In order to ensure machining accuracy, roughing and finishing are best performed separately. During rough machining, the cutting amount is large, the cutting force and clamping force of the workpiece are large, the heat generation is large, and the machining surface has a significant work hardening phenomenon. There is a large internal stress in the workpiece. If rough and rough machining Continuously, the precision of the finished part will be quickly lost due to the redistribution of stress. For some parts requiring high machining accuracy. After roughing and before finishing, low temperature annealing or aging treatment procedures should also be arranged to eliminate internal stress.