Browsing by Subject "SLS"
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Item An Adaptive Control Architecture for Freeform Fabrication(1996) Boudreaux, J.C.Item Advanced technology innovation mapping tool to support technology commercialization(2013-12) Felkl, Jakub, 1982-; Nichols, Steven Parks, 1950-This work outlines an Innovation Gap in technology commercialization and presents a novel tool, the Advanced Technology Innovation Mapping (ATIM) tool to address this gap. The tool aims to support technology commercialization in early stages of & prior to the New Product Development Process. The dissertation includes a detailed rationale, description, history, similar and originating methods for this tool based on Value Engineering and Function Maps for Design. This work also demonstrates on several example studies the use of the tool and evaluates via an exploratory study the usefulness of the tool. Research tests the tool in educational and training programs at the University of Texas at Austin and finds that the tool improves user understating of majority of important factors for technology commercialization (customer, technology, development activities). User feedback supports these conclusions. In the future the tool could be further expanded, more standardized and improved. Additionally, the work proposes further ways to study the tool in different settings and with groups of different sizes beyond this early exploratory study.Item The Application of an Artificial Body Force to the Selective Laser Sintering Process(1992) Melvin, Lawrence S. III; Beaman, J.J.An artificial body force generated by a magnetic field is applied to the green powder bed of a ferromagnetic powder during the Selective Laser Sintering process. Preliminary experiments and theory are formed to determine whether the artificial body force is beneficial to the Selective Laser Sintering process and if it is usable within that process. Several applications are discussed including microgravity situations and two phase sintering processes. It is determined that the magnetic body force is beneficial to the Selective Laser Sintering process.Item Application of Factorial Design in Selective Laser Sintering(1992) Deng, Xioaming; Beaman, Joseph J.Selective Laser Sintering (SLS) is a complex process involving many process parameters. These parameters are not all independent. A factorial design technique is utilized to study the effects of three main process parameters, laser power, laser beam scanning speed, and powder packing density as well as their interactions on the sintering depth and fractional density. The results of this investigation provide useful information for the further experimental analysis of the process parameters and for selecting suitable parameters for SLS process.Item Benchmarking of Rapid Prototyping Systems - Beginning to Set Standards(1994) Jayaram, Dureen; Bagchi, Amit; Jara-Almonte, C.C.; Oreilly, SeanMany rapid prototyping (RP) technologies are available today and more are being developed around the world. The absence of benchmarking standards in the RP industry has led manufacturers to use their own standards and make claims about superior performance. The need for testing standards is already felt; standardization will become imperative in the near future. The present work aims to lay the groundwork for the development of standards to measure various performance factors. Issues such as appearance and finish are studied qualitatively; the test part and some findings are presented. Issues such as repeatability, warpage, curl, creep, shrinkage and tensile strength are proposed to be studied quantitatively; test parts designed for studying these are described. Benchmarking standards will help users choose proper systems for their applications and help operators in monitoring machine performance, enabling better control over part building.Item Binder Development for Indirect SLS of Non Metallics(University of Texas at Austin, 2010) Chakravarthy, Kumaran M.; Bourell, David L.In this work, a binder system for non metallics such as graphite has been developed and tested. A graphite-phenolic mixture was used for making bipolar plates using SLS. Phenolic resin melts (~90°C) instead of cross-linking (~165°C) in the SLS machine. During post processing in a furnace, the SLS parts slumped due to remelting of phenolic resin with no other binder present to hold the powder together. To prevent this slumping and to increase the green strength of the SLS parts, a new binder system was developed with Nylon/11 added. Nylon/11 has a melting point of ~185°C and is able to hold the SLS part together until the phenolic can cross link, preventing slumping. Single layer scan experiments with different compositions and SLS parameters were run to identify optimum composition and SLS parameters. Three point bend specimens were prepared with 70 wt. % Graphite-25 wt. % Phenolic- 5 wt. % Nylon/11 and 70 wt. % Graphite-20 wt. % Phenolic- 10 wt. % Nylon/11, tested and compared to graphite-phenolic parts. No significant increase in green strength was attained with Nylon/11 addition.Item Biocompatibility of SLS-Formed Calcium Phosphate Implants(1996) Lee, G.; Barlow, J.W.; Fox, W.C.; Aufdermorte, T.B.A method for fabricating artificial calcium phosphate bone implants by the Selective Laser Sintering (SLS) process has been developed that can fabricate complex and delicate calcium phosphate bone facsimiles from a variety of data inputs including Computed Tomography(CT) files (1). This paper discusses two in vivo biocompatibility studies of SLS-formed calcium phosphate implants in both rabbits and dogs. Histologic analysis shows a high degree of biocompatibility and bone ingrowth in both studies.Item Ceramic Structures by Selective Laser Sintering of Microencapsulated, Finely Divided Ceramic Materials(1992) Vail, N.K.; Barlow, J.W.The feasibility of producing ceramic green parts by Selective Laser Sintering from microencapsulated, finely divide ceramic powders has been reported in an earlier paper. Post-processing of a silica/zirconium orthosilicate system and an alumina system, both utilizing a polymer binder in the form of a coating, are discussed in this paper. Ceramic green parts require postprocessing to remove the intermediate polymer binder and to impart strength properties to the ceramic bodies. In this paper, the use of ceramic cements and high temperature firing to realize strengths will be discussed. The effects of cement concentration and controlled drying rates on the strengths and dimensional accuracy of the ceramic bodies are also discussed.Item Characterization of quartz lamp emitters for high temperature polymer selective laser sintering (SLS) applications(2013-12) Kubiak, Steven Thomas; Beaman, Joseph J.This thesis provides investigation into the interaction between quartz lamp emitters and polyether ether ketone (PEEK) powder. Calculations and experiments concerning the conductivity and emissivity of the powder at various temperatures are performed. The thermal profile of the emitter on a flat powder bed is captured using thermal imaging. The effect of exposing a pile of powder to the emitter and the subsequent thermal gradient through the pile is measured and analyzed. Based on these results, ramifications for the application of these emitters to selective laser sintering (SLS) machines for processing high temperature polymers such as PEEK are discussed.Item A compilation of design principles and guidelines for selective laser sintering(2016-05) Pradhan, Nivedita; Seepersad, Carolyn; Crawford, Richard HThe term Additive Manufacturing (AM) is used to describe several manufacturing technologies that share the same basic principle of producing parts directly from their CAD models without the need for special tooling, by adding material selectively one layer at a time. Current research focuses on one such technology called Selective Laser Sintering (SLS) where thin layers of powdered thermoplastic material are fused using a laser beam. With no part-specific tooling required, the product development cycle is drastically shortened. This lack of tooling, coupled with freedom of placement of material, opens the door to several design opportunities unique to AM such as increased geometrical design freedom and the ability to manufacture low production volumes economically. Gradual improvements in process accuracy and selection of materials over time have resulted in a shift in application of AM from rapid prototyping to direct manufacturing and even ‘democratization’ of the product development process in which even non-professional users can rapidly manufacture products as long as there is a CAD model for the part. However, the move to direct manufacturing of end-use parts also means that part quality in terms of conformance to product specification becomes important for the product to successfully perform its function. The research in this thesis is focused on documenting these manufacturability capabilities and limitations for Selective Laser Sintering. It focuses specifically on thermoplastics, especially Nylon 12 polyamide materials known by the trade names PA 2200 and Duraform PA. While several design resources have been created based on industry best practices developed through experience, they are scattered throughout the literature and are not readily available to designers. It is also difficult to compare and draw quantitative inferences from existing guidelines as they are developed independently under dissimilar process conditions. Therefore, a prime focus of this research is to synthesize and compile existing guidelines into a comprehensive document. The first objective of this research is to compile a user-friendly resource, in the form of design principles and guidelines, to help designers make early process selection decisions, optimize part quality and minimize manufacturing cost. A systematic literature review of available guidelines, exploratory studies and case studies is conducted to develop actionable design recommendations that are within the scope of the designer. The second objective of this research is to address the lack of adequate process tolerance information that can reliably predict the quality of parts produced by the selective laser sintering process. This information is important to accurately evaluate the process during early process selection. A test part is proposed to measure dimensional deviations for various features (such as holes, gaps, cylinders, walls, clearances, etc.) across a range of dimensions and along different orientations. Finally, a sampling plan that represents sources of variability in the process is put forward to collect statistical data in an economical manner.Item Cost model for commercially-available additive manufacturing machines(2021-05-11) Martin Cardenas, Oscar A.; Seepersad, CarolynCost models for individual commercial processes have been developed for additive manufacturing machines in the past; however, software and detailed information about the machines for cost modeling tend to be privatized within the industry. The addition of the Center for Additive Manufacturing and Design Innovation to The Walker Department of Mechanical Engineering at The University of Texas at Austin expanded the additive manufacturing facility to include the EOS M280 DMLS, 3D Systems HiS/HiQ Vanguard SLS, 3D Systems SLA 5000, and the Stratasys J750 Digital Anatomy Printer additive machines. To provide quotes for parts and obtain build-specific information for the aforementioned processes, an open-source software program is developed along with the cost models for each individual process to speed up the required calculations and provide an interface for the operator of the center to experiment with different build parameters. The design of each cost model for all four additive manufacturing processes explores assumptions that define the variables used by the open-source software program to perform calculations. The software program includes an interface for the operator to input part and build parameters to obtain desired outputs. Additionally, the software program includes underlying spreadsheets for the operator to make future edits and keep track of quotes. As part of the cost model for the DMLS, SLS, and SLA machines, a part build time estimation experiment is developed to aid the accuracy of machine related cost calculations. Experimental parts are designed and created to record data and develop an equation for the total build time of a desired part for a given process. The results of this experiment are verified with known machine-generated data to validate the accuracy of the results. Additionally, a case study is performed with an experimental build to verify the results of the cost models when compared to Stratasys’ web quoting tool to validate the behavior of the total cost per part estimation for a given process. Due to implications related to the COVID-19 pandemic and the 2021 Texas snowstorm, delays limited the data gathering from the center. Therefore, future adjustments to experimental data are discussed to further improve the cost model’s accuracy. Furthermore, as more knowledge of these processes is gathered by the center over time, adjustment to values in the cost model will be necessaryItem Densification Behavior of SLS Processed Al2O3/Al Composite(1995) Rao, T. Srinvasa; Bourell, D.L.; Marcus, H.L.Production of structurally sound parts by any rapid prototype technique is essential, because fully functional features are necessary where application testing is required. In the present work, a powder blend of A1203/AI (3:1 by weight) was mixed with ammonium dihydrogen phosphate and subjected to selective laser sintering (SLS) using a C02 laser. An attempt has been made to increase the powder bed density by introducing vibration to the part cylinder. These SLS processed preforms were then subj ected to a secondary heat treatment in a hydrogen atmosphere and to hot isostatic pressing. Densification behavior of these Al20 3/Al composite preforms is discussed.Item Design of a High Temperature Workstation for the Selective Laser Sintering Process(1991) Das, Suman; McWilliam, John; Wu, Benny; Beaman, J.J.Item Development of a Selective Laser Reaction Sintering Workstation(1992) Birmingham, B.R.; Tompkins, J.V.; Zong, G.; Marcus, H.L.The purpose of this paper is to describe the design and operation of a Selective Laser Reaction Sintering workstation developed at The University of Texas. The workstation allows the study of solid freeform fabrication of reaction sintered materials on a research scale. The mechanical and control systems of the workstation are detailed, and Selective Laser Reaction Sintering as a technique is discussed including example material systems that are currently under study.Item The Development of a SLS Composite Material(1995) Forderhase, Paul; McAlea, Kevin; Booth, RichardThe development of a commercial SLS nylon-based composite material (LNC 7000) is described. Nylon composite candidate systems with different volume fractions of a number of glass fiber and glass bead reinforcements were screened. It was found that fully dense SLS parts with excellent mechanical properties could be made from a number of reinforced nylon materials. An optimized material containing 29 volume percent 35 Ilm diameter glass beads was selected based on the processing behavior and mechanical properties of the candidate systems. The performance of this optimized material is described. In addition, complementary aspects of the composite nylon and unreinforced nylon materials (LN 4010 and LNF 5000) are discussed.Item Development of Nanocomposites for Solid Freeform Fabrication(1993) Manthiram, A.; Chi, F.; Johnson, F.; Birmingham, B.R.; Marcus, H.L.Nanocomposites in which the constituents are mixed on a nanorneter scale can provide important advantages in the Selective Laser Sintering (SLS) and Selective Laser Reactive Sintering (SLRS) processes. The larger surface area and grain boundaries in the nanocolnposites compared to that in the conventional microcomposites are expected to enhance the solid state diffusion during laser irradiation as well as during any other subsequent processes. Our strategy is to design and develop nanocomposites in which one nanosize cOlnponent has a lower melting point than the other nanosize component, either of which can serve as the matrix phase. The nanoscale dispersion of the low melting component can aid the sintering process during SLS or SLRS. Nanocomposite powders of AI203-COOx, Ab03-NiO, A1203-CO and A1203-Ni have been synthesized by sol-gel processing and are evaluated by SLS.Item Development ofDirect SLS Processing for Production ofCermet Composite Turbine Sealing Components - Part I(1996) Fuesing, T.; Brown, L.; Das, S.; Harlan, N.; Lee, G.; Beaman, J.J.; Bourell, D.L.; Barlow, J.W.; Sargent, K.This paper presents the development to date of SLS (selective laser sintering) technologies for production of cermet composite turbine sealing components, the particular application being an abrasive blade tip. The component chosen for the application is an integral part of the low pressure turbine in a IHP'TET (Integrated High Performance Turbine Engine Technology) demonstrator engine. Both indirect and direct SLS techniques are being developed. Initial trials and process development involved the use of fugitive polymeric binders. Sequential refinements were performed to develop a binderless direct SLS process. Results from mechanical testing indicate that acceptable microstructure and properties are attainable by SLS with substantial cost savings as compared to the currently employed production method. This is the rust instance ofdirect SFF methods applied to a functional componentItem Direct Laser Fabrication of High Performance Metal Components Via SLS/HIP(1999) Wohlert, Martin; Das, Suman; Beaman, Joseph J.; Bourell, David L.Recent research in the area of direct freeform fabrication of components via selective laser sintering/hot isostatic pressing (SLS/HIP) has focused on the processing of Alloy 625. Alloy 625 is a nickel-based superalloy which provides high temperature strength and corrosion resistance. Alloy 625 test specimens were successfully SLS processed with an integral gas impenneable skin or "can". These samples were subsequently HIPed to high density (>99.5%). Characterization of the test specimens indicated that microstructures similar to conventionally processed P/M materials are achieved in the HIP consolidated "core" region ofthe parts, while structures similar to those found in cast materials are present in the SLS processed "can" regions. Mechanical analysis of Alloy 625 SLS/HIP parts and production of complex structures will commence shortly.Item Direct Selective Laser Sintering and Containerless Hot Isostatic Pressing for High Performance Metal Components(1997) Das, Suman; Wohlert, Martin; Beaman, Joseph J.; Bourell, David L.A novel net shape manufacturing method known as SLSIHIP that combines the strengths ofselective laser sintering (SLS) and hot isostatic pressing (HIP) is presented. Direct selective laser sintering is a rapid manufacturing technique that can produce high density metal components of complex geometry with an integral, gas impermeable skin. These components can then be directly post-processed to full density by containerless HIP. The advantages of in-situ HIP encapsulation include elimination of a secondary container material and associated container-powder interaction, reduced pre-processing time, a short HIP cycle and reduction in post-processing steps compared to HIP of canned parts. Results of research conducted on Inconel 625 superalloy, Ti-6AI-4V and Monel are presented. This research is funded by DARPAlONR contract N00014-95-C0139 titled "Low Cost Metal Processing Using SLSIHIP".Item Direct Selective Laser Sintering of High Temperature Materials(1992) Zong, G.; Wu, Y.; Tran, N.; Lee, I.; Bourell, D.L.; Beaman, J.J.; Marcus, H.L.Selective Laser Sintering (SLS) involving a coexisting liquid and particulate solid during the SLS processing can be used to produce freeform parts directly with high temperature materials. Factors such as scanning laser power density, residence time, scan line spacing, the interfacial energies between the liquid and solid phases, powder bed biasing temperature, and sintering atmosphere greatly affect the microstructure evolution in the SLS process. Direct SLS of high melting temperature mixed powder materials was demonstrated using a 1.1 kW C02 laser SLS system. The relationship between the microstructures and the process parameters will be described.