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Optimized Build Plate Design Tool for Metal Laser Powder Bed Additive Manufacturing

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: Develop a software tool capable of optimizing the build plate design for metal powder bed additive manufacturing (AM) systems based on part geometry and features, part location and orientation with respect to the build plate and build direction, as well as the thermal effects inherent in AM. The parts location, orientation, and support structure will be optimized to minimize induced residual stress, control geometric distortion, effectively manage heat dissipation, and mitigate the effort needed in post-process support removal. 

DESCRIPTION: Additive manufacturing (AM) processes are a class of manufacturing techniques which build components from the ground up by selectively adding material in layers rather than removing or deforming bulk material. This allows for increased flexibility in part design, but also introduces additional challenges in terms of build planning. Due to the layer-wise character of AM processes, portions of the final part may not be self-supporting during the manufacturing process given the parts features and orientation. In such cases, supporting structures must be printed only to be removed in an additional manufacturing step to achieve design geometry. Additionally, the significant thermal effects inherent in AM can lead to distortion and cracking as a result of high residual stresses if the parts orientation and location on the build plate are not carefully considered. Current techniques for generating support structure rely on iterating predefined support topologies, such as hexagonal honey combs, which are defined by the designer or selected by the AM machine when the toolpath is generated. This approach is primarily focused on minimizing the size and amount of support structure used. Part location and orientation are typically selected based on operator judgment and experience, or are overlooked entirely. Inadequate build plate design may result in failures during manufacture or final parts that do not meet geometric requirements, increasing time and costs as parts must be rebuilt. To address these issues, a robust build plate design optimization tool is sought. This tool should take into consideration a parts geometry and features, its location and orientation with respect to the build plate as well as the build path, and the characteristic thermal effects of the AM process that drive the formation of residual stresses and lead to unwanted distortion. The optimization tool should be able to provide the instructions necessary for the layout and orientation of parts on a build plate as well as the design and placement of support structure to minimize induced residual stress, control geometric distortion, effectively manage heat dissipation, and mitigate the effort needed in post-process support removal. 

PHASE I: Demonstrate feasibility of a build plate design optimization tool by providing a sample build plate layout and support design for a complex geometry (e.g. overhangs, internal features, thin walls, holes/cylinders, etc.) and compare to the default or traditional build plate layout and support structure design in terms of induced residual stress, distortion, and removal difficulty using a single AM system. 

PHASE II: Develop a prototype of the tool using the framework developed in Phase I optimizing the build plate design to minimize induced residual stress, control geometric distortion, effectively manage heat dissipation, and mitigate the effort needed in post-process support removal. Demonstrate that the optimized build plate layout and support structure design successfully minimized induced residual stress, part deformation, and necessary support structure as well as improved the retention of critical part features for one or more Navy-selected parts using multiple, different AM systems (i.e. different manufacturers.) 

PHASE III: Fully develop the optimized build plate layout and support structure design tool and demonstrate it in a scenario representative of Navy implementation (i.e. using similar equipment, skillsets, and selected part(s) that would be available in a Navy application.) Transition the optimization tool into a stand-alone and/or combined product for use in Navy and commercial additive manufacturing applications. The software tool developed through this effort will improve the quality of additively manufactured parts as well as increase the efficiency of the AM process by reducing errors and failures resulting from poor build plate design and support strategies. As these aspects are valuable to all types of AM, this toolset will be directly applicable to wide range of commercial applications. The proposed build plate optimization toolset would provide industry with an effective means of improving part quality during the build process. Private Sector Commercial Potential: The software tool developed through this effort will improve the quality of additively manufactured parts as well as increase the efficiency of the AM process by reducing errors and failures resulting from poor build plate design and support strategies. As these aspects are valuable to all types of AM, this toolset will be directly applicable to wide range of commercial applications. The proposed build plate optimization toolset would provide industry with an effective means of improving part quality during the build process. 

REFERENCES: 

1: K. Mumtaz, P. Vora, N. Hopkinson (2011). A Method to Eliminate Anchors/Supports from Directly Laser Melted Metal Powder Bed Processes. Retrieved from http://sffsymposium.engr.utexas.edu/Manuscripts/2011/2011-05-Mumtaz.pdf

2: T.A. Krol, E.F. Zaeh, C. Seidel (2012). Optimization of Supports in Metal-Based Additive Manufacturing by Means of Finite Element Models. Retrieved from https://www.researchgate.net/publication/288148661_Optimization_of_supports_in_metal-based_additive_manufacturing_by_means_of_finite_element_models

3: M. Cloots, A.B. Spierings, K. Wegener (2013). Assessing New Support Minimizing Strategies for the Additive Manufacturing Technology SLM. Retrieved from https://www.researchgate.net/publication/289299663_Assessing_new_support_minimizing_strategies_for_the_additive_manufacturing_technology_SLM

4: G. Strano, L. Hao, R.M. Everson, K.E. Evans (2013). A New Approach to the Design and Optimisation of Support Structures in Additive Manufacturing. Retrieved from http://link.springer.com/article/10.1007/s00170-012-4403-x?no-access=true

5: N. Gardan (2014). Knowledge Management for Topological Optimization Integration in Additive Manufacturing. International Journal of Manufacturing Engineering. Retrieved from http://dx.doi.org/10.1155/2014/356256

 

KEYWORDS: Cost Reduction; Metal Additive Manufacturing; Part Quality; Support Structure; Residual Stress Mitigation; Build Plate Design 

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