Design and fabrication of an open-architecture selective laser melting system

Abstract

Additive manufacturing (AM) is a rapidly advancing manufacturing paradigm that involves selective placement of material, layer-by-layer, as determined by a three-dimensional digital model. AM allows for freeform geometries and optimized structures that are impractical or impossible to create with traditional manufacturing practices. Among several mainstream AM methods, powder bed fusion is compatible with both plastics and metals, and thereby allows construction of a wide spectrum of end-use parts. A significant challenge in exploring this process from a research perspective is the predominance of commercial systems which are costly and offer limited flexibility to the user. To address this challenging lack of access, this thesis develops a low-cost and open-architecture laser powder bed fusion metal printer to enable the exploration of new materials and process concepts. Starting with a broad review of additive manufacturing, this thesis then explains the powder bed fusion process and reviews the design considerations for powder bed fusion equipment. This understanding is then applied to design an open-architecture galvanometer-driven optical scanning system. In addition, two deposition chambers are constructed, including a high-pressure vessel with a novel multi-layer recoating build platform that allows for the study of pressure in the powder bed fusion process. The operational performance is then evaluated, and the capability to achieve programmed scanning of the laser is demonstrated through point-wise and raster scan melting.