The frictional properties of piston-rod seals is an important issue in hydraulic systems. Accelerated wear can result from high static and dynamic friction. Equally the overall efficiency of the hydraulic system can be decreased with excessive friction leading to undesirable stick-slip and high breakaway forces after rest.
Burnishing, is used on piston rods to improve their surface finish. Unlike grinding, roller burnishing is a compressive technique that creates a highly polished surface relatively free from surface ridges or apserites. This more highly polished surface allows seals to operate more effectively.
Roller Burnishing uses a series of tapered, highly polished and hardened rollers positioned in slots within a retaining cage - a bit like a bearing.
Diamond Burnishing does cut, but produces a fine mirror-like surface finish which eliminates conventional grinding and polishing. It is especially useful for smaller pieces.