Influence of grease formulation parameters on the tribological property of rice bran oil based lubricating grease

Abstract The negative environmental impacts and depletion of resources caused due to the excess usage of petroleum based products made researchers to think about an alternative biodegradable product. In the present study, rice bran oil (RBO) was used as a base oil for formulating 16 different grease samples. The thickener used was generated in situ by mixing 12‐hydroxy stearic acid (12 HSA) to calcium hydroxide at a different ratio from 1.25 to 2. The formulation parameters such as weight % of thickener, saponification time, and maximum temperature spanned the ranges 5–11 wt.%, 1–2.5 h, and 150–180°C, respectively. The tribological properties such as wear scar diameter (WSD) and friction of 16 different grease samples formulated by varying these parameters were evaluated using a standard four‐ball tester as per ASTM standards. The grease samples were characterized by evaluating the penetration value using a standard cone penetrometer. The influence of these formulation parameters on the experimentally evaluated properties was also examined in this work. The results indicated that the variation of these parameters during grease formulation has a significant influence on the evaluated properties.