Effect of triangular oil pockets on friction reduction

Abstract

The effect of the apex angle of triangular oil pockets created on a disc surface on friction was studied. Experiments were carried out using an Optimol SRV5 tribotester equipped with a pin-on-disc module under unidirectional lubricated sliding. Both the sample and counter sample was made of steel of 45 Hardness Rockwell C (HRC) hardness. Only 1 ml of oil was put to the inlet side of the contact area at the beginning of each test. All textured surfaces had the same pit-area ratio and an average depth of dimples. Oil pockets were positioned in the spiral array. It was found that the effect of the apex angle of triangular dimples on friction reduction was important. When the normal load was lower, the smallest coefficient of friction was achieved for the sliding pair with a disc apex angle of 60°. Under a larger normal load, a higher apex angle corresponded to a higher coefficient of friction.

A review of advances in tribology in 2020–2021

“…However, little effect or even negative effects were also reported compared with texture-free surfaces, if the surface texture is not appropriately designed and/or fabricated in some cases. Laser surface texturing is most studied and a widely applied technology, which has been used in surface modification of piston ring [479], on stator surface in ultrasonic motors [480], on the Ti-6Al-4V biomedical materials combined with chemical assembly of a graphene oxide film [481], on a Si 3 N 4 disc sliding in water against a Si 3 N 4 ball [482], on UHMWP samples for bio-implants [483], on TC4 (Ti-6Al-4V) titanium alloy disc sliding against a UHMWP ball in simulated body fluid (SBF) [484], on a lead bronze coating surface [485], on a 42CrMo4 steel disc reciprocating under starved lubrication [486], and on the water-lubricated thrust ball bearing washer surface made of high density polyethylene (HDPE) specimens, manufactured using 3D printer technology [487]. Ding et al [488] constructed 3 types of dimpled surfaces, type A: 'wide & deep' by pico-second laser ablation, type B: 'narrow & shallow' by one-step post-polishing type A, and type C: 'wide & shallow' by two-step postpolishing of type A, on a smooth AMS5630 440C stainless steel sample for investigation the effect of surface texturing on material transfer behavior of the X1 PTFE/glass fiber woven fabric composite (bonded by phenolic resin) when sliding against the textured steel samples.…”