The sliding movements of components, i.e. a piston in a tube, risk metal-to-metal contact that will damage and score the surfaces and eventually cause seal damage, leakage and component damage. To prevent this, piston and gland should have a brass bearing surface or precision guide elements such as wear rings, wear bands, guide rings or bearings. The greater the side load forces, the stronger the wear ring material must be. Wear rings should last longer than the seals as they are the only things stopping expensive damage to the cylinder.
The function of the wear ring is to help keep the piston centered, which allows for even wear and pressure distribution on the seals. Popular wear ring materials include glass filled Nylon, bronze filled PTFE, glass filled PTFE, Phenolic and carbon-fiber reinforced compression molded. Wear rings are used in both piston and rod applications. Wear rings are available in butt cut, angle cut and step cut styles.
Wear rings should always be installed on the lubrication (wet) side of the seal for best performance. For rod glands, the wear ring should be on the pressure side of the rod seal. For pistons, if only one bearing is to be used, it should be on the side of the piston opposite the rod. This arrangement keeps the piston wear ring further away from the rod wear ring. This becomes critical when the rod is at full extension and provides better leveraging of the two bearing surfaces.
Wear rings are available in different thicknesses, OD’s (Outside Diameters) and Height. Unless you know the dimensions, it is best to match the part when replacing the Wear Ring. Rocket Seals carries primarily 1/8” thickness with a limited selection of other thicknesses. We also carry a wide range of standard sizes of nylon wear rings along with some phenolic, along with a limited range of metric sizes and a number of sizes of flexible guide bearing you can cut to the size you need. Visit our website @ Rocketseals.com 24/7 or call us at 1 (800) 445-7803 to talk with any of our staff.