Friction Characteristic of Mineral Oil Containing Palm Fatty Acid Distillate using Four Ball Tribo-tester

Vegetable oil was one of the main sources of lubricating oil before the discovery of petroleum. Nowadays, due to vegetable oil's poor performance at high temperatures and oxidation, it has not been widely used in the industrial sector. However, the fatty acids contained in vegetable oils may significantly reduce the frictional coefficient. To optimize lubrication, vegetable oil can be mixed with mineral oil. In this paper, palm fatty acid distillate (PFAD) was mixed in mineral oil and it lubricating properties were tested. Palm oil is one of the major vegetable oils produced in the world, and PFAD is one of the by-products of the palm oil refinery process. It is classified as a non-edible oil, and therefore, the increased use of this product for mechanical lubrication would not affect the production of cooking oil, the food chain or increase food prices. The mixing percentage (PFAD to mineral oil) varies from 5% to 25% of the total mass. Testing was conducted using a four-ball tribotester accordance with the American Society for Testing and Materials (ASTM) standard 4172. The results show that by mixing a 20 % total mass of palm oil in the mineral oil, the coefficient of friction reached its lowest value. The wear scars on the ball bearings lubricated with this mix of oil also showed acceptable diameter values when compared to other conditions. From these results, it can be concluded that the performance of the mineral oil could be enhanced by mixing it with vegetable oil (instead of mineral oil). However, the percentages should be determined properly. (C) 2013 The Authors. Published by Elsevier Ltd.