The Effect of Temperature on Magnetic Properties and Surface Integrity in Nd2Fe14B Permanent Magnets, Under Dry and Wet Grinding for Automotive Applications

Electric motors transform the electrochemical energy into mechanical energy needed for the vehicles' motion. Given that the transition from internal combustion engines to electric vehicles is likely to be the main driver of sustainable transportation, high-performing electric motors will be increasingly important for this transition. Herein, the effect of the grinding process on the surface integrity and magnetic properties of NdFeB permanent magnets are investigated. NdFeB permanent magnets are most commonly used in the fabrication of permanent magnet electric motors and they are usually ground during their fabrication process chain in order to create a high-quality cylindrical rotor for subsequent mechanical assembly. In particular, the effects of wet and dry grinding processes on magnetic properties and surface integrity are studied and compared. Guided by a thermal model, the grinding process parameters are varied highlighting their effects on the underlying thermomechanical phenomena responsible for the changes in surface integrity and magnetic properties observed. Wet grinding proves to be a viable process for NdFeB magnets. Additionally, acceptable results are achieved with dry grinding, which is particularly appealing due to its sustainability. It is noteworthy that the range of process parameters yielding acceptable results is narrower.