The main factors affecting work hardening of CNC machine tools are:
1. Tool geometric parameters. When the front angle of the tool is negative, the back angle is too small, and the arc radius of the cutting edge or the cutting edge is worn, the extrusion and friction of the tool on the machined surface of the workpiece will intensify, which will increase the degree of hardening and the depth of the hardened layer.
2. Cutting amount. When the feed rate of CNC machine tool is increased, the cutting force, cutting heat and plastic deformation increase synchronously, so that the degree of hardening and the depth of hardening layer increase; However, if the feed rate is too small, the cutting edge will repeatedly squeeze the machined surface, which will also increase the degree of work hardening. Increasing the cutting speed shortens the contact time between the tool and the workpiece, reduces the plastic deformation, and the increase of the cutting temperature is conducive to the recovery of cold hardness. Therefore, in general, the cutting speed increases and the degree of hardening decreases.
3. Workpiece material. The greater the plasticity of NC machine tool materials, the greater the plastic deformation during cutting, and the more serious the degree of hardening and the depth of hardened layer.