Abstract
Hybrid manufacturing (HM), which combines additive manufacturing (AM) and subtractive manufacturing (SM), is effective for the fabrication of thin-walled complex shapes, such as impeller blades. Generally, a process planning for HM is to build a near-net shape through AM and finish its surface through SM. However, in this approach, the cutting tools are limited with long tool lengths and small tool diameters to avoid collisions between the cutting tool and workpiece. In addition, the fabrication shapes are also limited. Therefore, one possible solution is to alternate between AM and SM processes multiple times. In this approach, the workpieces are built gradually as the process progresses. Therefore, the cutting tool can easily avoid collision with the workpiece. However, melting penetration and temper color remain on the finished surfaces using the conventional process planning method with alternate multiple switching. In this process planning, AM and SM processes are alternated. Thus, the finished surfaces are remelted in the subsequent AM process. This heat input causes melting penetration and temper color. These thermal effects must be prevented because these can lead to unfinished part and deterioration of the appearance of the workpieces. Therefore, in this study, a novel process planning method that allows alternate multiple switches without thermal effects is proposed. In addition, a process planning support system that simulates SM process was developed. The SM simulation can detect collision between the cutting tool and workpiece. Using the proposed process planning method, the system plans a process in which thermal effects will not occur. In addition, a case study was conducted using a simulated impeller blade geometry. The results of the case study showed that the developed system could plan by using several cutting tools and parameters of the machining head. The system can estimate the processing time based on the cutting tool path, deposition path, SM process conditions, and AM process conditions. The results validated the developed system and demonstrated its usefulness.
