UC Irvine

Laser Engineered Net Shaping, LENS®, is a multi-variable process of Additive Manufacturing that employs a high-power laser to deposit powder feedstock onto a substrate to build parts layer-by-layer. Advantages of this process are tailored microstructures with optimized structural properties for a variety of industry applications. The LENS® system parameters allow for variable user control but also introduce complexity into the process where every change in deposition procedure results in different effects on the build. To understand the connection between process parameters and build quality, each variable should be fully understood. The focus of this study was to isolate single variables and exhaustively analyze the effects on the deposition process. The first project investigates reusing powder feedstock for multiple cycles and the effects on powder properties and build quality. The second project examines the effect of varying the hatch rotation angle parameter by characterizing the resulting microstructural and mechanical properties. Microstructural and compositional characterization was done through several microscopy techniques to analyze the 316L SS powders, used throughout this thesis, and the manufactured parts. Bulk material properties were analyzed with compression, microhardness, and density testing. It was found that reusing powder for ten cycles causes minimal changes to the powder properties. The properties of builds tested from select cycles were unchanged. Varying the hatch rotation angle between layers of a deposition did affect microstructural development which influenced mechanical properties. Finally, the complexity of the LENS® system was discovered through extensive operation, and the care required to manufacture consistent parts is exemplified.