Formation of the stribeck curve in hydrodynamic journal bearing applications under the influence of vegetable and mineral lubricants

This study aims to experimentally examine the Stribeck Curve, which is critically important in the design of journal bearings, by analyzing in detail the relationships between the coefficient of friction, speed, and load using different lubricants and materials. The lubricants used in the study include conventional mineral oils (5W-30 and 15W-40) as well as vegetable oils (soybean, safflower, sunflower, olive, and corn oils), which were tested in blended forms to evaluate their performance. The experiments were conducted using the PA Hilton Journal Friction Apparatus HFN 5 available at Konya Technical University. The relationships between the coefficient of friction and speed-load variables were analyzed on RG-5 and CuSn12 bronze bearing materials in accordance with the Stribeck Curve. Friction coefficients were measured at various speeds (90, 150, 300, 450, 600, 750, 900, 1020, 1200, 1350, and 1500 rpm) and loads (0, 20, 40, and 60 N). The lubrication conditions were thoroughly evaluated, and the effects of lubrication types on energy efficiency were investigated. The findings showed that vegetable oils could be used as alternative lubricants in industrial applications, and the effects of blends on the coefficient of friction provided certain advantages when compared to mineral oils. Consequently, this study makes a significant contribution to the design of journal bearings in terms of energy efficiency and performance optimization.