Based on the principle of mechanical extrusion with smooth knife, a machining method for obtaining mirror-like smooth metal surface is obtained. Extrusion tool machining is a chip-free machining, which uses the plastic deformation of metal at room temperature to flatten the micro-roughness of the workpiece surface, thus changing the surface structure, mechanical characteristics, shape and size. Therefore, this method can achieve the purpose of dressing and strengthening at the same time, which is impossible for grinding.

No matter what processing method is used, there will always be tiny uneven knife marks on the surface of the parts, and there will be peaks and valleys.