Process planning for multi-axis laser-aided manufacturing process

Solid Freeform Fabrication (SFF) refers to a class of rapid manufacturing process that builds parts by incremental material deposition and fusion of thin 2-1/2 dimensional layers. Over this past decade, SFF has taken the manufacturing industry to new heights. However, parts produced by SFF processes exhibit a stair-step material texture due to the presence of 2-1/2 dimensional layers, exhibit limited material properties and long postprocess time due to the support structures. These issues are addressed by a modified SFF process call Laser Aided Manufacturing Process (LAMP). LAMP is a novel layered manufacturing process in which building a part without any support structure is possible because of the presence of the five-axis motion system. In LAMP, the layers are truly three dimensional in nature and are built using a combination of material addition and material removal processes. The need for an automated and robust process planner is more in the case of LAMP as it attempts to build fully functional parts directly from CAD models. This dissertation focuses on the process planning issues in LAMP.; The major issues in process planning for LAMP involves the generation of 3-D layers and generation of deposition and CNC cutter paths for these 3-D layers. In LAMP, the CAD model (currently STL format) is sliced into 3-D layers of varying building direction and thickness based upon geometric criteria. The layers are further decomposed into overlapped area and overhang area. Different deposition methods are applied to them, respectively. The overhang area is deposited in the thin-walls. In order to improve the final geometry of layers, the CNC cutter path needs to be generated. The curve and surface construction are involved when the process planner attempts to generate the deposition path and CNC cuter path for the layers. Different from the current layered manufacturing processes of which build direction is fixed throughout the process, the orientation of the part can affect the non-support buildability in the multi-axis hybrid manufacturing process. However, each orientation that satisfies the buildability and other constraints may not be unique. In this case, the final optimal orientation is determined based on build time. The build time computation algorithm for multi-axis hybrid system is presented in this paper. To speed up the exhaustive search for the optimal orientation, a multi-stage algorithm is developed to reduce the search space. However, the laser nozzle and tool accessibility problems need to be considered in automating the generation of deposition paths and CNC cutter paths. Several parts of varying complexity were built using this process planner and the results will be discussed.