CNC machine tool (or CNC lathe) refers to an automatic machine tool equipped with a program control system. The control system can logically process the program specified by the control code or other symbolic instructions and decode it so that the machine tool operates and the parts are processed.

Generally, the steel blackening (black oxidation) treatment can effectively improve the corrosion resistance, but the protective effect is still quite limited. Oil immersion or subsequent rust prevention treatment is still required to really improve the corrosion resistance and lubricity of the blackened layer.