM, we find that AM can lead to expensive build failures given the current state of manufacturing process knowledge and that design for additive manufacture is required for successful application of AM techniques.

null

['Levy, Richard A.', 'Guduri, Sashidhar', 'Crawford, Richard H.']

2018-04-19T18:02:18Z

1992

Mechanical Engineering

doi:10.15781/T2NK36N7B

http://hdl.handle.net/2152/64396

eng

1992 International Solid Freeform Fabrication Symposium

Open

['Department of Mechanical Engineering', 'computed tomographic data', 'CT data', 'Department of Mechanical Engineering', 'Department of Radiology']

Preliminary Experience with Selective Laser Sintigrapbic (SLS) Models of the Human Temporal Bone

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ff1f7819-d86f-4401-aaa3-25070f1140c7/download

null

To assess the accuracy of three-dimensional models of the human temporal bone generated from computed tomographic (CT) data.

null

['Kumar, Pranav', 'Beck, Elizabeth', 'Das, Suman']

2019-11-15T16:20:58Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78421', 'http://dx.doi.org/10.26153/tsw/5508']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Preliminary

Preliminary Investigations on the Deposition of Fine Powders Through Miniature Hopper-Nozzles Applied to Multi-Material Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/630ff6b0-6dce-46a1-ac23-fa0a34b0276a/download

null

A concept for multi-material solid freeform fabrication is proposed to enable the fabrication of heterogeneous components. This concept features nozzles designed for depositing thin layers of multiple patterned materials followed by selective laser sintering for consolidation to desired densities. Although prior work on the design of small-scale nozzles for powder delivery is lacking, our design is guided by background theory for particle flow through hoppers. Experimental guidelines for the delivery of powders with particle sizes in the 10-125µm range through hopper-nozzle orifices with diameters in the 0.5-2mm range are presented. This is a preliminary investigation of particle flow behavior necessary for continuous mass flow rates under gravity, low gas pressure-assisted flow, and vibration-assisted flow conditions. As proof of concept, several patterned beds of single and multiple materials were deposited on an X-Y table. A simple model to predict the linewidth of lines deposited by gravity flow is presented.

null

['Niino, T.', 'Yamada, H.', 'Seki, S.']

2020-02-13T19:21:16Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79964', 'http://dx.doi.org/10.26153/tsw/6989']

eng

2004 International Solid Freeform Fabrication Symposium

Open

stereolithography

Preliminary Study for Transparentization of SLS Parts by Resin Infiltration

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a1c94be4-a646-40bb-ba65-2825450566e3/download

null

Since opacity of SLS processed parts are derived from random reflection and refraction at boundaries of refractive indices between the air and plastic, infiltration of resin that shares the same index with the plastic can increase transparency of the parts. In this paper, desirable characteristics for the infiltrant were investigated first, and transparentization test of SLS processed parts out of CastFormTM was carried out. The highest transmittance of 80% and the lowest haze of 55% were obtained. However, exact match of refractive indices of powder for SLS and infiltrant did not give the best transparency. The reasons were considered in discussions.

null

['Miyanaji, Hadi', 'Yang, Li', 'Zhang, Shanshan', 'Zandinejad, Amirali']

2021-10-13T20:04:11Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88774', 'http://dx.doi.org/10.26153/tsw/15708']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['dental porcelain', 'aluminous porcelain', 'graded structure', '3D printing']

A Preliminary Study of the Graded Dental Porcelain Ceramic Structures Fabricated via Binder Jetting 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/93f84829-aca1-46f3-9af9-1851b8869b6b/download

University of Texas at Austin

Dental porcelain is a common material used for various dental restoration structures including crowns, bridges and veneers. However, the current designs of all-ceramic porcelain restorations lack sufficient mechanical property controls, which results in increased failure rates. In this study, dental porcelain ceramics with graded compositions were fabricated by binder jetting 3D printing system in the attempt to actively control their mechanical performance. The graded structures were produced by two different fabrication routes, which are lamination stacking and continuous fabrication. In the lamination stacking route, porcelain laminates with different compositions were fabricated individually and stacked up for the sintering to form integrated structures with graded properties. In the continuous fabrication, samples with graded structure were printed continuously in the 3D printing machine. Microstructural evaluations with the samples demonstrated the feasibility of achieving good structural integrity for the dental porcelain parts fabricated by the continuous method.

null

['Fei, Guanghai', 'Wei, Tiwei', 'Shi, Qimin', 'Guo, Yongjian', 'Oprins, Herman', 'Yang, Shoufeng']

2021-11-30T20:29:15Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90537', 'http://dx.doi.org/10.26153/tsw/17456']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['hybrid manufacturing', 'electronics devices', 'stereolithography', 'adhesion', 'thermal reliability']

Preliminary Study on Hybrid Manufacturing of the Electronic-Mechanical Integrated Systems (EMIS) via the LCD Stereolithography Technology

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c8c147ce-d701-4882-bde8-ccef83a41d95/download

University of Texas at Austin

Compared to limited complexity capacity in traditional fabrication and assembly techniques, Additive Manufacturing (AM)-based hybrid fabrication is emerging in electronics industry for fabricating complex structures and simplifying the assembly steps. In this study, the fabrication process of the Electronic-Mechanical Integrated Systems (EMIS) is investigated, in which mechanical parts (gas/liquid chambers) were 3D printed directly on PCB substrate (the carrier of electronic devices). A mixture of resin with silica was used as printing feedstock, to reduce mismatch of thermal expansion coefficient (CTE) between the part and PCB. The silica loading of 60 vol% was appropriate to achieve a compromise between viscosity of the suspension and CTE. Adhesion forces between printed parts and PCBs were measured, showing a significant correlation with the PCB surface roughness. Thermal cycling test indicated that the tailored materials owned excellent CTE compatibility with PCB. Consequently, AM-based hybrid manufacturing is capable of fabricating protective/functional bodies for electronics.

null

['Raval, Jay K.', 'Kazi, Aamer A.', 'Guo, Xiangyu', 'Zvanut, Ryan', 'Lee, Chabum', 'Tai, Bruce L.']

2021-12-06T23:24:51Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90715', 'http://dx.doi.org/10.26153/tsw/17634']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['AM machinery', 'tool failure', 'surface finish', 'Ti-6Al-4V', 'additive manufacturing']

Preliminary Study on Machining of Additively Manufactured Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/32fc39b7-7610-4be4-8d11-17f886432998/download

University of Texas at Austin

Additively manufactured metals differ from their conventionally produced counterparts due to the inherent material inhomogeneity, porosity, and thermal stress induced by the process. These differences make the machining of additively manufactured metals more difficult and cause premature tool failure or unexpected surface finish at certain conditions. This study takes the first step to investigate and identify the causes of these issues, particularly for Ti-6Al-4V. Printed and wrought samples, as well as heat treatment effect, are compared in a dry cutting condition at a cutting speed of 90 m/min in terms of cutting power, vibration, temperature, and produced surface finish. The results show a lower cutting power and more vibration for as-printed Ti samples, indicating a less ductile microstructure and inclusion of pores. Heat treatment can eliminate these phenomena. There is no significant difference found in the produced surface finish at the current cutting condition.

null

['Yildirim, E.', 'Yin, X.', 'Guceri, S.', 'Sun, W.']

2020-02-27T19:50:50Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80098', 'http://dx.doi.org/10.26153/tsw/7119']

eng

2006 International Solid Freeform Fabrication Symposium

Open

single-walled carbon nanotubes

A Preliminary Study on Using Multi-Nozzle Polymer Deposition System to Fabricate Composite Alginate/Carbon Nanotube Tissue Scaffolds

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5693b5d8-64b5-4102-bfa8-73de52e96705/download

null

Three-dimensional composite alginate/single wall carbon nanotube (SWCNT) scaffolds encapsulated with endothelial cells were fabricated by a multi-nozzle biopolymer freeform deposition system. This system enables the converting of CAD designed scaffold pattern into process toolpaths and the use of computer control program to guide the nozzle deposition at spatial position for layered fabrication of 3D tissue scaffolds. The morphological, mechanical, structural and biological properties of as-fabricated scaffolds were characterized by optical microscope, SEM, Microtensile testing machine, Alamar Blue Assay, and Live-Dead Assay, respectively. The multi-nozzle deposition system demonstrated a highly efficient and effective process to build tissue scaffold or cell embedded constructs. Characterization results showed that the incorporation of SWCNT into alginate not only enhanced the mechanical strength of the scaffolds but also improved the cell affinity and the interaction with substrate. Further cell culture experimental results also showed that the incorporation of SWCNT in alginate enhanced endothelial cell proliferation compared with pure alginate scaffold.

null

['Bailey, Alta C.', 'Merriman, Abbey', 'Elliott, Amelia', 'Basti, Mufeed M,']

2021-10-28T14:51:17Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89656

eng

2016 International Solid Freeform Fabrication Symposium

Open

['part density', 'binder effect', 'nanoparticle effect', 'binder jetting']

Preliminary Testing of Nanoparticle Effectiveness in Binder Jetting Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e44a23fd-c1a3-4588-ad62-36e463205bc0/download

University of Texas at Austin

Binder jetting works by selectively depositing a binder with an inkjet print head into layers of powdered material. Compared with other metal Additive Manufacturing (AM) processes, binder jetting has significant potential for near-term adoption in manufacturing environments due to its reliability and throughput. The Achilles heel of binder jetting, however, is the inability to produce fully dense, single-alloy materials. The lack of density in printed binder jet parts is strictly dictated by the packing factor of the powder feedstock. Adding nanoparticles during printing will not only increase the part’s packing factor but may also serve as a sintering aid. This study focuses on the effect of both the binder and nanoparticles on the final part density. As an unintended consequence of high nanoparticle loading, printed parts underwent a significant increase in porosity during the curing process. This unintended consequence is the apparent result of the nanoparticles blocking the exit of the solvent vapor during the curing step. Additionally, nanoparticle use for densification is validated with SEM imagery.

null

['Crocker, James E.', 'Sun, Lianchao', 'Shaw, Leon L.', 'Marcus, Harris L.']

2019-02-26T20:15:31Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73494', 'http://dx.doi.org/10.26153/tsw/644']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['SALDVI', 'macro-component']

Preparation and Properties of In-Situ Devices Using the SALD and SALDVI Techniques

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7085d303-1e63-4204-b56d-0d67f00eed5e/download

null

One of the many advantages of Selective Area Laser Deposition (SALD) and Selective Area Laser Deposition Vapor Infiltration (SALDVI) is that they can be used to embed in-situ micro-sensors within macro-components. A single-point SiC/C thermocouple sensor embedded within a SiC macro-component and electrically insulated with silicon nitride layers has been demonstrated. In many applications, multi-point sensors within a single component are needed, e.g., in monitoring the temperature gradient and distribution at different positions. In this paper, multi-point thermocouple devices are demonstrated. The macro-component is a SiC bulk shape made by infiltrating vapor deposited silicon carbide into a silicon carbide powder bed using the SALDVI technique. Multiple SiC/C thermocouples are embedded in-situ in the SiC bulk shape using the SALD technique. The transient and steady state responses ofthe embedded thermocouples are compared to reference thermocouples probing the surfaces of the bulk shape.

null

['Regenfuss, P.', 'Streek, A.', 'Hartwig, L.', 'Klötzer, S.', 'Brabant, Th.', 'Horn, M.', 'Ebert, R.', 'Exner, H.']

2020-03-05T20:15:51Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80156', 'http://dx.doi.org/10.26153/tsw/7177']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Laser Micro Sintering

Principles of Laser Micro Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b52774c0-49c3-4e7f-807f-5ef422c2e6d1/download

null

Laser Micro Sintering was introduced to the international community of freeform fabrication engineers in 2003 and has since been employed for a variety of applications. It owes its unique features to certain effects of q-switched pulses that formerly had been considered detrimental in selective laser sintering. Besides sub-micrometer sized powders also materials with grain sizes of 1-10 micrometers can be sintered. Surface and morphology of the product are influenced by grain size and process environment. First results have been achieved with processing ceramic materials. A comprehensive overview of the process and the features is given supported by experimental evidence. Routes of further development are indicated.

null

['Hoopes, Zachary A.', 'Karschner, Michael L.', 'Kelly, Jocelynn', 'Miney, William B.', 'Ounaies, Zoubeida', 'Basak, Amrita']

2021-12-06T21:18:45Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90674', 'http://dx.doi.org/10.26153/tsw/17593']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['direct ink writing', 'DIW', 'biopolymer', 'ethyl cellulose', 'printability']

Printability Assessment of Cellulose-Based Polymer Structures using Direct Ink Writing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9e1135df-5709-4c33-b36d-5f45857e0ae8/download

University of Texas at Austin

In this paper, we demonstrate the preparation and printing of ethyl cellulose, a cellulose derivative, using a custom-modified direct ink writing (DIW) printer. Ethyl cellulose (EC) is widely used as a thin-film coating in controlled-release vitamins and medical pills as well as a thickener in the food, cosmetics, and other industries. It is, therefore, an attractive bio-mass derived polymer for 3D printing. Two types of ethyl cellulose, with different molecular weights (Mw), are dissolved in alpha-terpinol solvent to assess the feasibility of printing the polymer. In total, eleven different slurries are prepared at different solid weight percent. The stir time, stir temperature, and resting time are then varied. The results show that 10 wt. % ethyl cellulose slurry performs best for the initial printability assessment. Following printing, this slurry holds its shape, and shows uniform thickness in rectangular and snake patterns.

null

['Jones, J.B.', 'Wimpenny, D.I.', 'Chudasama, R.', 'Gibbons, G.J.']

2021-10-05T14:45:35Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88384', 'http://dx.doi.org/10.26153/tsw/15323']

ita

2011 International Solid Freeform Fabrication Symposium

Open

['laser printing', 'selective deposition', 'fiber laser consolidation', 'selective processing', 'printed circuit boards']

Printed Circuit Boards By Selective Deposition and Processing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/705d5fc4-8119-44a7-a0b5-fd057eee0149/download

University of Texas at Austin

With electronic applications on the horizon for AM, comes the dilemma of how to consolidate conductors, semi-conductors, and insulators in close proximity. To answer this challenge, laser printing (selective deposition) was used in tandem with fiber laser consolidation (selective processing) to produce PCBs for the first time. This combination offers the potential to generate tracks with high mechanical integrity and excellent electrical conductivity (close to bulk metal) without prolonged exposure of the substrate to elevated temperatures. Herein are the findings of a two-year feasibility study for a “one-stop” solution for producing PCBs (including conductive tracks, dielectric layers, protective resists, and legends).

null

['Foster, Diana', 'Corey, Chris', 'Fisher, Chris', 'Smith, Caitlin', 'Paolella, Arthur']

2021-11-30T20:54:18Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90544', 'http://dx.doi.org/10.26153/tsw/17463']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['quasi-optical', 'millimeter', 'wave guide', 'lens systems', 'radio frequency', 'CLIP', 'PolyJet', 'SLS', 'radar', 'space', 'communications']

Printed Materials and Their Effects on Quasi-Optical Millimeter Wave Guide Lens Systems

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5339d167-2e7e-4835-96c3-ebd21edb3417/download

University of Texas at Austin

This study of 3D printed quasi-optical (Q-O) millimeter wave guide lens systems is presented in three phases: the characterization of 3D printed materials for radio frequency (RF) applications and systems; the development and demonstration of 3D printing technology for RF systems; and the design process, simulation, fabrication, and testing of RF lens systems. The first phase explores the ability to print high-quality materials with fine resolution and the determination of each material’s dielectric constant and loss tangent. The second phase details the development of dual biconvex shaped lens systems and the resulting test data. The third phase combines the former stages’ results to model, print, and test a set of lenses pre-aligned with an integrated support structure. These lens systems were tested up to 100 GHz with demonstrated focusing gain of 22.1 dB.

null

['Periard, Daniel', 'Malone, Evan', 'Lipson, Hod']

2020-03-10T16:02:16Z

9/5/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80218', 'http://dx.doi.org/10.26153/tsw/7237']

eng

2007 International Solid Freeform Fabrication Symposium

Open

freeform fabrication

Printing Embedded Circuits

Conference paper

https://repositories.lib.utexas.edu//bitstreams/73f38f5c-1fd6-4ee4-8332-2c447d223337/download

null

Automated manufacturing technologies such as freeform fabrication can greatly reduce the cost and complexity of infrastructure required to manufacture unique devices or invent new technologies. Multi-material freeform fabrication processes under development have the potential to automatically build complete functional devices including electronics. Making this technology available to creative individuals will revolutionize art and invention, but requires extensive simplification and cost reduction of what is still a laboratory technology. The combination of a Fab@Home Model 1 personal fabrication system and commercially available materials allows the demonstration of simple and inexpensive freeform fabrication of functional embedded electrical circuits, and useful devices. Using this approach, we have been able to demonstrate an LED flashlight, functional printed circuit boards in 2-dimensions and 3- dimensions that are actually entirely printed, and a child’s toy with embedded circuitry. These results, and the materials and methods involved in producing them will be presented in detail.

null

['Periard, Dan', 'Schaal, Noy', 'Schaal, Maor', 'Malone, Evan', 'Lipson, Hod']

2020-03-10T16:20:10Z

8/21/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80223', 'http://dx.doi.org/10.26153/tsw/7242']

eng

2007 International Solid Freeform Fabrication Symposium

Open

freeform fabrication

Printing Food

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b8502579-6a20-43a5-a4f6-9272b600bd45/download

null

This paper examines the possible applications of food as a raw material in freeform fabrication, and provides several demonstrations of edible three-dimensional objects. The use of edible materials offers several advantages: First, it opens the door to the application of SFF technology in custom food industry, such as manufacturing of complex confections with specialized geometries and intricate material compositions. For pedagogical purposes, edible materials provide an easily accessible, nontoxic and low cost way to experiment with rapid prototyping techniques using educational systems such as Fab@Home. For more traditional SFF technologies, food materials with appropriate rheological properties can serve as sacrificial, bio-degradable, bio-compatible or recyclable materials for structural support and draft-printing. We have used the Fab@Home personal fabrication system to produce multi-material edible 3D objects with cake frosting, chocolate, processed cheese, and peanut butter. These are just indicative of the range of potential edible materials and applications.

null

['Rosen, David W.', 'Margolin, Lauren', 'Vohra, Sanjay']

2020-03-11T15:19:56Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80249', 'http://dx.doi.org/10.26153/tsw/7268']

eng

2008 International Solid Freeform Fabrication Symposium

Open

ultrasonic actuation

Printing High Viscosity Fluids using Ultrasonic Droplet Generation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/25f51b61-7710-4f3a-89fa-de5a9a549d94/download

null

A new printing technology based on ultrasonic actuation (~1 MHz) is presented that has the potential to print high viscosity fluids. In this paper, we describe the print-head’s operating principles and construction. Acoustic focusing in the nozzles produces high pressure gradients that help eject the fluid which, under the proper conditions, forms droplets. Two types of models are presented to attempt to predict print-head behavior over a range of conditions. The first model borrows from simple fully developed, laminar flows to estimate printing conditions based on fluid properties, as well as printing pressures. The second model captures the dynamic behavior of the print-head to estimate cavity resonances that lead to acoustic focusing and potentially droplet generation. We report on experiments with several types of fluids that demonstrate the technology’s potential.

null

["O'Donnell, M.", 'Budan, J.', 'McGuire, J.', 'Jalagam, P.', 'Kulkarni, Achyuth', 'Ansell, T.Y.']

2024-03-25T22:39:12Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124326', 'https://doi.org/10.26153/tsw/50934']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['hydrophobic surfaces', 'stainless steel', 'graphene', 'additive manufacturing']

PRINTING HYDROPHOBIC STAINLESS STEEL GRAPHENE COMPOSITES

Conference paper

https://repositories.lib.utexas.edu//bitstreams/02a70354-1db8-4c06-a1c9-8a086235ed79/download

University of Texas at Austin

Hydrophobic surfaces have low surface energies, which prevents water droplets from wetting the surface. Metals typically have high surface energies leading to highly wettable, hydrophilic behavior. Nano-structuring metallic surfaces could be a way of making a metallic surface hydrophobic potentially leading to improved corrosion resistance, drag reduction, etc. 3Dprinting a metal matrix nanocomposite maybe a scalable method to fabricate hydrophobic metals. Graphene nanoplatelets (GNP) were mixed with 316L stainless-steel (SS) powder and printed on a selective laser melting platform. The composite samples included 0, 1, 2, and 3 vol% GNP. Initial printing jobs ran into some issues that were addressed by adding a vibration source and aluminum foil to the inside of the powder hopper. Additionally, energy density was set higher than 60 J/mm3 to avoid lack of fusion issues. Printing of small and large plates of composite samples was performed at energy densities starting from 60 J/mm3 going up to 100 J/mm3 . As-printed composite sample surfaces consistently exhibited hydrophobic behavior with contact angles exceeding 90°. After polishing, the surfaces exhibited hydrophilic behavior. What is compelling; however, is that while contact angles for pure SS was as expected, i.e., angles < 80°, the composite samples showed angles between 80° and 90°, drawing closer to 90° with an increase in GNP.

null

['Granizo, Juan', 'Gribbins, Cassandra', 'Steinhauer, Heidi']

2021-11-08T23:35:23Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90078', 'http://dx.doi.org/10.26153/tsw/16999']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['printing orientation', 'implicit', 'additive manufacturing', 'middle school students', 'high school students']

Printing Orientation and How Implicit It Is

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dc8c844c-8ba2-4ec6-ae67-4dfe538764ea/download

University of Texas at Austin

A study on how implicit the printing orientation is for people with no previous experience in additive manufacturing was conducted. The study was developed with middle and high school students divided into two groups, where only one group was introduced a series of activities to show the importance of printing orientation and its relation with stress and strength of parts. Both of the groups were evaluated in the construction of a wing-box using 3-D printing pens. The study also took into consideration the amount of filament that was used in the assembly of the structure, to keep track of the most optimized models. The wing-box were then tested until failure to study its structural integrity. Finally, a detailed comparison between the two studied groups was perform to show how implicit the printing orientation is in the design process of parts.

null

['Norris, Marshall', 'Fidan, Ismail']

2024-03-26T21:39:10Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124423', 'https://doi.org/10.26153/tsw/51031']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'metallic paste', '17-4PH', 'parameter optimization', 'response surface']

PRINTING PARAMETER OPTIMIZATION OF EXTRUDED METAL PASTE BY RESPONSE SURFACE TECHNIQUE

Conference paper

https://repositories.lib.utexas.edu//bitstreams/306d6744-b5d5-41c4-b698-c17367e6ec92/download

University of Texas at Austin

This research is focused on optimizing printing parameters using the response surface (RS) methodology. When printing parameters are not optimized, the resulting prints contain an unacceptable surface finish, porosity, or the print fails entirely as the lower portion of the print will not be able to withstand the weight of consecutive layers. Printing parameters, layer height, and percent infill were adjusted for the study while material flow rate and print head speed were held constant. RS is a statistical based eigenvalue process that uses data points on a three-dimensional curve to predict and identify local maxima or minima. For this study, RS was used to identify the inflection point where surface finish is optimized. A starting point for the parameters begins with rheological characterization of the paste and geometric modeling (or brute force approach). Once the parameters are able to produce an acceptable surface finish, the RS approach was used to refine printing parameters.

null

['Zhang, Jingwei', 'Liou, Frank', 'Seufzer, William', 'Newkirk, Joseph', 'Fan, Zhiqiang', 'Liu, Heng', 'Sparks, Todd E.']

2021-10-11T22:26:10Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88668', 'http://dx.doi.org/10.26153/tsw/15602']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['microstructure evolution', 'metal solidification', 'laser based additive manufacturing', 'Cellular Automaton - Finite Element', 'metal deposition']

Probabilistic Simulation of Solidification Microstructure Evolution During Laser-Based Metal Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c9f27299-6b7e-447f-af4c-c943da56c078/download

University of Texas at Austin

A predictive model, based on a Cellular Automaton (CA) - Finite Element (FE) method, has been developed to simulate microstructure evolution during metal solidification for a laser based additive manufacturing process. The macroscopic FE calculation was designed to update the temperature field and simulate a high cooling rate. In the microscopic CA model, heterogeneous nucleation sites, preferential growth orientation and dendritic grain growth kinetics were simulated. The CA model was able to show the entrapment of neighboring cells and the relationship between undercooling and the grain growth rate. The model predicted the dendritic grain size, structure, and morphological evolution during the solidification phase of the deposition process. Model parameters for the simulations were based on stainless steel 316 (SS 316).

null

['Lak, Sui Man', 'Li, Chi Chung', 'Toombs, Joseph', 'de Beer, Martin', 'Taylor, Hayden']

2024-03-26T21:42:53Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124424', 'https://doi.org/10.26153/tsw/51032']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['tomographic fuorescence imaging', 'temperature', 'degree-of-conversion', 'additive manufacturing']

Probing Temperature and Degree-of-conversion States via Tomographic Fluorescence Imaging

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2b9a0def-165e-4b2d-be6e-5356bf178411/download

University of Texas at Austin

Tomographic volumetric additive manufacturing rapidly solidifies freeform objects via photopolymerization, which raises both local temperature and degree-of-conversion (DOC). Insitu monitoring of temperature and DOC during the printing process is crucial for metrology and process control. In this study, we propose a tomographic fluorescence imaging technique to detect the spatiotemporal evolution of temperature and DOC during volumetric printing. Our solution employs a fluorescent dye that is sensitive to both variations in temperature and DOC. DOC is considered as a function of, and is expressed in, the absorbed optical dose of the resin. By tomographically measuring changes in the dye’s fluorescence intensity and feeding such changes to a temperature–dose–intensity calibration, the local dose and temperature during the print can be confined to a set of possible states. At exemplar locations where a priori information is known for one quantity, the other quantity can be resolved. This work illustrates the potential of and lays foundations for the development of two-wavelength spatiotemporal measurement systems that uniquely resolve both temperature and DOC.

null

['De Coninck, H.', 'Dejans, A.', 'Meyers, S.', 'Buls, S.', 'Kinds, Y.', 'Soete, J.', 'Van Puyvelde, P.', 'Van Hooreweder, B.']

2024-03-25T22:51:58Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124328', 'https://doi.org/10.26153/tsw/50936']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['Polyamide 12', 'glass fibres', 'fibre/matrix behaviour', 'glass fibre sizing', 'laser sintering', 'deposition system', 'additive manufacturing']

PROCESS AND MATERIAL OPTIMISATIONS FOR INTEGRATION OF CHOPPED GLASS FIBRES IN LASER SINTERED POLYMER PARTS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2e85d4d9-2634-4f37-8779-a9b2db3286e4/download

University of Texas at Austin

Additively manufactured polymer composites gain popularity in a variety of industries such as aerospace, biomedical and automotive. Laser sintering (LS) is a well-known AM process that typically uses polyamide which can serve as matrix material. Hence LS has the potential to produce reinforced polymers that can meet demanding requirements. In previous research, issues with powder flowability and poor fibre dispersion led to limited increase of mechanical properties. To overcome this, a novel fibre deposition system was recently developed and optimised at KU Leuven to successfully produce fibre reinforced LS samples with random inter- and intralayer fibre orientations. A limited but promising influence of deposited glass fibres on produced LS parts was noted after mechanical testing. In this work, the influence of different (heat) treatments on glass fibres used during LS will be discussed as well as the resulting differences in the fibre/matrix behaviour as analysed through hot stage microscopy.

null

['Artreya, S.', 'Kalaitzidou, K.', 'Das, S.']

2021-09-29T14:57:24Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88189', 'http://dx.doi.org/10.26153/tsw/15130']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['electrically conductive polymer composites', 'Selective Laser Sintering', 'Nylon-12', 'electrical conductivity']

Process and Properties of Carbon Black-Filled Electrically Conductive Nylon-12 Nanocomposites Produced by Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ff634746-d7fe-49eb-88ca-a986c63a1da0/download

University of Texas at Austin

Electrically conductive polymer composites are suitable for use in the manufacture of antistatic products and components for electronic interconnects fuel cells and electromagnetic shielding. Selective laser sintering (SLS) was used to investigate the fabrication of electrically conductive nanocomposites of Nylon-12 filled with 4% by weight of carbon black. The effect of laser power and the scan speed on the flexural modulus and part density of the nanocomposite were studied. The set of parameters that yielded the maximum flexural modulus and part density was used to fabricate specimens to study the tensile, impact, rheological and viscoelastic properties. The electrical conductivity of the nanocomposite was investigated. The densities and the microstructures of the nanocomposites were studied using optical microscopy and scanning electron microscopy (SEM). The morphology of the nanocomposites was investigated using X-Ray diffraction (XRD) and differential scanning calorimetry.

null

['Branner, G.', 'Strasser, G.', 'Zaeh, M.F.']

2020-03-09T14:50:59Z

9/5/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80189', 'http://dx.doi.org/10.26153/tsw/7208']

eng

2007 International Solid Freeform Fabrication Symposium

Open

indirect metal laser sintering

Process Chain for Numerical Simulation of IMLS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/411bab75-ccde-4443-b6a1-c30772755415/download

null

Additive layer manufacturing methods imply, among other advantages, extensive flexibility concerning their ability to realize mass customization. Despite various efforts towards process enhancement, numerous deficiencies concerning part distortion or residual stresses are still observable. The present work deals with the definition of an efficient process chain for numerical simulation of indirect metal laser sintering (IMLS), in order to improve dimensional accuracy. The underlying method is based on investigations of dilatometric behavior of iron based powder, which is integrated into reaction kinetic models and coupled with a finite element analysis (FEA). Thus, singular process steps, e. g. solid phase sintering, phase transformations or infiltration, are numerically modelled with adequate accuracy. Referring to thermomechanical simulation, possibilities for pre-scaling of part geometries are presented.

null

['Kovacevic, R.', 'Beardsley, H.']

2019-02-19T16:51:33Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73429', 'http://dx.doi.org/10.26153/tsw/581']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['rapid prototyping', 'stereolithography']

Process Control of 3D Welding as a Droplet-Based Rapid Prototyping Technique

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f9ed1f6e-a110-4a69-8e02-122c9f652a41/download

null

Three-dimensional welding is investigated as a rapid prototyping technique for the production of real Inetallic parts using gas metal arc welding principles. A high speed machine vision system is used to study the correlation between droplet transfer parameters and resultant weld penetration characteristics. Experimental work is conducted to determine how droplet transfer frequency, droplet size, and number of passes affect the geometrical and Inetallurgical properties ofthe weld penetration. A finite element analysis is performed in order to study what influence additional layering has on the cooling characteristics and resultant penetration profile.

null

Landers, Robert G.

2019-11-20T16:32:28Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78475', 'http://dx.doi.org/10.26153/tsw/5560']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Laser Metal

Process Control of Laser Metal Deposition Manufacturing - A Simulation Study

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b7b6fadc-4c5f-4af7-a5d0-a0190986a26b/download

null

The laser metal deposition process is a rapid manufacturing operation capable of producing functional prototypes with complex geometries and thin sections. This process inherently contains significant uncertainties and, therefore, extensive experimentation must be performed to determine suitable process parameters. An alternative is to directly control the process on–line using feedback control methodologies. In this paper, a nonlinear control strategy based on feedback linearization is created to automatically regulate the bead morphology and melt pool temperature. Extensive simulation studies are conducted to validate the control strategy.

The author gratefully acknowledges the financial support of the National Science Foundation (DMI–9871185), Society of Manufacturing Engineers (#02022–A), Missouri Research Board, and UMR’s Intelligent Systems Center.

null

['Das, Suman', 'Crawford, Richard H.', 'Beaman, J.J.']

2018-04-18T17:35:58Z

1992

Mechanical Engineering

doi:10.15781/T2SF2MV5H

http://hdl.handle.net/2152/64364

eng

1992 International Solid Freeform Fabrication Symposium

Open

['Department of Mechanical Engineering', 'High Temperature Workstation', 'HTW']

Process Control System for a High Temperature Workstation performing the Selective Laser Sintering Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1b464dec-275e-4400-8c92-da06e0b64f4f/download

null

Thispaper describes the design and implementation ofa Computer Process Control System for a High Temperature Workstation performing Selective Laser Sintering of metal and .ceramic powders. As compared to our previous machine [1], the increased complexity and sophistication .of·the.new workstation [21 requires a variety of measurement and control devices which are.interfaced to a process controlcomputer. Among these are a. gas analyzer, a data logger, a step motor controllerandaCNC controller. This process control system incorporates a XView ( aX Window System Toolkit) based Graphical User Interface which allows the user.to set and change process parameters on-line as well as receive graphical feedback onthe process.

null

Tille, Carsten

2020-02-13T19:51:58Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79970', 'http://dx.doi.org/10.26153/tsw/6995']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Stereolithography

Process Errors and Aspects for Higher Resolution in Conventional Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dcc10f81-2bed-40bb-a78f-070ea4a5030f/download

null

Due to the rapid development of precision manufacturing technologies, there is a growing market need for appropriate rapid prototyping methods with higher resolution. This paper presents aspects for a general optimization of stereolithography accuracy and gives a deeper analysis of important process errors. Beside a higher precision due to improved optical components, it can be shown that for a better vertical resolution one must mainly reduce the penetration depth of the photopolymer. We found that this is also possible with conventional stereolithography materials by using a different wavelength, achieving cured rugged layers with a thickness of 20 micrometer. The major accuracy aspect lies in the understanding of the layer deposition process. A CFD (computational fluid dynamics) study helps to describe important phenomena of blade based coating techniques. As a result, the inaccuracy of the layer deposition is the general limiting factor in stereolithography. This knowledge can be directly applied to commercial stereolithography systems helping users to achieve higher process accuracy.

null

Chi, Chen

2018-11-16T14:57:33Z

1996

Mechanical Engineering

doi:10.15781/T2KP7VB2P

http://hdl.handle.net/2152/70284

eng

1996 International Solid Freeform Fabrication Symposium

Open

['LOM', 'rapid prototyping', '3-dimensional objects']

Process Insight About LOM Systems

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1567cc04-f0ca-4b9c-a8d5-7ae979d154a6/download

null

A Laminated Object Manufacturing (LOM) machine offers much freedom in terms ofsystem parameters: laser cutting speed, laser power setting, roller speed, roller temperature, and so on. Because ofthis freedom, users can choose any number, within certain limitations, to create wellconstructed objects. Obviously, each user has a different definition for the quality of an object. Therefore this freedom has induced some confusion. Most commonly, each customer has his own preferred parameter data sets. These sets may not be the same but they are good sets. We need to devise a method as a guideline for system parameters to ensure a consistency in the construction of objects. We have been studying actual laser power at different cutting speeds, actual cutting curves and bonding curves for different materials, actual temperature distribution, etc. These results have helped us find a proper way to set system parameters so that any user can run LOM machines without difficulty and confusion. The research methodology and results are elaborated in this paper.

null

['Lehmann, Maja', 'Zaeh, Michael F.']

2021-11-16T15:57:27Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90323', 'http://dx.doi.org/10.26153/tsw/17244']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['cobalt gradient', 'WC-Co', 'sintering', 'binder jetting', 'nanoparticles']

Process Integrated Production of WC-Co Tools with Local Cobalt Gradient Fabricated by Binder Jetting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/decc78aa-9a02-4f5f-9178-ed9a8965e7ce/download

University of Texas at Austin

Producing complex shaped tungsten carbide cobalt (WC-Co) tools by classical technologies is difficult and often impossible due to their high hardness and brittle fracture behavior. Additive Manufacturing (AM) is a suitable technology for creating complex structures and simultaneously shortening expensive machining processes. Binder Jetting (BJ) is an innovative AM technology that offers several advantages over laser-based processes, for example low manufacturing costs and high build-up rates. Binders with nanoparticle additives have already proven to be effective in increasing the packing density of the powder bed and improving the sintering properties. Additionally, they offer the possibility of selectively changing the material composition in the part. This paper presents a concept for the use of nanoparticles to generate gradients in the green compact, which leads to a cobalt gradient in the part after sintering. The possibility of introducing particles locally into complex structures allows local modification of the material properties.

null

['Cooke, A.L.', 'Moylan, S.P.']

2021-10-04T20:30:55Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88340', 'http://dx.doi.org/10.26153/tsw/15279']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['process intermittent measurements', 'additive manufacturing', 'three-dimensional printing']

Process Intermittent Measurement for Powder-Bed Based Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3bc4c474-d37a-4c0a-9036-37651f7f6f26/download

University of Texas at Austin

Process intermittent measurements of parts fabricated by additive manufacturing (AM) can enable both process improvement and characterization of internal part geometries. The planar, layer-upon-layer nature of most AM processes allows two-dimensional geometric measurements with a vision system, because the part’s current layer is continually in focus. Proof of this concept has been shown through measurement of parts made using a three-dimensional (3D) printer. Process intermittent measurements were compared to contact and non-contact measurements of the finished parts to characterize deviations in printed layer positions and changes in part dimensions resulting from post-process treatments.

null

['Beuth, Jack', 'Fox, Jason', 'Gockel, Joy', 'Montgomery, Colt', 'Yang, Rui', 'Qiao, Haipeng', 'Soylemez, Emrecan', 'Reeseewatt, Pete', 'Anvari, Amin', 'Narra, Sneha', 'Klingbeil, Nathan']

2021-10-11T21:54:40Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88656', 'http://dx.doi.org/10.26153/tsw/15590']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'process mapping', 'direct metal deposition', 'melt pool geometry', 'microstructure']

Process Mapping for Qualification Across Multiple Direct Metal Additive Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c5b02008-133b-4e40-893d-96f1d557e8c6/download

University of Texas at Austin

This paper gives an overview of work by the authors developing process mapping methods for additive manufacturing (AM), capturing the dependence of melt pool geometry and microstructure on primary processing variables under steady-state and transient conditions. This work is being applied to the task of process qualification and is being applied across multiple AM processes including electron beam wire feed, electron beam powder bed, laser powder bed, and laser powder stream processes. Process mapping methods are now allowing all of these processes acting in very different regions of processing space to be characterized and analyzed in a unified way. A few insights from this approach are summarized.

null

['Montgomery, Colt', 'Beuth, Jack', 'Sheridan, Luke', 'Klingbeil, Nathan']

2021-10-21T17:57:06Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89411

eng

2015 International Solid Freeform Fabrication Symposium

Open

['laser powder bed additive manufacturing', 'nickel superalloys', 'Inconel 625', 'process mapping']

Process Mapping of Inconel 625 in Laser Powder Bed Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f4262fbd-f005-4f4d-800e-b3cc5bab848f/download

University of Texas at Austin

Understanding laser powder bed additive manufacturing of nickel superalloys is important for the widespread adoption of the technology. To promote adoption, melt pool geometry as well as microstructure prediction and control must be thoroughly understood. In this research Inconel 625 is investigated to determine optimal regions of processing space within the laser powder bed operating range. Single bead and pad geometries are investigated along with solidification microstructure and defects by utilizing a process mapping approach. The effect of powder addition on the process is also examined. Results from models are compared with experimental results to verify modeling techniques. Insights are gathered by comparing these results to those of other alloy systems in the laser powder bed operating space.

null

['Fox, Jason', 'Beuth, Jack']

2021-10-11T22:00:47Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88658', 'http://dx.doi.org/10.26153/tsw/15592']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['wire feed electron beam additive manufacturing', 'additive manufacturing', 'process mapping', 'Ti-6Al-4V', '3D finite element simulation', 'aerospace']

Process Mapping of Transient Melt Pool Response in Wire Feed E-Beam Additive Manufacturing of Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2cb071b2-260f-409d-92c4-83a324cd55f2/download

University of Texas at Austin

Wire feed electron beam additive manufacturing processes are candidates for manufacturing and repair in the aerospace industry. In order to implement feedback or feedforward control approaches, the time needed for a change in process variables to translate into changes in melt pool dimensions is a critical concern. In this research, results from 3D finite element simulations of deposition of Ti-6Al-4V are presented quantifying the transient response of melt pool dimensions to rapid changes in beam power and travel velocity. Results are plotted in beam power vs. beam velocity space, following work by the authors developing P-V Process Maps for steady-state melt pool geometry. Transient responses are determined over a wide range of process variables. Simulation results are compared to initial results from experiments performed at NASA Langley Research Center.

null

['Vasinonta, Aditad', 'Beuth, Jack', 'Griffith, Michelle']

2019-09-23T15:37:40Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75939', 'http://dx.doi.org/10.26153/tsw/3038']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Residual

Process Maps for Controlling Residual Stress and Melt Pool Size in Laser-Based SFF Processes 200

Conference paper

https://repositories.lib.utexas.edu//bitstreams/aefec396-2f89-499f-b0ab-1b0dcb30124f/download

null

Thermal control of solid freeform fabrication processes is critical for obtaining consistent build conditions and in limiting residual stress-induced tolerance losses. In this paper, thermomechanical models are presented for the building of thin-walled structures by laser-based SFF processes. The simulations are used to develop two non-dimensional plots (termed process maps) that quantify the effects of changes in wall height, laser power, deposition speed and part preheating on melt pool size (for consistent build conditions) and thermal gradients (for limiting residual stresses). Mechanical simulations are used to demonstrate the link between thermal gradients and maximum final residual stresses. Models are applied to the Laser Engineered Net Shaping (LENS) process; however, the general approach, insights and conclusions are applicable to most SFF processes involving a moving heat source. The two process maps described herein can be used together to determine optimal process variables for obtaining consistent melt pool length while limiting residual stress in the part. Results from the residual stress simulations also identify two important mechanisms for reducing residual stresses and quantify maximum stress reductions that can be achieved through manipulation of all process variables.

This research has been supported by the National Science Foundation under grant DMI9700320 and by Sandia National Laboratories under grant BE-0792.

null

['Vasinonta, Aditad', 'Beuth, Jack', 'Griffith, Michelle']

2019-03-17T13:35:45Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73697', 'http://dx.doi.org/10.26153/tsw/839']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['LENS', 'SFF']

Process Maps for Laser Deposition of Thin-Walled Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5cec0fd7-2ad3-431a-9573-c406fb46342c/download

null

In solid freeform fabrication (SFF) processes involving thermal deposition, thermal control of the process is critical for obtaining consistent deposition conditions and in limiting residual stress-induced warping of parts. In this research, nondimensionalized plots (termed process maps) are developedJrom numerical models of laser-based material deposition of thin-walled structures that.map out the effects of changes in laser power, deposition speed and part preheating on process parameters. The principal application of this work is to the Laser Engineered Net Shaping (LENS) process under development at Sandia Laboratories; however, the approach taken is applicable to any solid freeform fabrication process involving. a moving heat source. Similarly, although thinwalled structures treated in the current work, the same approach could be applied to other commonly fabricated geometries. A process map for predicting and controlling melt pool size is presented .and numerically determined results are compared against experimentally measured melt poollengthsfor stainless steel deposition in the LENS process.

null

['Wang, J.', 'Zhao, C.', 'Zhang, Y.', 'Jariwala, A.', 'Rosen, D.']

2021-11-04T14:56:55Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89977

eng

2017 International Solid Freeform Fabrication Symposium

Open

['exposure controlled projection lithography', 'ECPL', 'photopolymerization', 'process modeling', 'in-situ monitoring', 'real-time']

Process Modeling and In-Situ Monitoring of Photopolymerization for Exposure Controlled Projection Lithography (ECPL)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/95c33e40-fd1f-45ad-9ed2-6fc600328633/download

University of Texas at Austin

Exposure controlled projection lithography (ECPL) is an additive manufacturing process in which photopolymer resin is used to fabricate three-dimensional features. During this process, UV curing radiation, controlled by a dynamic mask, is projected through a transparent substrate onto the resin. COMSOL software has been used to model the photopolymerization reaction kinetics, predicting the cured part geometry based on certain process parameters. Additionally, an Interferometric Curing Monitoring (ICM) system has been implemented to acquire real-time information about the optical properties of the cured part. Potential sources of error with the real-time monitoring system were investigated. Additionally, refractive index and degree of conversion changes were modeled throughout the reaction. Measured and simulated results were compared to understand the ICM signal with the reaction kinetics. These comparisons were used to validate the simulation model and identify system level errors that must be reconciled to improve the accuracy and precision of the ECPL process.

null

['Appana, S.', 'Ross, S.M.', 'Sims, C.', 'Schwerzel, R.', 'Jariwala, A.S.']

2024-03-26T21:47:10Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124425', 'https://doi.org/10.26153/tsw/51033']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['fuild interface supported printing', 'stereolithography', 'resin', 'additive manufacturing']

PROCESS MODELING FOR FLUID-INTERFACE SUPPORTED RESIN PRINTING

Conference paper

https://repositories.lib.utexas.edu//bitstreams/eb9a68d2-a9fd-4748-bd28-505427e9910f/download

University of Texas at Austin

The article details the latest design and implementation of a stereolithography (SLA) based technique, Fluid Interface Supported Printing (FISP). The FISP technique involves printing from a thin resin layer above a static, immiscible support fluid. The support fluid prevents deflection of overhanging geometry by providing a buoyant force equal to that of the gravitational force due to the minute density difference between the support fluid and cured resin. Complex curing and shrinkage dynamics are a primary knowledge gap. A COMSOL multiphysics simulation model was developed to simulate the curing process, including volumetric light intensity and optimized parameters for chemical reaction kinetics. The article presents a pathway for further enhancing and validating the simulation model.

null

['Griffis, J.C.', 'Shahed, K.S.', 'Okwudire, C.E.', 'Manogharan, G.P.']

2024-03-26T20:14:16Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124390', 'https://doi.org/10.26153/tsw/50998']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'process modeling', 'additive manufacturing']

PROCESS MODELING OF MULTI-MATERIAL LASER POWDER BED FUSION

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1a8b2f6a-b0cc-4385-8415-e7d99f1656f4/download

University of Texas at Austin

Thermomechanical simulation of the laser powder bed fusion process has been a valuable tool to help researchers and practitioners across the AM production cycle. For instance: Design for AM (DfAM), material development, process mapping, prediction, and support generations, among others. In this study, multi-material laser powder bed fusion (MM-LPBF), specifically of 904LSS and CuSn10 are examined through process simulation and non-destructive techniques to determine the impact of component orientation on defect mitigation. It is determined that material orientation along the build direction is a large contributor in as-build defects. Introductory MM-LPBF simulation is established to better understand the capabilities of current LPBF simulation tools in accurately predicting and mitigating the new challenges of MM-LPBF simulation.

null

['Munjuluri, N.', 'Agarwal, S.', 'Liou, F.W.']

2019-09-23T15:47:20Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75943', 'http://dx.doi.org/10.26153/tsw/3042']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Modeling

Process Modeling, Monitoring and Control of Laser Metal Forming 235

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f633aec5-ea6b-43d3-b042-0b126494f346/download

null

Laser Metal Forming (LMF) process is one of the prominent Rapid Prototyping (RP) process that can be used to develop functional and fully dense metal parts. This paper addresses process modeling, monitoring and control of a laser metal forming system currently under development at Laser Aided Manufacturing Processes (LAMP) laboratory at University of Missouri–Rolla. This LMF system is based on a 2.5kW Nd:YAG laser as energy source and integrates five axis metal deposition and five axis machining. The current paper is aimed at characterization of effects of operating parameters such as traverse speed, mass flow-rate and laser power on the LMF process. A low cost monitoring system is being developed using off the shelf sensors like infrared temperature sensor, near infrared CCD camera and laser displacement sensor to measure the process index parameters. A closed loop control structure has been simulated for online control of the LMF process.

This research was supported by the National Science Foundation Grant Number DMI-9871185, Missouri Research Board, and a grant from the Missouri Department of Economic Development through the MRTC grant

null

['Wegner, A.', 'Witt, G.']

2021-10-04T22:14:17Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88364', 'http://dx.doi.org/10.26153/tsw/15303']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'process monitoring', 'thermal imaging']

Process Monitoring in Laser Sintering Using Thermal Imaging

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6200bf44-1010-4093-bf7b-5a7249a82191/download

University of Texas at Austin

In laser sintering, inhomogeneous shrinkage, warpage, in-build curling and poor repeatability of part properties are well-known problems. All these effects are significantly influenced by the inhomogeneous temperature distribution on the powder bed surface. For this reason, it is often asked for the integration of additional measuring equipment into the machines for advanced process monitoring. In the research done, a thermal imaging system was successfully integrated into a laser sintering machine. Analyses were performed to understand the correlations between process parameters, the distribution of surface temperatures as well as the temperature of the melted material, and their influence on part properties.

null

['Nassar, A.R.', 'Starr, Brandon', 'Reutzel, E.W.']

2021-10-19T19:13:34Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89327

eng

2014 International Solid Freeform Fabrication Symposium

Open

['spectroscopy-based imaging', 'spectroscopy', 'directed energy deposition', 'Inconel-718', 'plume geometry']

Process Monitoring of Directed-Energy Deposition of Inconel-718 via Plume Imaging

Conference paper

https://repositories.lib.utexas.edu//bitstreams/be9b3423-8b66-408b-bdd9-9cae29c54578/download

University of Texas at Austin

Laser-metal interactions typically results in vaporization and plume formation. These phenomena are complex and depend upon the details of the laser-vapor-melt interactions. As such, plume characteristics are sensitive to changes in process characteristics. Here, a spectroscopy-based imaging technique is presented for the monitoring of directed energy deposition of Inconel 718. Plume geometry is shown to be related to the processing parameters and geometry of single-bead deposits.

null

['Leslie Budden, Christian', 'Lalwani, Aakil Raj', 'Meinert, Kenneth Ælkær', 'Daugaard, Anders Egede', 'Pedersen, David Bue']

2023-01-19T20:20:13Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117252', 'http://dx.doi.org/10.26153/tsw/44133']

eng

2022 International Solid Freeform Fabrication Symposium

Open

PA11

Process optimisation of PA11 in fiber-laser powder-bed fusion through loading of an optical absorber

Conference paper

https://repositories.lib.utexas.edu//bitstreams/28001ace-6d24-4270-884c-9ae6cd97e992/download

null

Industrial laser processing is rapidly shifting towards fiber lasers with wavelengths between 780nm and 2200nm. This can be largely contributed to the excellent beam properties and, ease of operation. However, for Additive Manufacturing of polymers, CO2 lasers at wavelengths of 10,6µm are pre- dominantly used. CO2 lasers provide unmatched energy absorption by the C-H bonds of Polyamide (PA). To remedy this, the current study investigates using a high-power fiber laser (1080nm) for consolidating PA11 mixed with a black optical absorber. Several compositions are produced by mixing commercially available white and black powder. Aiming at finding the optimum optical absorber loading and the corresponding process parameters, allowing the highest possible compo- nent fidelity, while achieving the lightest hue of grey possible to allow for later colouring. The experiment is conducted on an in-house developed Open Architecture Laser Powder-Bed Fusion system. The parts are examined through, surface roughness, and mechanical characterisation.

null

['Kempen, K.', 'Thijs, L.', 'Yasa, E.', 'Badrossamay, M.', 'Verheecke, W.', 'Kruth, J.-P.']

2021-10-05T13:47:43Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88371', 'http://dx.doi.org/10.26153/tsw/15310']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['AlSi10Mg', 'Selective Laser Melting', 'process optimization', 'microstructural analysis', 'heat sinks']

Process Optimization and Microstructural Analysis for Selective Laser Melting of AlSi10Mg

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bb26039f-60c4-4fe2-9b57-60499f0b387e/download

University of Texas at Austin

AlSi10Mg is a typical casting alloy which is, due to its high strength/density ratio and thermal properties, highly demanded in aerospace and automotive industries [1]. The alloy combination of aluminium, silicon and magnesium results in a significant increase in strength and hardness which might even reach 300 MPa and 100 HBS, respectively, by applying a proper heat treatment [2]. Selective Laser Melting (SLM) of AlSi10Mg, may be interesting to open new application areas such as heat sinks with complicated geometry [3], and therefore is taken under investigation in this study. The process optimization of SLM for this alloy is not straightforward due to high reflectivity and conductivity of the material. In this study, the main goal is to optimize the process parameters, namely scan speed, scan spacing and laser power, to achieve almost full density and good surface quality taking productivity as a key issue. A relative density up to 99% is achieved with an average roughness (Ra) of about 20 µm measured on horizontal top surfaces while the scanning productivity is about 4.4 mm3/s. The reasons spherical and irregular porosity formed are investigated. Moreover, microstructural analysis of the SLM samples is conducted.

null

['Keicher, D.M.', 'Lavin, J.M.', 'Appelhans, L.N.', 'Whetten, S.R.', 'Essien, M.', 'Mani, S.S.', 'Moore, P.B.', 'Cook, A.', 'Acree, N.A.', 'Young, N.P.', 'Russell, M.J.']

2021-10-28T19:23:55Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89674

eng

2016 International Solid Freeform Fabrication Symposium

Open

['process optimization', 'aerosol based printing', 'film properties', 'capacitors']

Process Optimization of Aerosol Based Printing of Polyimide for Capacitor Application

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b95f08ee-e39c-4e5a-91c3-8c3e2b74ecf5/download

University of Texas at Austin

Direct write printing approaches provide the opportunity for additive manufacturing (AM) to impact the electronics industry. This class of technologies provides a path to cost effectively print electronic components in low volume, high mix production. The printed electronics technologies provide an opportunity to explore new materials, new processing approaches and unique component configurations to alter the electronics industry. A new project underway to explore printing of planar, nonplanar and three-dimensional capacitors will be discussed. Aerosol based printing technologies applied to dielectric printing have demonstrated the ability to print small features in three dimensions. This presentation will cover recent research in optimizing process variables both with materials and deposition parameters to obtain desirable film properties. This work will compare the film properties using the additive manufacturing approach to traditional casting. Finally, this presentation will describe an optimized process in detail and the rational for the processes chosen.

null

['Hirsch, A.', 'Hecker, F.', 'Moritzer, E.']

2021-11-18T01:14:26Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90387', 'http://dx.doi.org/10.26153/tsw/17308']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['arburg plastic freeforming', 'APF', 'optimization', 'process parameter', 'mechanical properties']

Process Parameter Optimization to Improve the Mechanical Properties of Arburg Plastic Freeformed Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0e735e75-6caa-4b9a-8494-874b3edd6a83/download

University of Texas at Austin

The Arburg Plastic Freeforming (APF) is an additive manufacturing process that allows three-dimensional, thermoplastic components to be produced in layer by layer. The components are generated by depositing fine, molten plastic droplets. One of the main advantages of the APF process is the open machine control. Thus, the process parameters can be adapted and optimized for the individual applications. The optimization is carried out on the basis of a variation of the process parameters using a statistical design of experiments. Relevant process parameters are the layer thickness, the form factor, the raster and delta angle as well as the overlap between the contour and the filling of a layer. In addition, the nozzle and build chamber temperatures are varied. Using this procedure, the effects of the influencing parameters on the mechanical properties and the interactions between the influencing parameters are analyzed and converted into mathematical models. On the basis of the results and the models, guidelines will be developed to assist the user of APF technology in the systematic process configuration for their own applications. The material used is ABS, one of the most frequently used amorphous thermoplastics in additive manufacturing. The mechanical properties are determined on the basis of tensile tests and the characteristic values tensile strength, elongation at break and Young's modulus. The results should show the performance of the APF technology in regard to the mechanical properties.

null

['Yang, Y.', 'Janaki Ram, G. D.', 'Stucker, B. E.']

2020-03-05T20:21:25Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80157', 'http://dx.doi.org/10.26153/tsw/7178']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Ultrasonic Consolidation

Process Parameters Optimization for Ultrasonically Consolidated Fiber-Reinforced Metal Matrix Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d4fcf669-c792-4f97-8560-a9214573f8af/download

null

As an emerging rapid prototyping technology, Ultrasonic Consolidation (UC) has been used to successfully fabricate metal matrix composites (MMC). The intent of this study is to identify the optimum combination of processing parameters, including oscillation amplitude, welding speed, normal force, operating temperature and fiber orientation, for manufacture of long fiber-reinforced MMCs. The experiments were designed using the Taguchi method, and an L25 orthogonal array was utilized to determine the influences of each parameter. SiC fibers of 0.1mm diameter were successfully embedded into an Al 3003 metal matrix. Two methods were employed to characterize the bonding between the fiber and matrix material: optical/electron microscopy and push-out tests monitored by an acoustic emission (AE) sensor. SEM images and data from push-out tests were analyzed and optimum combinations of parameters were achieved.

null

['Pinilla, J. Miguel', 'Kao, Ju-Hsien', 'Prinz, Fritz B.']

2019-02-20T17:15:42Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73454', 'http://dx.doi.org/10.26153/tsw/606']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['CNC machining', 'surface']

Process Planning and Automation for Additive-Subtractive Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1de24334-da86-41ad-8cd4-55371fa5d822/download

null

New additive-subtractive processes promise to enhance SFF capability from prototyping to true low-volume production. However, to maintain the same degree of process automation as in currently available processes like SLA or SLS, more sophisticated planning and execution systems need to be developed. The system we present in this paper consists of two parts. The first is an off-line planner that decomposes a CAD model into 3D manufacturable volumes called "single-step geometries", arranges these geometries into a graph representation called" adjacency graphs", and automatically generates deposition and machining codes for each single-step geometry. The second is an on-line system that handles asynchronous multi-part building, job-shop scheduling, process control and run-time execution. Communication between these two stages is through a "process description language". The goal of this paper is to present a framework for planning and execution for additive/subtractive processes, outline the issues involved in developing such an environment, and report on the progress made in this direction at the Rapid Prototyping Laboratory of Stanford University.

null

['Deuser, Brad', 'Tang, Lie', 'Geldmeiner, Jeff', 'Landers, Robert G.', 'Leu, Ming C.']

2021-10-05T13:25:43Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88365', 'http://dx.doi.org/10.26153/tsw/15304']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'functionally graded materials', 'process planning', 'control system', 'Freeze-form Extrusion Fabrication']

Process Planning and Control for Functionally Graded Material Fabrication Using Freeze-Form Extrusion Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1cc81895-acf2-4899-a686-244700c7994b/download

University of Texas at Austin

Using multiple materials in additive manufacturing technologies is critical for building parts with functionally gradient geometries. In order to achieve a desired material gradient, an advanced process planning and control system is required. This paper details the development of a process planning method and control system for functionally graded material fabrication using a triple extruder Freeze-form Extrusion Fabrication (FEF) system including motion code generation, extruder dynamic modeling and control, and composition gradient control. The effect that extruding multiple materials from a single orifice via static mixing has on the time delay of the resulting mixture is taken into account for path planning, and this factor is incorporated into integrating motion codes with extrusion commands. The effectiveness of the proposed system is demonstrated by fabricating three-dimensional parts with desired gradient compositions using multiple materials.

null

['West, Aaron', 'Rosen, David W.']

2019-03-08T17:48:52Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73573', 'http://dx.doi.org/10.26153/tsw/715']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['Stereolithography', 'Process Planning']

Process Planning Based on User Preferences

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d5d0d424-03a0-4c1f-aa1c-8e36293e621e/download

null

Typical approaches to adaptive slicing in previous literature have typically used surface finish requirements to control the slicing process. As a result, slice schemes improve the part's surface quality, but do not enable explicit trade-offs between finish and build time. The purpose of this article is to present a process planning method that enables the preferences of the user for surface finish, build time, and accuracy to control how trade-offs are made in a process plan. A multiobjective goal formulation is used by this method to evaluate how well user preferences are met by a process plan. This method consists of three modules, for determining part orientation, for slicing the part, and for determining other parameter values. An example with several scenarios representing different user preferences is provided to illustrate the process planning method.

null

['Dwivedi, Rajeev', 'Kovacevic, Radovan']

2019-11-08T15:23:37Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78321', 'http://dx.doi.org/10.26153/tsw/5408']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Multi-axis Deposition

Process Planning for Solid Freeform Fabrication Based on Laser-Additive Multi-axis Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/61a1e414-619b-4460-9e98-bdebf43772c8/download

null

This paper describes a new approach for rapid prototyping based on volumetric skeletonization. Contrary to most of the popular techniques for Solid Freeform Fabrication (SSF) based on 2-1/2 -axis layering as planar slices, this approach suggests the growth of the component along all three coordinate axes. While this approach offers many advantages in terms of the elimination of the support structures for the reduction of the staircase effects and the elimination of various post processes for the functional parts, this approach also offers challenges towards process planning. For various complicated shapes it may not be possible to generate the required shape using this approach; however, a hybrid approach which also incorporates the deposition by layers, may offer an optimum solution. Preliminary results are based on the successful laser-based additive deposition along multiple g-vectors. The material properties and the problems of possible porosities are still to be investigated. Advantages, process planning, applications, experimental results, and the challenges of this new method are the subject of this paper.

This work was financially supported by THECB (Texas Higher Education Coordinating Board) Grants 003613-0022-1999 and 003613-0016-2001, NSF (National Science Foundation) Grants DMI-9732848 and DMI-9809198 and by the US Department of Education Grant P200A80806-98.

null

['Lynn, Charity M.', 'West, Aaron', 'Rosen, David W.']

2019-02-22T17:24:03Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73462', 'http://dx.doi.org/10.26153/tsw/612']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['CAD', 'Stereolithography']

A Process Planning Method and Data Format for Achieving Tolerances in Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8d38cdd9-c084-419a-9c85-457f4e2f9213/download

null

When building parts in a stereolithography apparatus (SLA), the user is faced with many decis!ons regarding the setting of process variables. To 'achieve a set of tolera~ces as closely as pOSSIble, relationships between part geometry, tolerances, and process v~nables ~ust be understood quantitatively. This paper presents a method for SLA process plannIng that IS based on response surface methodology and multi-objective optimization, where the response surfaces capture these relationships. These response surfaces were generated by extensive design-of-experiment studies for a variety of geometries. An annotated STL data format is also presented that enables the inclusion of tolerance and surface information in fatetted representations. Application of the data format and process planning method is illustrated on one part.

null

['Jariwala, Amit S.', 'Jones, Harrison', 'Kwatra, Abhishek', 'Rosen, David W.']

2021-10-07T15:35:45Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88483', 'http://dx.doi.org/10.26153/tsw/15417']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['Exposure Controlled Projection Lithography', 'process planning', 'lens shaped structure', 'flat transparent substrates']

Process Planning Method for Exposure Controlled Projection Lithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/88b211a5-c463-436e-b8ed-33b948ee16d0/download

University of Texas at Austin

An Exposure Controlled Projection Lithography (ECPL) process with the ability to cure lens shaped structures on transparent substrates is presented. This process can be used to create microlenses and micro fluidic channels on flat or curved substrates. Incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure photopolymer resin that grows progressively from the substrate surface. A resin response model which incorporates the effects of oxygen inhibition during photopolymerization is used to formulate a process planning method for ECPL. This process planning method is validated for fabricating lens shaped structure on flat transparent substrates using the ECPL system.

null

['Limaye, Ameya', 'Rosen, David']

2020-03-09T14:23:37Z

2007

Mechanical Engineering

null

['https://hdl.handle.net/2152/80183', 'http://dx.doi.org/10.26153/tsw/7202']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Mask Projection Stereolithography

Process Planning to Build Mask Projection Stereolithography Parts with Accurate Vertical Dimensions

Conference paper

https://repositories.lib.utexas.edu//bitstreams/91348463-fc1b-4de8-85f2-1151a5ff23cb/download

null

Mask Projection Stereolithography (MPSLA) is a high resolution manufacturing process that builds parts layer by layer in a photopolymer. In this paper, we formulate a process planning method to cure MPSLA parts with accurate vertical dimensions. To this effect, we have formulated and validated the “Layer cure” model that models the thickness of a cured layer as a transient phenomenon, in which, the thickness of the layer being cured increases continuously throughout the duration of exposure. We have shown that for longer durations of exposures, such as those common with MPSLA systems, cure depth varies linearly with exposure. We have also quantified the effect of diffusion of radicals on the cure depth when discrete exposure doses, as opposed to a single continuous exposure dose, are used to cure layers. Using this work, we have formulated and validated the “Print through” model that computes the extra curing that would occur when multiple layers are cured over each other. We have implemented the Print through model to simulate the profile of a down facing surface of a test part and validated the simulation result by building the test part on our MPSLA system.

null

['Niino, Toshiki', 'Oizumi, Shunsuke', 'Sato, Kazuki']

2021-09-23T22:57:56Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88049', 'http://dx.doi.org/10.26153/tsw/14990']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['laser sintering process', 'inorganic filler', '3D tissue engineering scaffold']

Process Resolution of Laser Sintering Process Using Plastic Powder Containing Inorganic Filler at a High Rate

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e801ef41-373a-460c-8db3-6e9fe733cbcb/download

null

Research is being performed on a laser sintering process in which inorganic filler is employed as porogen at a high content to fabricate highly porous three dimensional tissue engineering scaffold. Previously, the scaffold, which included capillary like flow channel network, was used in cell culture test, but obtained cell density was limited due to insufficient fineness of the network structure. In the scaffold fabrication the author experienced degradation of process resolution when inorganic filler was introduced at a high content, but reasons for the low resolution has not been cleared. This paper investigates the dominating cause of the low resolution. Discussion is focused on effect of optical and thermal properties of filler. Experiments using transparent and opaque fillers are performed, and existence of dominating effect of difference in the optical property is denied. Experiments using thermally conductive solid filler and insulating hollow filler is performed, and it is concluded that temperature conductivity is dominating on process resolution.

null

['Schmidt, J.', 'Dechet, M.A.', 'Gómez Bonilla, J.S.', 'Bück, A.', 'Peukert, W.']

2021-11-18T01:37:25Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90395', 'http://dx.doi.org/10.26153/tsw/17316']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['process routes', 'process chains', 'blend powders', 'polybutylene terephthalate-polycarbonate', 'PBT-PC', 'selective laser sintering']

Process Routes Towards Novel Polybutylene Terephthalate – Polycarbonate Blend Powders for Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e9515b14-1f78-4090-a2ed-b30a5bb3a976/download

University of Texas at Austin

Additive manufacturing techniques, such as powder bed fusion (PBF) of polymers, often referred to as laser sintering (LS) or selective laser sintering (SLS), generate components directly from a CAD data set without using a specific mold. The range of materials commercially available for SLS merely includes some semi crystalline polymers, mainly polyamides. In this contribution two process chains to produce polybutylene terephthalate (PBT) – polycarbonate (PC) blend particles and the respective dependencies of product characteristics on process parameters are addressed. In the first recently proposed approach, blend powder systems are produced via co-comminution of PBT and PC in a planetary ball mill and subsequent thermal rounding of the obtained comminution product. This approach is compared to a route, where blend particles are obtained by agglomeration of comminution products of the respective polymers obtained by wet grinding and subsequent thermal rounding.

null

['Birnbaum, Andrew', 'Aggarangsi, Pruk', 'Beuth, Jack']

2019-11-20T16:51:21Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78483', 'http://dx.doi.org/10.26153/tsw/5568']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Process Scaling

Process Scaling and Transient Melt Pool Size Control in Laser-Based Additive Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a7d3a262-5f90-4fdc-963b-1705290f5f01/download

null

This modeling research considers two issues related to the control of melt pool size in laser-based additive manufacturing processes. First, the problem of process size scale is considered, with the goal of applying knowledge developed at one processing size scale (e.g. the LENSTM process, using a 500 watt laser) to similar processes operating at larger scales (e.g. a 3 kilowatt system under development at South Dakota School of Mines and Technology). The second problem considered is the transient behavior of melt pool size due to a step change in laser power or velocity. Its primary application is to dynamic feedback control of melt pool size by thermal imaging techniques, where model results specify power or velocity changes needed to rapidly achieve a desired melt pool size. Both of these issues are addressed via a process map approach developed by the authors and co-workers. This approach collapses results from a large number of simulations over the full range of practical process variables into plots process engineers can easily use.

This research was supported by the National Science Foundation Division of Design, Manufacture and Industrial Innovation, through the Materials Processing and Manufacturing Program, award number DMI-0200270.

null

['Brice, C.A.', 'Schwendner, K.l.', 'Mahaffey, D.W.', 'Moore, E.H.', 'Fraser, H.L.']

2019-03-15T16:13:50Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73687', 'http://dx.doi.org/10.26153/tsw/829']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['manufacturing', 'technology']

Process Variable Effects on Laser Deposited Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bf86ec6d-f87a-48ce-9c8b-c0a3c7ac3eca/download

null

An initial study ofthe processing parameters affecting deposition quality ofTi-6AI-4V was conducted using the LENSTM direct laser deposition system. The significant number ofprocess variables presents a problem in determining relative effects. A few ofthe easily identifiable variables were isolated and the deposits were characterized qualitatively by comparison oflayer adhesion, porosity, and dimensional accuracy. These characteristics were compared for each deposit while processing variables such as laser power, travel speed, and hatch spacing were varied. The results led to the development of a set of optimum processing conditions that produce a quality deposit.

null

['Geis, J.', 'Reichwein, J.', 'Merschroth, H.', 'Kirchner, E.', 'Weigold, M.']

2023-03-29T16:27:38Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117681', 'http://dx.doi.org/10.26153/tsw/44560']

eng

2022 International Solid Freeform Fabrication Symposium

Open

L-PBF

Process-controlled Grading of the Young's Modulus of AlSi10Mg Components Using L-PBF

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1d95af48-dcf6-44bc-8d5a-9f805f93e18d/download

null

Laser Powder Bed Fusion (L-PBF) increases freedom in the design of components and is therefore well suited for the manufacturing of complex geometries tailored to their function. In addition, it is possible to influence the microstructural characteristics of the components by varying the process parameters during the L-PBF process. This allows shifting the load from areas with high stresses to less heavily loaded areas in order to exploit the full potential of the material. For this purpose, the process window in which the Young‘s modulus of the material AlSi10Mg can be varied was investigated. Subsequently, test geometries were analyzed by finite element method with respect to their critical component areas and a design for grading the Young‘s modulus to distribute stress more uniformly was developed. These specimens were then manufactured and compared with components manufactured using homogeneous parameters.

null

['Budde, L.', 'Schwarz, N.', 'Hermsdorf, J.', 'Kaierle, S.', 'Overmeyer, L.']

2024-03-26T23:21:30Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124448', 'https://doi.org/10.26153/tsw/51056']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['direct energy deposition', 'laser deposition', 'wiring', 'alloy', 'additive manufacturing']

PROCESS-INTEGRATED ALLOY ADJUSTMENT IN LASER DEPOSITION WELDING WITH TWO WIRES

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c2c92688-ea4d-4ae1-a1ca-278ec2340a70/download

University of Texas at Austin

For Direct Energy Deposition (DED) with wire as filler material, the material selection is mostly limited to commercially available welding wires. This limits the achievable material properties for cladding and Additive Manufacturing purposes. Using a coaxial deposition welding head, in which two different wires can be fed and controlled individually, the alloy composition can be adjusted in the common process zone in-situ. In this study, the two wire materials AISI 316L and ER 70S-6 are used in different mixing ratios to fabricate single weld seams. The different mixing ratios are achieved by varying the wire feed rates. The material content in the weld is varied between 0% and 100% in 20% steps. The weld seams are examined with regard to the distribution of alloying elements, hardness and microstructure. Homogeneous mixing of the two materials was achieved at all mixing ratios. At a content of 40% or more of ER 70S-6 in the weld seam, there was a drastic change in the microstructure and a significant increase in hardness. The microstructure changed from austenitic to ferritic-pearlitic, which was accompanied by an increase in hardness from 170 HV0.1 to 428 HV0.1.

null

['Agarwal, Kuldeep', 'Houser, Matthew', 'Vangapally, Sairam', 'Vulli, Arun Kumar']

2021-11-02T15:49:01Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89834

eng

2017 International Solid Freeform Fabrication Symposium

Open

['nylon-fiberglass', 'process parameters', 'mechanical properties', 'Taguchi design of experiments', 'design of experiments', 'additive manufacturing']

Process-Property Relationships in Additive Manufacturing of Nylon-Fiberglass Composites Using Taguchi Design of Experiments

Conference paper

https://repositories.lib.utexas.edu//bitstreams/57e94b15-b829-4266-b50a-e95eb3b2163d/download

University of Texas at Austin

Composite Filament Fabrication (CFF) process, similar to Fused Deposition Modeling (FDM) can extrude a fiber along with a plastic. The process has two nozzles, one that can extrude Nylon and another that can extrude a fiber such as Fiberglass, Kevlar or Carbon Fiber. The mechanical properties of the parts produced by this process are dependent on the process parameters. To determine the effect of these process parameters and design parts for optimal properties, the relationship needs to be determined. This research works with Nylon-Fiberglass composite material. This study focuses on five different process parameters and their effect on mechanical properties such as tensile strength, elastic modulus and elongation to fracture. 36 experiments based on Taguchi design of experiments methodology are conducted and the analysis of variance of the results is used to find the important parameters. The results show that some process parameters are more significant than others in affecting the mechanical properties. It is found that the fiber volume % in the composite plays the most significant role in the mechanical properties.

null

['Lado, Lionardo', 'Ataollahi, Saeed', 'Yadollahi, Aref', 'Mahtabi, Mohammad J.']

2023-01-26T15:25:54Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117316', 'http://dx.doi.org/10.26153/tsw/44197']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Microstructure-sensitive fatigue', 'Additive manufacturing', 'Ti-6Al-4V', 'EBM', 'LENS', 'SLM']

Process-Specific Microstructure-Sensitive Modeling of Fatigue in Additively Manufactured Ti-6Al-4V Alloys

Conference paper

https://repositories.lib.utexas.edu//bitstreams/341f7b4e-c1c1-45f0-acd1-7d14392a57be/download

null

Thanks to its high strength-to-weight ratio and corrosion resistance, Ti-6Al-4V has gained a lot of attention in additive manufacturing (AM) of complex parts with aerospace and medical applications. The realistic loading condition in these applications is mostly cyclic, thus fatigue failure is the main mode of failure. On the other hand, due to presence of local defects in the current state of AM materials, the main challenge with AM of metallic parts is their fatigue resistance and durability, being much lower than the conventional counterparts. In this study, a simplified microstructure-sensitive fatigue (MSF) approach was developed to model the fatigue life of AM Ti-6Al-4V specimens by incorporating microstructural features and defect properties, such as grain size, pore size and pores nearest neighbors. The studied AM methods include Laser Engineered Net Shaping (LENS), Electron Beam Melting (EBM), and Selective Laser Melting (SLM). Each of these processes use different approaches in constructing the three-dimensional object, yielding in different microstructure of the final part. For this work, microstructural data were collected from previous experimental studies. Scanning Electron Microscopy (SEM) images were used to examine the fracture surfaces of the AM specimens and determine the defects responsible for fatigue failure. With an emphasis on the microstructurally small crack growth, model parameters were calibrated for fatigue data for different AM processes, while keeping process-independent parameters as constant. The results showed that a simplified MSD fatigue model with limited number of process-dependent governing parameters can be calibrated for each set of data.

null

['Lado, Lionardo', 'Ataollahi, Saeed', 'Yadollah, Aref', 'Mahtabi, Mohammad J.']

2023-01-09T19:31:58Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117171', 'http://dx.doi.org/10.26153/tsw/44052']

null

2022 International Solid Freeform Fabrication Symposium

Open

['microstructure-sensitive fatigue', 'Additive manufacturing', 'Ti-6Al-4V', 'EBM', 'LENS', 'SLM']

Process-specific Microstructure-sensitive Modeling of Fatigue in Additively Manufactured Ti-6Al-4V Alloys

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ccf1e46e-d840-4e88-97a6-01692f350777/download

null

Thanks to its high strength-to-weight ratio and corrosion resistance, Ti-6Al-4V has gained a lot of attention in additive manufacturing (AM) of complex parts with aerospace and medical applications. The realistic loading condition in these applications is mostly cyclic, thus fatigue failure is the main mode of failure. On the other hand, due to presence of local defects in the current state of AM materials, the main challenge with AM of metallic parts is their fatigue resistance and durability, being much lower than the conventional counterparts. In this study, a simplified microstructure-sensitive fatigue (MSF) approach was developed to model the fatigue life of AM Ti-6Al-4V specimens by incorporating microstructural features and defect properties, such as grain size, pore size and pores nearest neighbors. The studied AM methods include Laser Engineered Net Shaping (LENS), Electron Beam Melting (EBM), and Selective Laser Melting (SLM). Each of these processes use different approaches in constructing the three-dimensional object, yielding in different microstructure of the final part. For this work, microstructural data were collected from previous experimental studies. Scanning Electron Microscopy (SEM) images were used to examine the fracture surfaces of the AM specimens and determine the defects responsible for fatigue failure. With an emphasis on the microstructurally small crack growth, model parameters were calibrated for fatigue data for different AM processes, while keeping process-independent parameters as constant. The results showed that a simplified MSD fatigue model with limited number of process-dependent governing parameters can be calibrated for each set of data.

null

['Karg, M.', 'Ahuja, B.', 'Kuryntsev, S.', 'Gorunov, A.', 'Schmidt, M.']

2021-10-12T22:50:12Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88762', 'http://dx.doi.org/10.26153/tsw/15696']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Laser Beam Melting', 'powder bed', 'aluminum-copper alloys', 'AW-2022', 'AW-2024', 'Additive Manufacturing']

Processability of high strength Aluminum-Copper alloys AW-2022 and 2024 by Laser Beam Melting in Powder Bed

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5b3206b3-fd34-4901-9040-5398be5af7ac/download

University of Texas at Austin

Additive Manufacturing offers geometric freedom excellently suited for topology optimized light weight designs. Ideally these should be produced from materials of high strength to weight ratio such as aluminium-copper alloys. Yet these are considered unsuitable for welding. With Laser Beam Melting of Metals in powder bed (LBM), the only class of aluminium alloys widely processed is that of aluminium-silicon alloys, which are easily weldable and castable, too. In this contribution we present results of LBM high-strength aluminium-copper alloys AW-2022 and AW-2024 under variation of laser power, scan speed and hatch distance. We achieved relative densities well above 99 %. We analyzed thin walls, compared process windows as well as microstructures observed using etched metallographic microsections. We analyzed the chemical constitution of powders and produced samples using ICP-OES.

null

['Singer, C.', 'Platt, S.', 'Horn, M.', 'Binder, M.', 'Piechotta, M.', 'Wegner, J.', 'Kleszczynski, S.', 'Seidel, C.', 'Witt, G.', 'Schilp, J.']

2021-12-06T21:31:41Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90678', 'http://dx.doi.org/10.26153/tsw/17597']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['processability', 'laser-based powder bed fusion', 'PBF-LB', 'soda-lime glass']

Processability of Soda-Lime Glass in Laser-Based Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/97f8cbce-21a2-46b6-a7fe-0cd65b06288e/download

University of Texas at Austin

Processing of electrically insulating materials with high temperature resistance is a major challenge in laser-based powder bed fusion (PBF-LB). Glasses form a promising material class, which also offers the potential for manufacturing optical or electronic components while having high chemical resistance. Therefore, this paper investigates the processability of soda-lime glass in conventional PBF-LB machines using Yb:YAG and CO2 lasers. Firstly, the flow properties and particle shape of the glass powder were inspected. Secondly, the influence of laser power, scan velocity, layer height and hatch distance as well as exposure pattern on the manufacturing of single tracks, single layers, and finally 3- D-parts was investigated. Furthermore, an increase of the temperature of the platform range between 250 to 600 °C resulted in increasing relative density. Despite the higher absorptivity of soda lime glass in the wavelength range of the CO2 laser, manufacturing of 3-D-parts was only possible using a Yb:YAG laser due to insufficient laser power of the former beam source.

null

['Gupta, Ankit', 'Hasanov, Seymur', 'Fidan, Ismail']

2021-11-18T16:37:58Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90420', 'http://dx.doi.org/10.26153/tsw/17341']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'PMC', 'SF', 'tensile strength', '3D printing', 'microhardness']

Processing and Characterization of 3D-Printed Polymer Matrix Composites Reinforced with Discontinuous Fibers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/39ef9c26-d12f-42c2-9202-0d59534b3d26/download

University of Texas at Austin

The objective of this study is to fabricate discontinuous fiber (short fiber) reinforced polymer matrix composite material (CM) by additive manufacturing (AM) technology using single extruder 3D printer. For this study, short carbon fibers (diameter = 7.2μm, length = 150μm) reinforced filaments were extruded with fiber concentrations of 3% - 7.5% in volume. Input process parameters used for 3D printing to obtain good quality short carbon fiber (SCF) reinforced polymer specimens are reinforcement percentage and printing speed by fixing nozzle temperature, layer thickness, bed temperature and print orientation. It was analyzed that the surface characteristics and mechanical performance of 3D printed samples are greatly influenced by varying input process parameters. Scanning electron microscopy was performed to observe microstructural behavior of 3D printed samples. Tensile strength, ductility, and toughness were examined to validate the adhesiveness of the matrix and reinforcement. From the microhardness test, it was observed that the hardness properties are significantly affected by increasing the reinforcement percentage. The results obtained in this study could be quite useful in fabricating polymer matrix composites (PMCs) with improved overall characteristics for applications in automotive industry and medical field.

null

['Jiang, Kaiyi', 'Guo, Yanling', 'Bourell, David L.']

2021-10-13T19:41:51Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88772', 'http://dx.doi.org/10.26153/tsw/15706']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'eucalyptus-polyamide 12', 'EPA12', 'wood powder']

Processing and Characterizations of Eucalyptus-PA12 Composite by Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7209b72b-016d-4828-b2fb-b9247893158c/download

University of Texas at Austin

To meet the existing requirements to make Laser Sintering (LS) technology more economical and environmentally friendly, a new type of low cost sustainable material (eucalyptus-polyamide 12 (EPA12) composite) was developed. This paper presents initial research into the LS PA12 with wood powder additions. EPA12 mixed in a ratio of 1:2 by volume has been shown to be extremely processable by LS. Before sintering experiments, thermal conductivity (which is an important component in understanding and optimizing the processing of laser sintering EPA 12) was measured. During LS processing, a variety of laser powers were chosen to investigate the effect of the energy input on the densification, mechanical properties and forming accuracy of the material. The dispersion of eucalyptus in the LS specimens of the composite powder was examined by scanning electron microscopy (SEM). The microstructure of sintered EPA12 was observed. By comparing the microstructures, observable differences based on varying levels of laser power were also present. The maximum tensile strength and the flexure strength of prototypes are 3.7 MPa and 38 MPa, respectively. These values increased from the minimum with increased energy input. On the contrary, the forming accuracy was high at a relatively low laser power.

null

['Xiong, Y.', 'Smugeresky, J. E.', 'Lavernia, E. J.', 'Schoenung, J. M.']

2020-03-10T17:39:57Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80237', 'http://dx.doi.org/10.26153/tsw/7256']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Laser Engineered Net Shaping

Processing and Microstructure of WC-CO Cermets by Laser Engineering Net Shaping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2481f2cc-3d15-41ff-87eb-cd06c64142f6/download

null

Submicron-sized tungsten carbide-cobalt (WC-Co) powder and nanostructured WC-Co powder were applied to make thick wall samples by the Laser Engineered Net Shaping (LENS®) process. It was found that decomposition and decarburization of WC was limited during laser deposition because of the features of the LENS® process: high cooling rate, short heating time, and low oxygen concentration. The effects of working distance, as well as laser power, powder feed rate, and traverse speed on microstructure were studied in this paper. Thermal behavior leading to the observed microstructures that result from the variations in the processing parameters was investigated in detail

null

['He, Yinfeng', 'Kilsby, Sam', 'Tuck, Chris', 'Wildman, Ricky', 'Christie, Steven', 'Edmonson, Steven', 'Yang, Hongyi']

2021-10-07T17:38:53Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88491', 'http://dx.doi.org/10.26153/tsw/15425']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['biodegradable Polycaprolactone', '3D printing', 'biodegradable processing', 'PCL']

Processing Biodegradable Polycaprolactone through 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/71065317-cec8-4c12-9553-80ec068f62e8/download

University of Texas at Austin

An initial study of processing biodegradable Polycaprolactone (PCL) through 3D printing technology was conducted using Fujifilm Dimatix DMP-2800 material printer. The aim of this work was to investigate a potential method of preparing and processing biodegradable polycaprolactone through 3D printing. PCL inks with a concentration of 5wt% and 10wt% were prepared to investigate their processability. The influences of waveform peak height, time gap, printing voltage, droplet velocity, substrate temperature and droplet spacing on PCL ink droplet formation as well as final deposition quality were investigated. Multi-layer PCL structures were printed and characterized with the geometric quality of deposited PCL measured using a Talysurf 2000 and Bruker ContourGT-I. It was found that PCL solvent ink can reach relative stable droplet formation and deposition when plate temperature was 30 ºC and droplet velocity was 6m/s. Printed PCL solvent ink showed ‘coffee ring’ effect after solidification. When deposition droplet spacing equals to 40µm, printed PCL film showed the lowest surface roughness.

null

['Spierings, A.B.', 'Bauer, T.', 'Dawson, K.', 'Colella, A.', 'Wegener, K.']

2021-10-20T22:40:25Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89379

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'additive manufacturing', 'ODS materials', 'microstructure']

Processing ODS Modified IN-625 Using Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e80a9e3d-acf7-45e5-875c-5e7d07dd6852/download

University of Texas at Austin

Increasing the operating temperatures of power plant turbine generators is a universal method to increase the efficiency of steam and gas turbines. However, operating a plant at higher temperatures poses extreme challenges to the materials used, especially regarding oxidation, creep, thermal fatigue- and stress-corrosion cracking. The EU-OXIGEN project addresses these issues by the development of novel processing routes for ODS-modified materials, as this class of materials offers exceptionally high temperature strength, oxidation and corrosion resistance at temperatures exceeding 900°C. Additive manufacturing processes such as Selective Laser Melting are considered to enable their successful processing. First results on density of SLM-processed, mechanically alloyed ODS-modified Inconel-625 superalloy powders, are presented and compared to the processing conditions and results of gas atomized conventional Inconel-625 powders. Whereas for IN625 a wide and stable processing window was found, significant differences for the ODS variant in terms of the required laser energy input to reach density values >99% are found. Microstructural analysis of precipitates lead to the conclusion that the milling process for ODS variant is key to achieve good quality materials and results.

null

['Bose, Susmita', 'Avila, Marisol', 'Bandyopadhyay, Amit']

2019-02-27T17:39:20Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73507', 'http://dx.doi.org/10.26153/tsw/657']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['SFF', 'bioceramic implants']

Processing of Bioceramic Implants Via Fused Deposition Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/efcd328a-4100-4a54-afb1-ed94f0443336/download

null

Porous ceramic structures have long been a subject of investigation as bone sl..bstitute. Most of these porous structures are typically made by techniques that result .randomly arranged pores with a wide variety of pore sizes. In recent years, SFF methods are being used for the fabrication of porous bioceramic implants. Porous ceramic structures have been fabricated using indirect route where a .polymeric mold is fitst created via fused deposition process. The mold was then infiltrated with ceramic slurry, dried. and ·then subjected to a binder bum out and sintering cycle. In this paper, processing of 3D honeycomb porous alumina ceramic structures and some.initial mechanical properties for bone implants will be discussed.

null

['Greer, Chad', 'McLaurin, Juli', 'Ogale, Amod A.']

2018-11-14T17:43:51Z

1996

Mechanical Engineering

doi:10.15781/T2028PZ9Z

http://hdl.handle.net/2152/70248

eng

1996 International Solid Freeform Fabrication Symposium

Open

['ADPU', '3D photolithography', 'pure resins']

Processing of Carbon Fiber Reinforced Composites by Three Dimensional Photolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a72cacbe-deb2-4232-ba93-44fae8bc8296/download

null

The reinforcement of photoresins with continuous carbon fibers is discussed in this paper. The processing was conducted in an automated desktop photolithography unit (ADPU) developed and built in-house. Continuous fibers were added in situ to the photoresin to obtain composite samples containing over 20 vol% of the fibers. The tensile strength of these composites improved by at least a factor of 2 as compared to that of the pure photoresins. It is also noted that the photoresin could be partially cured to develop sufficient green strength in the composite samples even though the fibers are opaque to ultraviolet radiation. These results indicate the potential of this technique to produce functional composite components in conjunction with a 3-D photolithography apparatus.

null

['Campanelli, Carlo', 'Wildman, Ricky D.', 'Tuck, Christopher J.']

2021-11-11T16:13:08Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90232', 'http://dx.doi.org/10.26153/tsw/17153']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['part processing', 'fluoropolymers', 'laser sintering']

Processing of High Performance Fluoropolymers by Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/33dcf6a0-4114-4276-8ddb-50cf40a12c82/download

University of Texas at Austin

One of the main limitations of laser sintering (LS) is its narrow material portfolio. Fluoropolymers are a family of polymers with outstanding properties such as wide service temperatures (−260 °C - +260 °C), excellent resistance to chemicals, sunlight, flames, and weathering without the addition of stabilizers, plasticizers or fillers. In this study, fluoropolymers such as perfluoroalkoxy (PFA) and polychlorotrifluoroethylene (PCTFE) have been used in laser sintering. PFA and PCTFE have melting temperatures of 304 °C and 210 °C respectively which make them challenging to process. Our results demonstrate the feasibility of these materials in LS and that warping was the major issue encountered due to the relatively low powder bed temperature of ∼182 °C. We illustrate how particle size, additives, and thermal conditioning affect the powder flow and how the warping can be decreased by utilizing a modified build plate, and different scan strategies and part orientations. Flat sheets were successfully produced with potential use in membrane-based applications.

null

['Spierings, A.B.', 'Leinenbach, C.', 'Kenel, C.', 'Wegener, K.']

2021-10-13T21:33:31Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88787', 'http://dx.doi.org/10.26153/tsw/15721']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'hybrid materials', 'metal matrix composite', 'diamonds', 'microstructure']

Processing of Metal-Diamond-Composites using Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b4801699-6900-421b-accc-ff3f3e8ad7d9/download

University of Texas at Austin

Powder-bed based additive manufacturing processes such as Selective Laser Melting (SLM) offer a huge degree of freedom, both in terms of part design and material options. In that respect, mixtures of different materials in powder form can offer new ways for the manufacture of materials with tailored properties for special applications. A promising field of applications is e.g. additive manufacturing of metal-based cutting or grinding tools with incorporated hard phases. For that purpose a feasibility study was performed concerning SLM of a Cu-Sn-Ti alloy powder, which is usually used for active brazing of ceramics and superhard materials, containing 10-20 vol.-% artificial, Ni-coated mono-crystalline diamonds. Even though the processing parameters were not yet optimized, stable specimens containing intact diamonds could be produced. First results on density and microstructure are presented and discussed.

null

['Safari, A.', 'Danforth, S. C.', 'Panda, R. K.', 'McNulty, T. F.', 'Mohammadi, F.', 'Bandyopadhyay, A.']

2018-12-05T20:00:15Z

1997

Mechanical Engineering

doi:10.15781/T2S17TC9D

http://hdl.handle.net/2152/71408

eng

1997 International Solid Freeform Fabrication Symposium

Open

['Piezoelectricity', 'centrosymmetric']

Processing of Novel Piezoelectric Transducers Via SFF

Conference paper

https://repositories.lib.utexas.edu//bitstreams/52dc9af2-25be-4731-8e53-3b7b46a396a5/download

null

Piezoelectric ceramics and ceramic/polYmer composites exhibiting conventional and novel designs were fabricated using Solid Freeform Fabrication (SFF) techniques. SFF is used to develop and optimize numerous transducer designs with simple and complex shapes without using any part specific tools or dies. Fused Deposition ofCeramics (FDC), Fused Deposition Modeling (FDMTM), and Sanders Prototyping (SPI) techniques were used to develop lead-zirconate-titanate (PZT) novel ceramic structures via: (1) direct fabrication and (2) indirect fabrication routes. For the direct fabrication route, green PZT ceramic preforms consisting of 50-55 volume fraction of powder with RU binders were prepared by FDC and used for piezocomposites. For the indirect route, SPI and FDMTM techniques were used build the polymer prototype or mold, and the ceramic parts were fabricated from the molds/prototypes using (a) lost mold and (b) soft tooling processes. Among the various ceramics and composites processed via the direct and indirect processes are dome shaped actuators, 3D honeycomb, ladder, annular, rods, tubes and various oriented PZT fiber structures. This presentation will review the processing routes for design, development and optimization of piezoelectric ceramics and ceramic/polYmer composites for transducer applications.

null

['Bandyopadhyay, A.', 'Panda, R. K.', 'Janas, V. F.', 'Danforth, S. C.', 'Safari, A.']

2018-11-14T17:13:17Z

1996

Mechanical Engineering

doi:10.15781/T2MS3KM76

http://hdl.handle.net/2152/70243

eng

1996 International Solid Freeform Fabrication Symposium

Open

['FDC', 'Piezolectric materials', 'polymer materials']

Processing of Piezocomposites via Solid Freeform Fabrication (SFF)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/45613c8a-89fe-4163-9deb-d8837023bdf7/download

null

Fused Deposition and Sanders prototyping were used to manufacture PZT-polymer composites with various architecture for transducer applications. Two separate processing routes, direct and indirect, were utilized to make these composites. In the direct processing route, Fused Deposition of ceramics (FDC) was used to form green ceramic structures. For the indirect processing route, molds ofthe negative of the structures were made using FDM™ and Sanders prototyping techniques. Molds were infiltrated with a PZT slurry and dried. These structures were subjected to a binder bum out cycle to remove the mold polymer and binder. Structures were sintered and infiltrated with an acoustic epoxy, cut, polished and poled for electro-mechanical characterization. Among the various composites produced via the direct and indirect processes were: 3D honeycomb, 3-3 ladder, 2-2 annular and 1-3 rods. Composites with features as fine as 50 f.lm were manufactured and characterized. Properties ofpiezoelectric composites produced by SFF techniques compared to conventionally processed composites.

null

['Streek, A.', 'Regenfuss, P.', 'Ullmann, F.', 'Hartwig, L.', 'Ebert, R.', 'Exner, H.']

2020-02-28T21:16:04Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80123', 'http://dx.doi.org/10.26153/tsw/7144']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Laser micro sintering

Processing of Silicon Carbide by Laser Micro Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6421febb-2f3c-4011-b6b8-d9ece4487483/download

null

Silicon carbide – a solid with covalent bonds - is conventionally synthesized via the Acheson process. Usually solid bodies of silicon carbide with definite shapes are generated from the grained material via hot isostatic pressing or liquid phase sintering. Both processes are conducted under well-controlled temperature regimes. Applying the freeform fabrication technique “Laser Micro Sintering” poses a big challenge to experimental skill due to the nonequilibrium conditions that are characteristic features of laser material processing. Successive layers SiC layers with a thickness of 1μm were processed with coherent radiation of 1064 nm. The specific behavior of two different silicon carbide powders - one of them blended with additives - are reported along with interpretational approaches.

null

['Das, Suman', 'Wohlert, Martin', 'Beaman, Joseph J.', 'Bourell, David L.']

2019-02-26T16:46:25Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73485', 'http://dx.doi.org/10.26153/tsw/635']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['SFF', 'Direct fabrication']

Processing of Titanium Net Shapes by SLS/HIP

Conference paper

https://repositories.lib.utexas.edu//bitstreams/61e29f2c-9147-4eb1-8318-af8f9a8bedb2/download

null

SLS/HIP is a hybrid direct laser fabrication method that combines the strengths of selective laser sintering (SLS) and hot isostatic pressing (HIP). SLS can produce complex shaped metal components with an integral, gas impermeable skin. These components can then be directly post-processed to full density by containerless HIP. SLS/HIP is envisioned as a rapid, low cost replacement for conventional metal can HIP processing. The advantages of freeform fabrication combined with in-situ HIP encapsulation include ability to perform containerless HIP, no adverse container-powder interactions, reduced pre-processing time, and fewer postprocessing steps compared to conventional HIP of canned parts. SLS/HIP is currently being developed for Inconel 625 superalloyand Ti-6AI-4V. This paper focuses on microstructure and mechanical properties of SLS processed and HIP post-processed Ti-6AI-4V. SLS/HIP technology for Ti-6Al-4V was demonstrated by fabricating a subscale AIM-9 missile guidance section housing to specification. This work is funded jointly by DARPA and ONR under contract N00014-95-C-0139 titled "Low Cost Metal Processing Using SLS/HIP."

null

['Khan, M.', 'Dickens, P. M.']

2020-03-11T15:31:30Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80252', 'http://dx.doi.org/10.26153/tsw/7271']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Selective Laser Melting

Processing Parameters for Selective Laser Melting (SLM) of Gold

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9f2393da-5491-42e6-b2e8-38c41e3dd57d/download

null

Research into laser processing of different metals has enabled Solid Freeform Fabrication (SFF) processes to produce parts for a wide variety of applications. However, less focus has been made on the processing of precious metals. Currently little research has been reported on the processing of precious metals and alloys using the Selective Laser Melting (SLM) process. Here we present an initial investigation into the processing of 24 carat gold (Au) powder using a SLM system. Gold powder was tested for apparent density, tap density, particle shape and size distribution. A quality check of the specimen was carried out using a Scanning Electron Microscope (SEM) for sinterability and occurrence of porosity. Significant processing parameters were also identified.

null

['Zong, G.', 'Tompkins, J.V.', 'Thissell, W.R.', 'Sajot, E.', 'Marcus, H.L.']

2018-04-17T18:55:08Z

1991

Mechanical Engineering

doi:10.15781/T22Z1364K

http://hdl.handle.net/2152/64353

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Center for Materials Science and Engineering', 'SALD', 'pyrolytic']

Processing Problems Associated with Gas Phase Solid Freeform Fabrication Using Pyrolytic Selective Area Laser Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3a43ba5e-b967-4668-85db-1017b1677e16/download

null

Concerns critical to selective area laser deposition are discussed. Variables affecting deposition rate, dimensional control, and surface uniformity are analyzed. Localized growth results in undesirable morphology, and contributing factors are cited. Catalytic powders increase nucleation rate and provide superior temperature profiles resulting in good surface uniformity. Specific process control devices are investigated.

null

['Schumacher, Christian', 'Schöppner, Volker', 'Gnaase, Stefan']

2021-11-10T21:59:12Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90190', 'http://dx.doi.org/10.26153/tsw/17111']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['short fiber-reinforced filaments', 'fiber reinforced polymers', 'fused deposition modeling', 'processing']

Processing Short Fiber-Reinforced Polymers in the Fused Deposition Modeling Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c3498048-8643-4add-87fa-e99e0bc9e492/download

University of Texas at Austin

By adding fibers to a polymer matrix, a reinforcement of the material can be achieved. Short fiber-reinforced polymers can easily be processed by the Fused Deposition Modeling (FDM) process without major modifications to the processing machine. For instance, short fiber-reinforced filaments can be processed to produce short fiber-reinforced components in the FDM process. In many other additive manufacturing processes this is not possible at this low cost. The choice of the matrix material, fiber type, fiber length and fiber orientation have a major influence on the properties of the produced component. In this paper, short fiber-reinforced filaments are processed by the FDM process. The processing properties and the resulting part properties are investigated with regard to fiber-specific influences. Additionally, the effects of different strand geometries and thus changed flow fields on the fiber orientation and mechanical part properties are investigated.

null

['Hattiangadi, Ashwin', 'Bandyopadhyay, Amit']

2019-03-13T16:22:31Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73642', 'http://dx.doi.org/10.26153/tsw/784']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['ceramic', 'Porous Hydroxyapatite']

Processing, Characterization and Modeling of Non-Random Porous Ceramic Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1674283b-653f-4d15-ac65-bda01c4c157c/download

null

Processing of non-random porous ceramic structures via fused deposition process is discussed. structures are characterized experimentally and statistically based on their compressive strength. Finite element modeling is used to understand the effect of stress concentration leading to the strength degradation ofthese brittle elastic solids.

null

['Prinz, F.B.', 'Weiss, L.E.', 'Amon, C.H.', 'Beuth, J.L.']

2018-10-05T17:07:39Z

1995

Mechanical Engineering

doi:10.15781/T20G3HH4W

http://hdl.handle.net/2152/68716

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SDM', 'CNC machining', 'SFF']

Processing, Thermal and Mechanical Issues in Shape Deposition Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/153d495c-54bc-4da7-be99-30af47781d44/download

null

An overview of Shape Deposition Manufacturing (SDM) is presented, detailing manufacturing, thermal and mechanical issues of concern in making it a commercially viable method for creating arbitrarily shaped three-dimensional metal parts. SDM is a layered manufacturing process which combines the benefits of solid freeform fabrication and other processing operations, such as multi-axis CNC machining. This manufacturing process makes possible the fabrication of multi-material layers, structures of arbitrary geometric complexity, artifacts with controlled microstructures, and the embedding of electronic components and sensors in conformal shape structures. Important issues toward the production of high quality objects are the creation of inter-layer metallurgical bonding through substrate remelting, the control of cooling rates of both the substrate and the deposition material, and the minimization of residual thermal stress effects. Brief descriptions of thermal and mechanical modeling aspects of the process are given. Because SDM involves molten metal deposition, an understanding of thermal aspects of the process is crucial. Current thermal modeling of the process is centered on the issue of localized remelting of previously deposited material by newly deposited molten droplets. Residual stress build-up is inherent to any manufacturing process based on successive deposition of molten material. Current mechanics modeling is centered on the issues of residual stress build-up and residual stress-driven debonding between deposited layers.

null

['Kempen, K.', 'Thijs, L.', 'Vrancken, B.', 'Buls, S.', 'Van Humbeeck, J.', 'Kruth, J.-P.']

2021-10-07T15:44:25Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88485', 'http://dx.doi.org/10.26153/tsw/15419']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['Additive Manufacturing', 'Selective Laser Melting', 'M2 parts', 'pre-heating', 'baseplate', 'crack-free', 'high density']

Producing Crack-Free, High Density M2 HSS Parts by Selective Laser Melting: Pre-Heating the Baseplate

Conference paper

https://repositories.lib.utexas.edu//bitstreams/03977b07-9b7b-4e54-8133-4d12ca545c18/download

University of Texas at Austin

Cracks and delamination, resulting from residual stresses are a barrier in the world of Additive Manufacturing and Selective Laser Melting (SLM) that prohibits the use of many metals in this field. By preheating the baseplate, thermal gradients are lowered and stresses can be reduced. In this work, some initial tests were performed with M2 Tool Steel. Results show that pre-heating enables the production of dense M2 parts. The influence of pre-heating on density and mechanical and physical properties is investigated. The paper shows many promising results for the production of SLM parts in materials that are very sensitive to crack formation and delamination. When using a pre-heating of 200°C, crack-free parts were produced with a relative density of 99.8%.

null

['Liou, Frank', 'Leu, Ming']

2020-03-10T16:33:22Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80227', 'http://dx.doi.org/10.26153/tsw/7246']

eng

2008 International Solid Freeform Fabrication Symposium

Open

freeform fabrication

Product Focused Freeform Fabrication Education

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9a4bf3b7-4adf-4f62-a56a-bc549bfcaa6e/download

null

Presented in this paper is our experience of teaching freeform fabrication to students at the Missouri University of Science and Technology, and to high school students and teachers. The emphasis of the curriculum is exposing students to rapid product development technologies with the goal of creating awareness to emerging career opportunities in CAD/CAM. Starting from solid modeling, principles of freeform fabrication, to applications of rapid prototyping and manufacturing in industry sponsored product development projects, students can learn in-depth freeform fabrication technologies. Interactive course content with hands-on experience for product development is the key towards the success of the program.

null

Carleberg, Per

2018-10-03T15:54:34Z

1994

Mechanical Engineering

doi:10.15781/T20R9MP3X

http://hdl.handle.net/2152/68654

eng

1994 International Solid Freeform Fabrication Symposium

Open

['SFF System', 'selective laser sintering', 'laser power and laser thickness']

Product Model Driven Direct Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9ad9b9e0-93cf-4587-9d18-12b1d9ea15ce/download

null

The input to the freeform fabrication process is essentially geometric data, raw material, material data and process parameters. Optimal process parameters depend upon current material and the part geometry. This paper describes an research approach in which all necessary input including process parameters are obtained or derived from the product model. The part geometry with its process parameters is transferred as a STEP model to the SFF system. In the SFF system this model is converted to the internal format, coupled to the process parameters. The approach is exemplified with the SLS machine from DTM as SFF system.

null

['Reiher, T.', 'Koch, R.']

2021-11-01T21:53:32Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89769

eng

2016 International Solid Freeform Fabrication Symposium

Open

['product optimization', 'topology optimization', 'part optimiization', 'additive manufacturing']

Product Optimization with and for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1d8318c8-bb2d-4a6f-be0e-9d0bb88cc6ff/download

University of Texas at Austin

Additive Manufacturing offers a great potential for the optimization of products. Therefore different approaches are feasible to exploit these potentials for elaborating optimal solutions. For example these include optimization of weight or stiffness of structural components as well as the integration of functions and other entities of assemblies. Note, however, that additive manufacturing processes have process specific limitations. Products, components and assemblies, as well as procedures for the design and production preparation must be optimized with regard to a successful additive manufacturing. The use of already known tools for the optimization and design needs to be reconsidered and adapted to the additive manufacturing. This also includes the production planning with component orientation in build chamber as well as a necessary quality management system. This paper shows several ways for product optimization with additive manufacturing, often based on topology optimization, and procedures for information gathering, decision making and shape determination for part optimization for Additive Manufacturing.

null

['Stucker, Brent E.', 'Bradley, Walter L.', 'Norasetthekul, Somchin', 'Eubank, Philip T.']

2018-11-02T16:19:53Z

1995

Mechanical Engineering

doi:10.15781/T2X05XZ21

http://hdl.handle.net/2152/69335

eng

1995 International Solid Freeform Fabrication Symposium

Open

['EDM', 'Rapid prototyping', 'tool production']

The Production of Electrical Discharge Machining Electrodes Using SLS: Preliminary Results

Conference paper

https://repositories.lib.utexas.edu//bitstreams/49cc7c9c-ce71-4908-a3b6-3b550c2e4fd2/download

null

Electrical discharge machining (EDM) has become common place in the tool and die industry as an alternative to conventional machining and now accounts for 2% ofworldwide machiningl , with a substantially greater concentration ofuse in the tool making industry.EDM has the advantage of allowing tool steel billets to be heat treated to full hardness before the cavity is produced, obviating the need for heat treatment after machining--a step that often results in the loss of dimensional accuracy due to distortion in the quenching from high temperature austenite to martensite at room temperature. Any material with less than 1 ohm-m ofelectrical resistivity, regardless ofhardness, can be machined using EDM. 1 EDM also allows the convenient production of complex shapes in the tool cavity, as complex topographies can often be more easily machined on the electrode than inside a cavity. Even certain simple shapes such as rectangular or square cavities are far easier to produce using EDM than conventional machining. EDM machining, however, is precluded from many market niches by the relatively high cost ofelectrode production In visiting with approximately sixty representatives from the EDM industry, we have learned that the cost of electrode fabrication is often greater than 50%, and sometimes as great as 80%, ofthe total cost offabricating a die using EDM. 2 ,3 The wear ratio ofthe two most commonly used electrode materials, graphite and copper, requires the use ofmultiple electrodes in the production of each cavity, because the electrode wears away and loses its initial shape too quickly. Thus, the replacement ofgraphite and copper electrodes with electrodes made ofmaterials which are more resistant to electric spark erosion would significantly improve the cost effectiveness ofEDM tool production. Many tools have multiple cavities that use a different electrode for each separate cavity because it is easier to machine several small, simply-shaped electrodes than it is to machine one large, complex electrode. This requires a greater total sink time in the EDM machine, since multiple cavities are machined sequentially rather than simultaneously. The ability to create a large, complex electrode quickly would greatly reduce the time and money spent in tool production using EDM. If the rapid prototyping technology4-7 that has emerged during the past ten years could be utilized to fabricate EDM electrodes, the cost of producing electrodes with complex shapes could be substantially reduced, and new material systems which are difficult to machine could be utilized for the electrodes. Complex electrodes capable of making multiple imprints/cavities in dies simultaneously could be fabricated just as easily as simple electrodes using rapid prototyping equipment, which would increase the precision ofthe cavities' placement relative to one another, 278 dramatically reducing the EDM machine time required. A die which might, for instance, require as many as 15 imprints, which are now done sequentially, could be done in one EDM operation, reducing the time in the EDM machine and increasing the precision of placement ofthe imprints relative to one another. 3 This would be a significant contribution to the tool and die industry. Texas A&M University has undertaken research to produce EDM electrodes using rapid prototyping. Specifically, the development of a process for rapid prototyping ofEDM electrodes, using selective laser sintering (SLS) ofpolYmer coated intermetallic powders which are subsequently infiltrated with a highly conductive metal, is being investigated.

null

['Sachs, Emanuel', 'Allen, Samuel', 'Cima, Michael', 'Wylonis, Edward', 'Guo, Honglin']

2018-11-08T15:47:25Z

1995

Mechanical Engineering

doi:10.15781/T22N5036C

http://hdl.handle.net/2152/69894

eng

1995 International Solid Freeform Fabrication Symposium

Open

['3D Printing', 'postprocessing', 'unbound powder']

Production of Injection Molding Tooling with Conformal Cooling Channels using The Three Dimensional Printing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6b53c2b4-1b22-46e9-9c6e-433a801947aa/download

null

Three Dimensional Printing is a desktop manufacturing process in which powdered materials are deposited in layers and selectively joined with binder from an ink-jet style printhead. Unbound powder is removed upon process completion, leaving a three dimensional part. Stainless steel injection molding inserts have been created from metal powder with the 3DP process. The freedom to create internal geometry by the use of the 3D-Printing process allows for the fabrication of molds with complex internal cooling passages. Tooling was developed with cooling channels designed to be conformal to the molding cavity. A finite difference simulation was constructed to study conformal channel design. A direct comparison of the mold surface temperature during the injection cycle of a 3D Printed mold with conformal channels and a mold machined with conventional straight channels was completed. The conformal passages produced with the 3DP process provide the ability to accurately control the temperature of the molding cavity throughout the process cycle. Surface temperature measurements demonstrated that the inserts with conformal cooling channels exhibited a more uniform surface temperature than the inserts machined with straight channels. Issues such as powder removal and post processing of green parts with small cooling channels were investigated.

null

['Pridham, M.S.', 'Thomson, G.A.', 'Menon, U', 'Koch, M']

2018-09-26T18:49:48Z

1994

Mechanical Engineering

doi:10.15781/T2TM72K6Q

http://hdl.handle.net/2152/68583

eng

1994 International Solid Freeform Fabrication Symposium

Open

['Laminated Prototyping', 'Laser Forming', 'Rapid Prototyping']

Production of Metal Prototypes Using a High Powered Laser Machining Centre

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7e93e72d-47e4-4d05-982a-2b8ada4eef6c/download

null

The established commercially available rapid prototyping techniques are now well known throughout the manufacturing community. They are able to produce high quality, accurate prototypes, but are limited largely to processing polymer, wax or paper materials. Where a metal part is required, then a further process step, such as investment casting using the prototype part as a pattern is required. As a further point most of the above systems are high capital cost dedicated pieces of equipment. This paper describes the use of laser machining centres as rapid prototyping tools in the areas of, laminated prototyping, using both paper and metal, and laser forming.

null

['Schmidt, Jochen', 'Gómez Bonilla, Juan', 'Sachs, Marius', 'Lanz, Lydia', 'Wudy, Katrin', 'Wirth, Karl-Ernst', 'Drummer, Dietmar', 'Peukert, Wolfgang']

2021-10-28T14:28:34Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89649

eng

2016 International Solid Freeform Fabrication Symposium

Open

['process route', 'glass composites', 'polybutylene terephthalate', 'selective laser sintering']

Production of Polybutylene Terephthalate Glass Composite Powders and Characterization for Processing in Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ac4ed357-89cb-4aba-bb8b-b0c19aaae78a/download

University of Texas at Austin

Additive manufacturing techniques, such as selective laser melting of plastics, generate components directly from a CAD data set without using a specific mould. The range of materials commercially available for selective laser sintering merely includes some semi crystalline polymers, mainly polyamides. In this contribution a recently proposed process route (grinding and rounding) which allows for production of spherical polymer micro particles is applied to glass-filled polybutylene terephthalate. Composite powders of good flowability are obtained. Process relevant material characteristics like powder flowability and thermal properties are investigated. The influence of filler content on grinding behavior and resulting materials properties is discussed.

null

['Dalgarno, K.W.', 'Stewart, T.D.', 'Childs, T.H.C.']

2019-09-20T18:30:45Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75928', 'http://dx.doi.org/10.26153/tsw/3027']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Polymer

Production Tooling for Polymer Components Via The DTM RapidSteel Process 125

Conference paper

https://repositories.lib.utexas.edu//bitstreams/565c6381-af8a-4c0c-8388-ed3e2e4528c9/download

null

This paper reports the results of a study examining the potential of layer manufacturing processes to deliver production tooling for polymer manufacture, with the DTM RapidSteel process used to provide the tooling. Four main areas were addressed during the study: wear, mechanical strength, accuracy, and productivity, with each area examined through analytical studies and industrial trials. An overview of the results from both the analytical and in company experimental studies are presented.

null

['Jahnke, U.', 'Bornefeld, P.A.', 'Koch, R.']

2021-11-01T22:31:25Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89784

eng

2016 International Solid Freeform Fabrication Symposium

Open

['traceability', 'markings', 'product marking', 'additive manufacturing', 'Industry 4.0']

Production-Integrated Markings for Traceability of AM Parts in the Context of Industry 4.0

Conference paper

https://repositories.lib.utexas.edu//bitstreams/738ddd09-9213-4178-b951-812aead63bd3/download

University of Texas at Austin

Traceability is often mentioned as one fundamental requirement to reach the vision of Industry 4.0, the next industrial revolution. As Additive Manufacturing (AM) is a technology with high relevance in the scope of Industry 4.0 this paper focuses on production-integrated markings for traceability of additively manufactured parts. Even industries that are not focusing on products with critical functionality using markings for quality management and liability exclusion can benefit a lot from identifiability of products. Markings can be understood as a kind of individualization of parts. As individualization does not increase production costs when using AM and the effort for integration of markings can be minimized by software in particular for high batch production, product marking should be an obligatory process step. This paper comprises various applications that can be achieved due to markings as well as different ways to embed a marking at least partly automatically.

null

['Khanzadeh, Mojtaba', 'Jafari Marandi, Ruholla', 'Tootooni, M. Samie', 'Bian, Linkan', 'Smith, Brian', 'Rao, Prahalad']

2021-10-28T19:26:37Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89675

eng

2016 International Solid Freeform Fabrication Symposium

Open

['geometric accuracy', 'self-organizing map', 'additive manufacturing']

Profiling and Optimizing the Geometric Accuracy of Additively Manufactured Components via Self-Organizing Map

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1d0360f2-5953-4c20-b669-243072a226a4/download

University of Texas at Austin

One main challenge of additive manufacturing is the lack of geometric accuracy of the parts. Part geometry measurements generated using Next Engine 3D scanners yields an extremely large amounts of data. The generated data is so large, that it is difficult to characterize and quantify the geometric accuracy of the part directly. Self-Organizing Map is utilized to investigate the major types of geometric deviations.

null

['Zheng, Yong', 'Choi, Sangeun', 'Mathewson, Brian', 'Newman, Wyatt']

2018-11-14T18:06:37Z

1996

Mechanical Engineering

doi:10.15781/T2Z31P79X

http://hdl.handle.net/2152/70256

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SFF', 'CAM-LEM', 'CAD']

Progress in Computer-Aided Manufacturing of Laminated Engineering Materials Utilizing Thick, Tangent-Cut Layers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/27dea143-ff71-4ee8-94fc-5d5c4f21bd3e/download

null

This paper presents recent progress in extending the CAM-LEM process to 5-axis laser cutting for fabrication of laminated engineering components directly from sheet materials. The present extensions enable construction of layered objects from thicker layers by cutting all layers with shaped edges. Use of thicker material layers offers the opportunity for faster build rates and/or improved surface finish. We describe our system and present initial experimental results in utilizing tangent-cut layers for object fabrication. Utilizing surface-tangent information introduces new computational complexities in converting CAD descriptions into machine process control commands. We present an algorithm for achieving this conversion, and we illustrate its successful performance.

null

['Sachs, Emanuel', 'Allen, Samuel', 'Guo, Honglin', 'Banos, Javier', 'Cima, Michael', 'Serdy, James', 'Brancazio, David']

2018-11-28T21:23:35Z

1997

Mechanical Engineering

doi:10.15781/T29P2WR9G

http://hdl.handle.net/2152/70331

eng

1997 International Solid Freeform Fabrication Symposium

Open

['Harder tooling', 'Improvements in surface finish']

Progress on Tooling by 3D Printing; Conformal Cooling, Dimensional Control, Surface Finish and Hardness

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b04bccc9-18d1-4c42-aab0-e5c7538123cd/download

null

Three Dimensional Printing is being applied to the direct fabrication of tooling using metal powders. This paper presents progress updates in four areas: i) thermal management using conformal cooling and related work on enhanced heat transfer using surface textures, ii) data on dimensional control, iii) ) improvements in surface finish, and iv) harder tooling. Conformal cooling has demonstrated significantly improved performance in a production part geometry with simultaneous gains in production rate and part quality obtained as measured against conventional tooling. Surface textures printed on cooling channels have demonstrated 8X enhancement of heat transfer over smooth channels. A set of 18 tooling inserts was fabricated using hardenable stainless steel powder with a resultant tooling hardness of 25-30 Rockwell C. Harder alloy systems are being designed with the aid of computational thermodynamic tools which allow accurate prediction of the interaction of powder and binder. Significant improvements in surface finish were obtained using improved printing technology. Dimensional control of tools conformed well to the expected result of being dominated by control of shrinkage and being predictable to within ±.25%.

null

['Dutta, Deba', 'Kikuchi, Noboru', 'Papalambros, Panos', 'Prinz, Fritz B.', 'Weiss, Lee']

2018-04-19T16:04:20Z

1992

Mechanical Engineering

doi:10.15781/T23R0Q985

http://hdl.handle.net/2152/64377

eng

1992 International Solid Freeform Fabrication Symposium

Open

['Department of Mechanical Engineering & Applied Mechanics', 'MAXWELL', 'MD']

Project MAXWELL: Towards Rapid Realization of Superior Products

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1226f259-66b5-44fc-b602-2ac8d6477fe5/download

null

We describe a new methodology for the design and manufacture of mechanical components. The methodology is a synergism of a new, mathematically rigorous procedure for the concurrent design of shape and material composition of components, and a new manufacturing process called MD* for their realization. The concurrent design strategy yields information about the global shape of the component and its material composition. The fabrication of such designs with novel microstructural configurations require unconventional manufacturing processes. MD* is a shape deposition process for the free-form fabrication of parts from single or composite materials and is ideally suited for realizing the aforementioned designs. Project MAXWELL, therefore, promotes the use of layered manufacturing beyond prototyping tasks and offers the possibility of their integration into the mainstream product development and fabrication process..

null

['Chartoff, R.P.', 'Schultz, J.W.', 'Bhatt, J.', 'Ullett, J.S.']

2019-03-01T17:43:31Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73521', 'http://dx.doi.org/10.26153/tsw/671']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['resins', 'molecular structure']

Properties of a High Temperature Liquid Crystal Stereolithography Resin

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ddbfa131-2504-48ca-bd8f-8f3239bb6578/download

null

A liquid crystal monomer has been developed that contains both acrylate and acetylene reactive groups. The curing behavior and mechanical properties ofthe polymers formed from this monomer have been characterized in this study. Complete cure can be carried out in two separate steps, combining both photo and thermal polymerization. The initial photo- polymerization to form a robust "green" polymer involves crosslinking through the acrylate groups and the subsequent thermal polymerization to increase the crosslink density is accomplished by reaction of the acetylene groups. After the thermal postcure the polymer has an unusually high glass transition, in excess of 300°C. In addition, the monomer exhibits an ordered liquid crystalline (LC) phase. Photopolymerization while in the LC phase locks in the molecular ordering. Mechanical property data and additional information on curing in both the isotropic and LC phases are reviewed in the following presentation.

null