The high strength composite fiberglass backing permits optimal strength and rigidity, with a modulus of elasticity of approximately 6 x 10^6 PSI. This property allows the FW bearing to be rigid enough to support heavy loads and pliant enough to tolerate moderate shaft misalignments without over-stressing the bearing edges. The bearing surface is composed of a uniquely designed woven structure of PTFE filaments, which exhibit tensile strengths twenty times greater than PTFE resins. As a result, the bearing is not subject to cold flow under high loading conditions. These PTFE super-filaments are also the primary mechanism for allowing the FW product to operate in a true self-lubricating mode. No secondary lubrication is necessary, even during start-up conditions, due to the film transfer self-lubrication process.
At start-up the, the PTFE undergoes a phase change and smears around the mating pin surface. As the PTFE film develops, it transfers from the inner diameter to the outer diameter of the pin, smoothing out any macroscopic surface imperfections and allowing the bearing to have a very low coefficient of friction and minimal long-term wear, even under high loading conditions. In some conditions, as much as 0.001" of wear may occur during the break-in period, while in other operations, break-in wear may be negligible. The elapsed time for break-in is PV (Pressure and Velocity) dependent. The equilibrium wear rate varies from operation to operation, due to a number of factors including: loads, speeds, shaft hardness, material, and shaft surface finish. For more specific guidance on the break-in period to anticipate given your specific application, please contact Daemar.
Following the break-in period, the wear rate stabilizes, remaining relatively constant for the bearings' life. Testing of the Fiber Series Bearing at 22,500 pounds, with 50° oscillation angle, resulted in stable wear under 0.005" at over 1.5 million cycles.
Daemar's FW Series bearings are designed to minimize wear; however, the bearing wear is affected by the general operating conditions, such as speed, sliding distance and load. With intermittent rotation or oscillation, radial wear should be negligible over thousands of hours. Hard chrome plating gives excellent wear performance and protects the shaft from corrosion. Coatings such as chrome, electroless nickel, or nitro carbonizing are all common treatments for shaft materials used with these bearings. |