Lubrication of sliding point contacts of AISI 52100 steel — the influence of curvature

The lubrication mechanism of fully submerged sliding point contacts of non-oxidized AISI 52100 steel has been studied as a function of radius of curvature in the contact area. The results of experiments, performed with hemispherically tipped pins with radii of curvature R₁ ranging from 1 mm to 23 mm in contact with the curved surfaces of rings of 76 mm diameter, corroborate the existence of three well-defined lubrication regimes, i.e. a regime of thin oil film lubrication, a regime of boundary lubrication and a regime of virtually unlubricated contact. At small radii of curvature (i.e.R₁ = 1 mm and 5 mm), the contacts derive their load-carrying capacity almost entirely from the presence of a boundary lubricant film. At R₁ = 23 mm, lubrication is mainly due to the presence of a thin oil film.