The high frequency piston rod or induction hardened piston rod is processed by high frequency quenching technology, and then polished by mirror surface. The hardness can reach HRC58-62. Compared with ordinary piston rod, it has the characteristics of friction resistance and corrosion resistance.  

High-frequency quenching is mainly used for surface quenching of industrial metal parts. It is a heat treatment method that causes a certain induction current on the metal surface, rapidly heats the surface of the parts, and then rapidly quenches the parts.  

Principle of high-frequency quenching:  Put the piston rod with a hollow copper pipe wound as sensor, after the ventilation with high frequency alternating current (ac), formed in the surface with the frequency of the induced current, the workpiece surface or local heating quickly (within a few seconds to heat up to 800-1000 degrees Celsius, the center is still close to room temperature) several seconds after rapid spray immersion cooling, spray or immersion cooling quenching work done,   the piston rod surface or local to achieve the corresponding hardness requirements .