Rolling Friction Torque in Ball-Race Contacts Operating in Mixed Lubrication Conditions

• Published in: Lubricants Vol. 3; no. 2; pp. 222 - 243
• Main Authors: Balan, Mihaela Rodica D, Houpert, Luc, Tufescu, Ana, Olaru, Dumitru N
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.06.2015
• Subjects: Computational fluid dynamics; elastohydrodynamics; Fluid flow; Friction; Lubricants; lubricated contacts; Lubrication; Mathematical models; rolling friction; Rotational; thrust ball bearing; Torque
• ISSN: 2075-4442; 2075-4442
• DOI: 10.3390/lubricants3020222

Based on a theoretical model and an experimental methodology for defining the friction torque for lubricated conditions in a modified thrust ball bearing having only three balls, the authors experimentally investigated the influence of the lubricant parameter Λ on friction torque for mixed IVR (isoviscous rigid) and EHL (elastohydrodynamic) lubrication conditions. The experiments were conducted using ball diameters of 3 mm, 3.97 mm and 6.35 mm loaded at 0.125 N, 0.400 N and 0.633 N. Two oils of viscosity 0.08 Pa*s and 0.05 Pa*s were used and rotational speed was varied in the range 60-210 rpm to obtain a lubricant parameter Λ varying between 0.3 and 3.2. The experiments confirmed that the measured friction torque can be explained using hydrodynamic rolling force relationships respecting the transition from an IVR to an EHL lubrication regime.