A SUPERIOR PTFE POWDER FOR GREASE
This paper discusses the use of polytetrafluoroethylene (PTFE) as an anti-friction and anti-wear additive, grease formulation guidelines, and a modified four-ball friction and wear test. PTFE powders were formulated in grease with only base oil and lithium 12-hydroxystearate thickener. Standard four-ball friction and wear tests were performed to evaluate seven grades of PTFE. However, run-in effects interfered with this comparison. The standard test procedure was modified by gradually applying the load in a ramp. This modification significantly reduced run-in effects. One PTFE powder gave superior performance in simple lithium grease and supported loads up to 180 kgf, the limit of the test machine. PTFE has the inherent ability to function as an anti-friction and anti-wear additive; its performance depends on the specific PTFE powder and grease formulation.