Strict environmental regulations are driving the automotive industry toward electric vehicles as they offer zero emissions. A key component in electric vehicles is the electric motor, where the stator and rotor are manufactured from stacks of thin electrical steel sheets. The electrical steel sheets can be cut in different ways, and the cutting methods may significantly affect the fatigue strength of the component. It is important to understand the effect of the cutting processes on the fatigue properties of electrical steel to ensure there is no premature failure of the electric motor resulting from an improper cutting process.
This investigation compared the effect of three different edge preparation methods (stamping, CNC machining, and waterjet cutting) on the fatigue performance of 0.27mm thick electrical steel sheets. To investigate the effect of the edge finish on fatigue behavior, surface roughness was measured for these different samples. It was determined that the CNC machined samples had the lowest overall roughness over the cut edge, followed by the stamped samples, and the waterjet samples with the worst finish. The fatigue life followed a similar trend where CNC machined samples had the longest life, and the waterjet samples had the lowest life under the same stress amplitude. While the CNC samples had the greatest overall life, the stamped samples could withstand the largest alternating stress out of the three cutting processes because of the residual stresses induced by the stamping process. Additionally, the stamped samples had very close life to the CNC machines samples in the high cycle regime. An investigation was carried out to determine the relationship between surface roughness and residual stress to the fatigue life of the electrical steel.