Octree data structure for support accessibility and removal analysis in additive manufacturing

Abstract

Metal Additive Manufacturing (AM) processes have made it possible to build parts with complex geometric features by adopting a layer-by-layer approach. However, additional support structures are needed to support overhanging surfaces and reduce distortion that may occur in these parts. This increases the overall build time of the part and leads to additional post processing efforts for removal of support structures. Often, removal of these supports becomes difficult due to complex part features that may interfere with support removal. Further, support structures have a detrimental effect on the surface finish on the areas of the part that come in contact with the supports. Thus, minimizing the need for support structures and ensuring its maximum removal is essential for an efficient part build in AM. Part build orientation is the main parameter that influences the need for support structures to build a part. This paper presents an approach to identify the best build orientation for a part such that the overall part build time is minimized while ensuring maximum removal of supports and minimizing the contact area between the part surface and supports. A hierarchical octree data structure has been used to analyze support accessibility and the area of support in contact with part. In addition, this paper also focuses on identification of optimal number/direction of part set-ups required to remove the maximum possible support structures from a part. A 2D setup map highlighting the feasible directions of setups for support removal has also been presented. The results of these analyses have been presented with the help of four sample parts.