Development of a fretting wear test rig and preliminary studies for understanding the fretting wear properties of steels

Rolling element bearings experience fretting wear type of failures due to small relative oscillatory motion existing between races and rolling elements of the bearing. Small oscillatory motion between contacting surfaces that occur due to overall machine or system vibration and unexpected loads in service causes accumulation of wear debris in the contact zone and accelerate the wear process. A fretting wear test rig is designed and developed in the laboratory for understanding the fretting wear behavior of bearing materials. The test rig is designed for testing at slip amplitudes ranging from 20 to 200 μm and test frequencies ranging from 1 to 30 Hz. Preliminary studies for understanding the fretting wear characteristics were conducted on hardened and tempered bearing steel, En31 and widely employed hardened and tempered structural steel, En24 at various normal loads. Coefficient of friction during fretting tests was high during the initial stages of fretting tests and reached a steady state. The coefficient of friction depends on the normal load. Wear scar morphology reveals the nature of contact exhibited by the fretting contacts.