Optimal build orientation based on material changes for FGM parts

The frequent changing of materials in the functionally gradient material (FGM) part printing process is detrimental to the build time, material, quality, and system stability. Thus, the number of material changes (NMCs) is adopted as a criterion to select the best build orientation. In this paper, the NMCs of a FGM part are formulated as a multiple of a NMC and a slicing function. First, an FGM part is voxelized and discretized into material patterns. Then, the NMC function for each layer is obtained by counting the number of material patterns in a layer. Finally, the voxel model is adaptively sliced with the improved layer depth normal image techniques. This algorithmic procedure can compute the NMCs for an arbitrary orientation of any FGM parts. To find the best orientation, the entire orientation space is converted to an extended Gaussian image (EGI) using a Gaussian map, considering the geometric and material data for a FGM part. To accelerate the searching process, a point clustering algorithm is designed to select the-most-possible candidate orientations to reduce the orientation space to 1/10 similar to 1/20. Five example FGM parts are tested to demonstrate the algorithm's abilities and efficiency.