Manufacturing processes of soft magnetic composite cores for permanent magnet machines

By using the low mass density compaction, the electrical machine with soft magnetic composite (SMC) cores has shown its great advantage of the low manufacturing cost over that with silicon steels, especially in the mass production. For the laboratory prototype, wire cutting method is widely used to build the SMC cores for electrical machine. However, cutting the SMC preform block can destroy the magnetic properties of the SMC material, making that the electrical machine made in the laboratory cannot have the same performance as that in the mass production. To minimize the gap between the laboratory prototype and the mass production, the SMC cores should be made by the die compaction. However, to achieve high mass density, the compact pressure must be high and the productivity is low. On the other hand, low mass density compaction would greatly increase the productivity, but the core performance may deteriorate, which can be dealt with careful design and optimization of electrical machine. This paper presents our recent investigation on the manufacturing process of soft magnetic cores. The details of designing the die tools and building the SMC cores by using these tools are described.