CHARACTERIZATION OF THE LUBRICATING ACTION OF OILS UNDER BOUNDARY LUBRICATION CONDITIONS

Polyalphaolefin (PAO) and polypropylene glycol (PPG)-based lubricants as well as mineral oils were tested to characterize their wear reducing performance under boundary lubrication conditions, using the ISO 7148 test method, which was originally developed for the characterization of bearing materials. This test method has practical value with respect to developing lubricants for use in sliding contacts, such as occur in worm gear drives. It is found that the wear reducing action of PAO-based lubricants is significantly better than that of mineral oils. PPG fluids perform equally veil or slightly better than PAOs. Provided that viscosities are in line and additives are compatible, contamination of PAOs with mineral oils has no or only marginal effect on wear reduction.