Evaluation of lubrication performance of RBD palm stearin and its formulation under different applied loads

The lubrication performance of refined, bleached and deodorized (RBD) palm stearin as an alternative lubricant was evaluated using pin-on-disk tribotester. Zinc dialkyl-dithiophosphate (ZDDP) additive with 0 wt%, 1 wt%, 3 wt% and 5 wt% concentration was added to improve the lubrication performance of RBD palm stearin. The experiment was repeated using commercial mineral oil (SAE 40) for comparison purposes. The lubrication performance of lubricant was evaluated in terms of friction-reducing and anti-wear performance. The results reveal that when RBD palm stearin was stand alone, it has higher coefficient of friction (COF) and wear scar diameter (WSD) than that of SAE 40. The addition of ZDDP shows an improvement in both friction-reducing and anti-wear performance of RBD palm stearin. It shows that PS+ 5 wt% ZDDP gave better friction-reducing performance than SAE 40.