Why Is Chrome Plating Applied to Piston Rod Surfaces?

Among the components of a hydraulic cylinder, the piston rod is a critical part. Since the piston rod must meet specific mechanical performance requirements, its proper function directly affects the performance of other components in the system. Therefore, strict performance standards are required for the hydraulic cylinder piston rod, such as good lubrication, corrosion resistance, and high tensile strength. Additionally, the piston rod must provide a low-friction surface due to its reciprocating movement through seals, wipers, and bearing surfaces.

To meet these various functional and performance demands, the piston rod must be chrome plated.

Piston rods are typically made of high-strength carbon steel to meet mechanical strength requirements. They are then chrome plated to achieve a hard, smooth, and corrosion-resistant surface finish. Hard chrome plating is a complex electrochemical process, where the rod is submerged in a heated bath of chromic acid. With the application of electric current between the rod and a counter-electrode, chromium metal is slowly deposited onto the rod surface through a controlled electrochemical reaction.

After chrome plating, the coating hardness can reach HV1100, with a smooth, uniform layer and strong distribution ability. As a result, chrome plating not only gives the piston rod the necessary performance characteristics, but also improves its surface hardness, brightness, and enhances the bonding strength between the coating and the base metal.