Piston rod: is the connecting component which can support the piston to do work,mostly used in the moving components of oil cylinder and air cylinder, which is the frequently moving component, with high technical requirements. Take the hydraulic oil cylinder as an example: it is composed of cylinder tube, piston rod, piston and end cover. The service life and stability of the oil cylinder directly depends on the quality of the piston rod. The piston rod has high processing requirements, the surface roughness is Ra0.4 ~ 0.8um, and has strict requirements on coaxiality and abrasion resistance.