Browsing by Subject "part quality"
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Item Influence of Process Time and Geometry on Part Quality of Low Temperature Laser Sintering(University of Texas at Austin, 2017) Yamauchi, Yuki; Niino, Toshiki; Kigure, TakashiThe authors are developing a novel laser sintering process that prevents parts from warping by anchoring them to a rigid base plate. Since the powder bed temperature of the process is normally lower than in the standard process, the laser is required to supply more energy in the novel process, namely low temperature process. Accordingly, the part quality is more sensitive to laser parameters. Additionally, accumulation and dispersion of energy which is supplied by the laser through layers plays an important role in the consolidation of the powder. Thus, in low temperature process, parameter relating part geometry and time affects the part quality more than in standard high temperature process. In this research, the influence of part size and process time per layer on the density of parts as a primary index of part quality is investigated. Density decreases as the process time per layer increases. With respect to part size, density increases as parts become larger.Item Layer by Layer Validation of Geometrical Accuracy in Additive Manufacturing Processes(University of Texas at Austin, 2013) Zeng, Kai; Patil, Nachiket; Gu, Hengfeng; Gong, Haijun; Pal, DeepankarGeometrical inaccuracy from shrinkage and residual stress-induced deformations are key sources of defects in Additive Manufacturing (AM). In most AM processes the CAD model is represented by an STL file which is sliced into layers. The Common Layer Interface (CLI) and StereoLithography Interface (SLI) files are two layer file formats which store this slice information and can be data mined to analyze sources of error. By comparing the original STL file against a ‘stacked’ model based upon SLI and CLI files, a “theoretical" part accuracy can be created. In addition, these SLI/CLI files can be combined with detailed process parameter knowledge such as scan pattern, laser power, scan speed, etc., to enable a numerical prediction of part accuracy and deformations on a layer-by-layer basis. This paper introduces a research project which is developing software and hardware tools to enable prediction and measurement of part dimensions on a layer-by-layer basis with the goal of real-time part quality validation and closed loop control.Item A Material-Based Quality Concept for Polymer Laser Sintering(University of Texas at Austin, 2013-08-16) Josupeit, Stefan; Rüsenberg, Stefan; Schmid, Hans-JoachimIn this work, the quality of laser sintered parts is investigated along a defined process chain for a nylon 12 material (PA 2200) on an EOSINT P395 laser sintering system. Important influencing factors are figured out. Rheological powder characterization methods are investigated as well as mechanical, physical and other chosen part properties. The concept allows reproducible part quality characteristics and is used to obtain (testing) temperature dependent material data. It can also be extended on further materials based on nylon 12: PA 2241 FR, which is convenient for the aircraft industry due to its flame-retardant properties, and PA 2221, which has economic advantages due to a lower material consumption.Item Simulation of the Laser-Powder Bed Fusion Process for Determining the Effects of Part-to-Substrate Location and Orientation on Distortion in a Connecting Rod(University of Texas at Austin, 2021) Weinhold, Benjamin; Heck, Blake; Albright, Ashton; Wang, Keran; Grote, Jon-Michael; Adeniji, Emmanuel; Masoomi, Mohammad; Thompson, ScottThe use of process simulation for designing parts and ensuring their effective additive manufacture can result in reduced product development times which would otherwise require costly trial-and-error manufacturing and testing experiments. The goal of this project was to determine the effects of part-to-substrate location and part build orientation on final part quality as measured via distortion. A connecting rod from an engine was selected for re-design for mass reduction and additive manufacturing via laser powder bed fusion (L-PBF). The rod was modeled and optimized using the topology optimization features of ANSYS® Workbench. A mass reduction of ~44% was achieved and unique design features were revealed. After topology optimization, the L-PBF process was simulated using the ANSYS Workbench Additive Wizard while having the optimized rod in three separate orientations at two different substrate locations. In all cases investigated, build orientation proved to have a more significant impact on distortion than substrate location. The effect of over supporting the part for distortion control can be investigated further to circumvent location/orientation dependencies.Item System Identification and Feedback Control for Directed-Energy, Metal-Based Additive Manufacturing(University of Texas at Austin, 2015) Seltzer, D.M.; Wang, X.; Nassar, A.R.; Schiano, J.L.; Reutzel, E.W.Additive manufacturing of metal parts is a complex process where many variables determine part quality. In addition to manipulated process variables, such as travel speed, feedstock flow pattern, and energy distribution, other exogenous inputs also determine part quality. For example, changing build geometry and a growing global temperature. In addition, there are random external disturbances such as spatter on a cover lens. Both manipulated process variables and exogenous inputs affect dimensional tolerance, microstructure, and other properties that determine the final part quality. Our long term aim is to improve part quality through real-time regulation of measurable process variables using vision-based feedback control. As a starting point, we present a process model that relates scanning speed and laser power to build height and melt pool width. These results demonstrate the necessity for using multi-input multi-output feedback control techniques and provide information for refining the frame rate and spectral sensitivity of the imaging system.Item Technological Challenges for Automotive Series Production in Laser Beam Melting(University of Texas at Austin, 2017) Haeckel, Felix; Meixlsperger, Maximilian; Burkert, TorstenCompared to traditional production methods, Additive Manufacturing enables a tool free production leading to higher flexibility, freedom of design and lightweight potential. For these reasons the BMW Group is proceeding from the production of prototypes to the direct series production of parts. For metal components, the process of selective Laser Beam Melting is able to realize these potentials. Aside from the economic issues, technological challenges also have to be met. Among them is achieving consistent part quality in the production of same parts. To achieve technical specifications compliant in series production, a defined process stability and reproducibility of the part properties is needed. This reproducibility is investigated for the process of selective Laser Beam Melting. Also variables which have the biggest impact on the part quality throughout a simulated series production are being examined. Thus the reproducibility of the process can be quantified. To guarantee a high and stable part quality in the future, approaches are being developed to monitor or systematically prevent influences, which are found to have a negative effect on the process quality.Item Use of SWIR Imaging to Monitor Layer-to-Layer Part Quality During SLM of 304L Stainless Steel(University of Texas at Austin, 2018) Lough, Cody S.; Wang, Xin; Smith, Christopher C.; Adeniji, Olaseni; Landers, Robert G.; Bristow, Douglas A.; Kinzel, Edward C.This paper evaluates using in-situ SWIR imaging to monitor part quality and identify potential defect locations introduced during Selective Laser Melting (SLM) of 304L stainless steel. The microstructure (porosity, grain size, and phase field) and engineering properties (density, modulus, and yield strength) depend on the thermal history during SLM manufacturing. Tensile test specimens have been built with a Renishaw AM250 using varied processing conditions to generate different thermal histories. SWIR imaging data is processed layer-to-layer to extract features in the thermal history for each process condition. The features in the thermal history are correlated with resulting part engineering properties, microstructure, and defects. The use of SWIR imaging is then discussed as a potential for processes monitoring to ensure part quality and develop layer-to-layer control in SLM.