The principal application for hard-chrome bar is as piston rods in hydraulic cylinders. The function of the piston rod is to transmit the force derived from the oil pressure acting against the piston. The bar surface is coated with a layer of chrome which has low friction, high hardness and scratch resistance as well as providing some degree of corrosion protection.

In regard to diameter tolerance, ovality, straightness and surface finish, hard-chrome bar is at least equivalent to or even better than centreless ground bar. As a final step in production, the bar is packed in a plastic sheath to protect the highly-polished surface during transport, storage and piston-rod manufacture.