Magnetorheological preparation using electromagnetic-permanent magnet composite excitation for the fabrication of variable cutting edge

Variable cutting edge adapted to the non-uniform cutting load can extend tool life and improve machining quality. However, complex geometries render efficient, high-quality cutting edge preparation extremely challenging. This paper proposes a novel design method for a magnetic field generator with electromagnetic-permanent magnet composite excitation, and a magnetorheological preparation process is developed that can be used to manufacture tools with variable edges. Based on the principle of magnetic field superposition, the influence of magnet arrangement on the magnetic field distribution is investigated, and a design for a magnetic field generator that can generate a high magnetic induction strength and present a specific distribution gradient magnetic field is obtained. The effects of process parameters on the material removal rate and edge surface roughness were investigated via experimental methods, and the process parameters were optimized. The results show that the electromagnetic-permanent magnet composite magnetic field generator can produce an inverted “U”-shaped magnetic field distribution to meet the demand for variable edge preparation, and the magnetic induction strength increases by approximately 155 mT. The optimized process parameters are obtained using the response surface optimization. A variable carbide tool edge with edge radii varying asymptotically from 54.929 to 26.313 μm and a surface roughness of 0.139 μm was prepared. This study is of positive significance for improving and developing the precise design and controllable preparation of high-performance tools.