Friction analysis of Waste Palm Methyl Ester (WPME) under Stribeck lubrication regimes

Abstract

This paper aims to investigate the tribological friction using the Stribeck curve lubrication regime using an alternative source of biodiesel. Replacement of current usage of fossil fuels is essential, therefore, it is important to develop a proper recycling, renewable and sustainable product that reduces global warming. Biodiesel also known as Fatty Acid Methyl Ester (FAME), is biodegradable, produced from a renewable source, non-toxic, and produces a minimum greenhouse gas emissions. To reduce raw material cost, waste cooking oil is one of the most suitable replacements of vegetable oil for biodiesel synthesis. Rheological behavior of Waste Palm Methyl Ester (WPME), such as kinematic viscosity, density, and acid value, was measured based on EN14214 and compared with Palm Methyl Ester (PME). The friction performance of WPME was evaluated using a pin on the disc tribometer machine. The influence of different operating conditions such as loads at 1kg, 2kg, 3kg and 4kg and sliding velocity range from 0.00625 m/s to 4 m/s were optimized in this study. The preliminary result shows significant changes on the Stribeck curve concerning the sliding speed and also loads. It is found that as for the same entrainment velocity and surface roughness, a higher load will initiate a higher temperature, thus lead to decreasing the viscosity and coefficient of friction. In summary, WPME is highly considered as a potential waste that can replace the current energy source.