Browsing by Subject "process parameters"
Now showing 1 - 20 of 34
- Results Per Page
- Sort Options
Item Areal Surface Characterization of Laser Sintered Parts for Various Process Parameters(University of Texas at Austin, 2017) Delfs, P.; Schmid, H.-J.Laser sintered polymer parts consist of rough surfaces due to the layered manufacturing and adherence of incomplete molten particles. The absolute roughness depend on various process parameters like build angle, spatial position, build temperature, exposure order and layer time. Analyses with the help of several areal roughness values of DIN EN ISO 25178-2 considering these parameters are introduced in this paper. Multiple build jobs with 120 µm layer thickness and PA2200 powder were built on an EOS P396 machine using the same build job design with varying process parameters. An individual sample part was designed to receive lots of surface topography information with optical 3D measurements. The results show roughness dependencies for 0° to 180° build angles in 15° steps and eleven distributed in-plane and three axial direction positions depending on different build temperatures, reversed exposure order and layer times. Limitations of the varied parameters are finally derived for the manufacturing of improved surface qualities.Item Automatic Generation of Strong, Light, Multi-Functional Structures from FEA Output(University of Texas at Austin, 2010) Cook, D.; Knier, B.; Gervasi, V.; Stahl, D.An automated process is being developed that will generate a minimal-mass lattice structure that is fabrication-ready for a selected solid-freeform-fabrication (SFF) process. The results of a standard, structural, finite-element analysis (FEA) are processed to define the selection, alignment and sizing of unit lattice elements, such that a minimal-mass structure can be defined. This process will allow for considerations of structural performance (e.g. safety factor), multiple loads, as well as process parameters (e.g. materials and min./max. sizes). Further development would lead to the definitions of composites and multi-functionality, as well as high-performance-computing (HPC) capabilities.Item Bayesian Process Optimization for Additively Manufactured Nitinol(University of Texas at Austin, 2021) Ye, Jiafeng; Yasin, Mohammad Salman; Muhammad, Muztahid; Liu, Jia; Vinel, Aleksandr; Slvia, Daniel; Shamsaei, Nima; Shao, ShuaiAdditively manufactured nitinol enables the design and rapid prototyping of the shape memory alloy with great flexibility and cost-effectiveness in various applications. To achieve high-density fabrication of nitinol, we utilize a Gaussian process-based Bayesian optimization method to efficiently optimize process parameters of the laser beam-powder bed fusion (LB-PBF) process in this work. Specifically, Gaussian process regression is applied to formulate a surrogate model between the critical process parameters (i.e., laser power, scanning speed) and the residual porosity of the nitinol samples. Then Bayesian optimization is integrated to successively explore the design space to search for the optimal process parameters. These two methods are integrated to find the global optimum iteratively. Compared with the traditional trial-and-error methods, the proposed method can quickly find the optimal process parameter for the high-quality nitinol samples, especially with many process parameters, and accelerate the innovations with nitinol in additive manufacturing.Item Characterization of Bulk to Thin Wall Mechanical Response Transition in Powder Bed AM(University of Texas at Austin, 2015) Brown, Ben; Everhart, Wes; Dinardo, JoeIn the development of powder bed AM process parameters, the characterization of mechanical properties is generally performed through relatively large mechanical test samples that represent a bulk response. This provides an accurate representation of mechanical properties for equivalently sized or larger parts. However as feature size is reduced, mechanical properties transition from a standard bulk response to a thin wall response where lower power border scans and surface roughness have a larger effect. This study identifies this threshold between bulk and thin wall for 304L SS on the Selective Laser Melting (SLM) platform and Ti-6Al-4V on the Electron Beam Melting (EBM) platform. A possible method for improving those properties and shifting the transition from bulk to thin wall response to smaller wall thicknesses was investigated. Mechanical testing and fractography was performed on samples to characterize the effect of wall thickness.Item Defect Morphology in Ti-6Al-4V Parts Fabricated by Selective Laser Melting and Electron Beam Melting(University of Texas at Austin, 2013-08-16) Gong, Haijun; Rafi, Khalid; Karthik, N.V.; Starr, Thomas; Stucker, BrentIn order to investigate the morphology of defects present in Selective Laser Melting (SLM) and Electron Beam Melting (EBM) processes, Ti-6Al-4V specimens were fabricated with varying porosity using non-optimum processing parameters. Defective specimens were sectioned and polished for microscopy. Image processing was adopted for statistically analyzing the characteristics of defects, such as distribution of defect area and dimensional proportion of each defect. It is found that defect morphology is influenced by process parameters as a result of a variation in the melt pool. Image processing of a cross-section could be a feasible way for calculating porosity of specimens.Item Design of an Empirical Process Model and Algorithm for the Tungsten Inert Gas Wire+Arc Additive Manufacture of Ti-6Al-4V Components(University of Texas at Austin, 2013) Martina, Filomeno; Williams, Stewart W.; Colegrove, PaulIn the wire+arc additive manufacture process parameters can be varied to achieve a wide range of deposit widths, as well as layer heights. Pulsed Tungsten Inert Gas was chosen as the deposition process. A working envelope was developed, which ensures unfeasible parameters combinations are excluded from the algorithm. Thanks to an extensive use of a statistically designed experiment, it was possible to produce process equations through linear regression, for both wall width and layer height. These equations are extremely useful for automating the process and reducing the buy-to-fly ratio. For a given layer height process parameters can be selected to achieve the required layer width while maximising productivity.Item Development of a Method to Derive Design Guidelines for Production-suitable Support Structures in Metal Laser Powder Bed Fusion(University of Texas at Austin, 2021) Lammers, S.; Lieneke, T.; Zimmer, D.Solid support structures in metal laser powder bed fusion have a significant influence on the economic applicability, component quality and process stability and represent a central challenge for widespread industrial use. As the connection of the components to the building platform by supports is essential, the negative effects must be minimized at the same time as the supporting effect is optimized. Within the scope of this study, a standardized method is developed that allows the investigation of several support structures and parameters with regard to their influence on the target variables: component quality, process efficiency and stability. In addition to the proof of general suitability, the applicability is investigated using so-called standard elements. Based on the experimental results, design guidelines are derived, which will serve as a basis for decision-making during the selection of support structure for an individual application.Item Effect of Process Parameters and Heat Treatment on the Microstructure and Mechanical Properties of SLM-built HY100 Steel(University of Texas at Austin, 2014) Dilip, J.J.S.; Stucker, Brent; Starr, Thomas L.HY100 is a high strength low alloy steel used for naval and pressure vessel applications. In general, the alloy is used in the quenched and tempered condition. In the present work, fully dense metallic samples were produced from HY100 pre-alloyed powders using selective laser melting (SLM). Test samples were built with varying process parameters (scan speed and laser power). The SLM-built samples were given direct tempering treatment and a standard quench and temper heat treatment. Tensile properties of the samples were evaluated in direct temper, and quench and temper conditions. The study investigates the influence of process parameters and heat treatment on the microstructure and mechanical properties of SLM-built HY100 steel.Item The Effect of Process Parameters and Mechanical Properties of Direct Energy Deposited Stainless Steel 316(University of Texas at Austin, 2017) Izadi, Mojtaba; Farzaneh, Aidin; Gibson, Ian; Rolfe, BernardProcess parameters in Direct Energy Deposition (DED) Additive Manufacturing are playing an important role in order to fabricate desired parts. In this research, we studied the effect of 3 process parameters, namely laser power, scan speed and powder feed rate. Based on variation of these parameters, we examined macrostructure and mechanical properties of stainless steel 316 fabricated parts, employing an orthogonal L9 array using the Taguchi technique. The results showed laser power to be the most effective factor whereas scan speed and powder feed rate were respectively less effective. In addition, effect of height of deposition was also considered. The results indicated change in macrostructure with increasing height. Finally, validation of a previously defined energy density equation for the DED process was studied. The results clearly showed the current energy density equation cannot fully represent a relation between input energy and output geometry, macrostructure, and mechanical properties.Item Effect of Process Parameters on Selective Laser Melting Al2O3-Al Cermet Material(University of Texas at Austin, 2019) Liao, Hailong; Zhu, Haihong; Zhu, Junjie; Chang, Shijie; Zeng, XiaoyunThe cermet composite material is one of the researches focuses in the field of materials, for it can combine the toughness of metal and the hardness of ceramics. In this work, Al2O3-Al cermet composite with a mass ratio of 1:1 was fabricated by selective laser melting process. The effect of process parameters on the relative density and Al2O3 loss rate, as well as the Al2O3 loss mechanism, was investigated in detail. The results show that Al2O3 undergoes melt recrystallization and is significantly aggregated. The aggregated Al2O3 exhibits a network distribution in the metal matrix. The process parameters have a great influence on the relative density and the Al2O3 loss rate. As the scanning speed decreases, the relative density and the Al2O3 loss rate are changed with a contrary tendency. The loss mechanism is that the aluminum acts as a reducing agent, causing the Al2O3 becoming a gaseous substance Al2O during selective laser melting process.Item Effects of Process Parameters and Heat Treatment on the Microstructure and Mechanical Properties of Selective Laser Melted Inconel 718(University of Texas at Austin, 2018) Huang, Wenpu; Wang, Zemin; Yang, Jingjing; Yang, Huihui; Zeng, XiaoyanIn this study, Inconel 718 superalloy was fabricated by selective laser melting (SLM) and solution treated at 980-1230 ℃subsequently. The process window was firstly set up based on the density of the samples. Samples were fabricated using various parameters within the process window to investigate the effects of process parameters on microstructure and mechanical properties. The average dendrite arm spacing and the volume fraction of Laves phase raise along with the increasing energy input. However, no distinct difference of tensile properties was found under parameters in the process window. Interdendritic Laves phase decreases with the solution temperature, while the grain size has the opposite trend. Finally, the solution temperature was fixed at 1080 ℃to dissolve Laves phases and obtain fine grains. After solution + aging heat treatment, the tensile strengths and ductility all exceed the wrought Inconel 718.Item Effects of Stripe Width on the Porosity and Mechanical Performance of Additively Manufactured Ti-6Al-4V Parts(University of Texas at Austin, 2021) Soltani-Tehrani, Arash; Yasin, Mohammad Salman; Shao, Shuai; Shamsaei, NimaIn laser powder bed fusion (L-PBF) additive manufacturing, parts are manufactured in a layer-by-layer pattern. In each layer, cross-sections can be scanned with or without partitioning by the laser, which are commonly known as “stripe” and “meander” patterns, respectively. Under the two scanning strategies, the thermal history experienced by the part can be considerably different. Accordingly, defect distribution, microstructure, and mechanical properties may be affected. In this study, two sets of Ti-6Al-4V specimens were fabricated using L-PBF: in one set, the tracks were partitioned in 5-mm stripes, while in the other set, they were partitioned at 100 mm resulting in no stripe seams in the cross-section. It was found that altering the stripe width can considerably affect the laser penetration depth, the defect content, and consequently fatigue performance. However, tensile strength was not much sensitive to changing the stripe width.Item Efficient Sampling for Design Optimization of an SLS Product(University of Texas at Austin, 2017) Xu, Nancy; Tutum, Cem C.In this work an efficient constrained surrogate-based sampling algorithm is implemented to optimize Selective Laser Sintering (SLS) process parameters for maximizing the tensile strength of a tensile specimen. Two variations of the algorithm have been implemented and tested on a Farsoon HT251P machine using (polyamid) PA3300 polymer powder. The algorithm is based on building a statistical predictive model of the objective response (i.e., maximization of tensile strength), aggregating the constraint function (i.e., limited amount of warping), in an iterative manner by simultaneously improving the accuracy of the predictive model as well as searching for the optimum set of process parameters. The difference in two algorithmic variations is the number of samples to update at each iteration. While the first method is based on a single sample update, the latter searches for multiple simultaneous updates to let the manufacturer try several potentially good sets of parameters in the same machine to eventually speed up the experimental evaluation procedure.Item Examination of the LPBF Process by Means of Thermal Imaging for the Development of a Geometric-Specific Process Control(University of Texas at Austin, 2019) Pichler, T.; Schleifenbaum, J.H.The development of process parameters for the Laser Powder Bed Fusion (LPBF) process is typically carried out by the manufacturing and metallurgical analysis of geometrically primitive test specimens (e.g. cubes). The process parameters identified in this way are used for the manufacturing of parts which are characterized by a high geometric complexity and a combination of solid and filigree component areas. Due to the discrepancy between the parameter development on primitive specimens and applications with complex parts, a geometric-specific process control is to be developed. In the context of this work different sample geometries are manufactured from Ti6Al4V by LPBF and the process is monitored by thermal imaging. The influence between component geometry and process parameters on the thermal behavior is shown.Item Exploring Variability in Shape Memory Properties of Stereolithography Printed Parts(University of Texas at Austin, 2016) Choong, Y.Y.C.; Saeed, M.; Eng, H.; Su, P.-C.; Wei, J.Shape memory polymers (SMPs) are smart materials that can change shape and revert to their permanent shape upon external stimulus. Most fabrications of SMPs are based on conventional methods which limit design freedom, hence additive manufacturing presents an alternative to expanding more possibilities for applications. In this study, curing process parameters were optimized for printing of photopolymerized thermoset SMPs by the stereolithography process. Tert-butyl acrylate (tBA) and di (ethylene glycol) diacrylate (DEGDA) were copolymerized with variations in crosslinkers to create networks with well-separated transition temperatures (Tg) that varied in a range from 43.6 to 74.1°C. A fold-deployable shape memory test was performed and revealed that free-strain recovery and retention deteriorate with increasing Tg. Nevertheless, the SMPs can undergo at least 20 repeated fold-deploy cycles before failure. These results are intended to provide better understandings in processing SMPs via stereolithography, while exploring variability in Tg widens the range of possible applications.Item Further Study of the Electropolishing of Ti6Al4V Parts Made via Electron Beam Melting(University of Texas at Austin, 2015) Yang, Li; Lassell, Austin; Perez Vilhena Paiva, GustavoIn this study, the effect of various parameters including the voltage, current, polishing time, temperature and electrode spacing on the electropolishing quality of Ti6Al4V samples made via electron beam melting was investigated using specialty designed research setups. The relationships between these process parameters and the surface roughness of the parts were established experimentally.Item High Viscosity Jetting System for 3D Reactive Inkjet Printing(University of Texas at Austin, 2013) Yang, H.; He, Y.; Tuck, C.; Wildman, R.; Ashcroft, I.; Dickens, P.; Hague, R.High viscosity ink is a potential solution for the improvement of current 3D ink jetting technology. In this study, experiments are carried out to study a series of inks with differing viscosities jetted with PicoDot™ jet valves under different process parameters of temperature and pressure. Results show that a wide range of ink materials from low viscosity (water like materials) to very high viscosity (thixotropic materials) can be jetted with the piezoelectric actuated jet valves without the need of solvents and surfactants. The jetting volume can be controlled under certain conditions between 2nl and 15nl. The jetting performances for low, medium and high viscosity inks have been recorded by high-speed video photography.Item Investigating the Links Between the Process Parameters and Their Influence on the Aesthetic Evaluation of Selective Laser Melted Parts(University of Texas at Austin, 2016) Galimberti, G.; Doubrovski, E.L.; Guagliano, M.; Previtali, B.; Verlinden, J.C.This study is a precursor to gaining a deeper understanding of how each parameter of the Additive Manufacturing (AM) process influences the aesthetic properties of 3D printed products. Little research has been conducted on this specific aspect of AM. Using insights from the work presented in this paper, we intend to develop design support tools to give the designer more control over the printed products in terms of aesthetics. In this initial work, we fabricated samples using Selective Laser Melting (SLM) technology, and investigated the parameters geometry, building strategy, and post-processing. We asked participants to evaluate the visual and physical interaction with the manufactured samples. Results show that, in addition to geometry and post-processing, the aesthetic evaluation can also be strongly influenced by the SLM process’ building strategy. This understanding will enable us to develop tools to give designers more control over the part’s aesthetic appearance. In addition, we present a systematic procedure and setup to evaluate the aesthetic appearance of products manufactured using AM.Item Investigation of the influence of process parameters on productivity in the LPBF process for the material Inconel 718(2023) Bodger, C.; Gnaase, S.; Lehnert, D.; Troster, T.The nickel-based alloy Inconel 718, which is used in aerospace technology, poses a great challenge to conventional machining due to its high strain hardening and toughness. Here, the laser powder bed fusion process (LPBF) offers an alternative with potential savings if sufficiently high productivity can be achieved. Based on the parameter study carried out, starting from the SLM Solutions standard parameters for the manufacturing of components, exposure parameters could be developed to realize manufacturing with 120 μm and 150 μm layer thickness, with almost the same geometric accuracy. For this purpose, the process parameters of laser power, focus diameter, hatch distance and scan speed were varied. The negative defocusing of the laser showed a positive effect on the density of the parts, realizing densities ≥ 99.94 %, with high dimensional stability and good mechanical properties. Considering the reduced manufacturing time of up to 61 %, a significant increase in productivity was achieved.Item Investigations for the Optimization of Visual and Geometrical Properties of Arburg Plastic Freeforming Components(University of Texas at Austin, 2021) Hecker, F.; Elsner, C.L.; Hirsch, A.; Moritzer, E.Arburg Plastic Freeforming (APF) is an additive manufacturing process with which three-dimensional, thermoplastic components can be produced layer by layer. Visual and geometrical properties are a major criterion for characterizing the resulting component quality. The aim of this study was to investigate the influences on visual and geometrical properties of APF components depending on process parameters. Initially the focus was on the analysis of the shrinkage behavior of ABS-M30 (Stratasys). On the basis of the results and an existing procedure by the machine manufacturer, an optimized procedure for determining the scaling factors was developed to counteract the shrinkage. With this procedure a higher dimensional accuracy of the components can be achieved. In addition, it was investigated whether an adaption of the form factor based on a mathematical model depending on the component geometry makes sense. The results were transferred into manufacturing guidelines, which allow the user of the APF-technology to optimize process parameters more efficiently.