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 reducin g performance under boundary lubrication conditions, using the ISO 714 8 test method, which was originally developed for the characterization of bearing materials. This test method has practical value with respe ct 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. P PG fluids perform equally veil or slightly better than PAOs. Provided that viscosities are in line and additives are compatible, contaminati on of PAOs with mineral oils has no or only marginal effect on wear re duction.