Research on tribological characteristics of a new grease produced by mixed vegetable oil for low-speed application

This study explores the potential of vegetable oils as a sustainable alternative to mineral oils in grease formulation. The research focuses on producing bio-based greases using non-edible vegetable oils, specifically a blend of castor and jatropha oils in different proportions. Lithium hydroxide (LiOH) used as a thickener, while zinc dialkyldithiophosphate (ZDDP) additive was added to improve tribological properties of the bio- grease. According to factorial matrix, ten samples of bio-grease with different amount of base oil, thickener and additive were produced and tested for cone penetration, dropping point, wear, coefficient of friction, and viscosity using ASTM standards. Results showed that the bio-grease sample containing 3% thickener, 2% additive, and 10% jatropha oil (with the remaining 85% being castor oil) exhibited the best tribological characteristics among the samples. This sample achieved a wear value of 0.38mm and coefficient of friction value of 0.03511. The results indicate that a new produced bio-grease sample outperforms both the baseline research work and standard mineral EP3 greases. The blended oils' fatty acid composition contributed to improved film formation and lubrication, resulting in lower wear and friction coefficient values. This study concludes that blended non-edible vegetable oil with thickeners and additives can be used to formulate bio-grease, an environmentally friendly alternative to mineral-based lubricants.