Friction and Wear Characteristics and Mechanism Analysis of Load and Nano MoS₂ Additive on Circular Hammerhead-Bar

Aiming at solving the wear problem of the arc-shaped contact surface between the circular hammerhead and the bar in precision blanking, the tribological performance of GCr15 steel block-45 steel column tribo-pair was dertermined on a WTM-2E controllable atmosphere micro-friction and wear tester, under lubrication of oils containing nano-MoS₂ additive (mass fraction of 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.7%), focusing on the friction and wear results under different loads. The worn surface of GCr15 steel was observed by scanning electron microscopy and analyzed by energy dispersive spectrometer. The possible mechanisms of lubrication and self-repair were discussed. The results show that increasing the applied load increased the contact stress, friction coefficient and wear. The wear regime varied from mild abrasive wear to adhesive wear. Friction coefficient and wear first decreased and then increased as the mass fraction of MoS₂ additive increased. Oil with the mass fraction of MoS₂ additive of 0.1% to 0.3% provided good lubrication. By comparing the noise, vibration speed and temperature rise of the tribo-pair, oil with 0.1% nano-MoS₂ additive showed the best tribological performance.