Synthesis of Eco-Friendly Machining Lubricants and Its Tribological Characteristics

Abstract

Use of vegetable oil as a base for the preparation of machining fluids for the replacement for mineral oil is a growing research area because of the harmful effects to the environmental degradation of soil and water affecting plants and aquatic species, health hazards to the workers, bio-degradability and carcinogenic effects. Further most of the research work is carried out by formulating cutting fluids from vegetable oils using petroleum based emulsifiers, which defeats the purpose of using vegetable oils. In the present study lubricants from vegetable oil based emulsions were formulated with food grade emulsifier polysorbate 80. Cutting fluids were formulated by using vegetable oils as a base in an aqueous solution with emulsifying agent in the ratio of 1: 20. The tribological properties of these vegetable oil emulsions were investigated using a rotary type tribometer. The tribometer has a stationary loaded pin made from EN8-steel (workpiece material) which slides over the rotating disc made of EN31-steel. The experiments were performed with two different sliding speeds and four different loads. Coefficient of friction, friction force, wear rate and surface roughness were recorded and analysed. The wear rate of the pins while lubricating with castor oil and mahua oil emulsions was low as compared to palm oil emulsion. At low speed the friction was low with castor oil emulsion, while at higher speed the coefficient of friction was low with mahua oil emulsion. A conclusion has been arrived from the experiments that the castor oil emulsion gave better lubrication properties as compare to palm, mahua and mineral oil emulsions.