Development of calcium-based grease from coconut oil methyl ester and evaluation of its tribological properties

Coconut oil has excellent tribological properties compared to many vegetable oils, but its deprived pour point characteristics restrict its use as base oil in the development of lubricants. Hence, through chemical modification (alkali-catalysed transesterification), coconut oil is converted into coconut oil methyl ester (CME) thereby improving the pour point from 27 degrees C to -5 degrees C. In the present study, calcium based grease was developed from coconut methyl ester and its tribological properties were evaluated and compared to a commercial sample of the same grade. NLGI grade 3 grease was developed by mixing calcium stearate thickener with CME having premixed additives (TCP-antiwear, Oleic acid-antifriction and Eva-viscosity improver). Tribological properties (consistency, rolling stability, water washout, friction, wear, and corrosion) of the newly formulated grease were evaluated and compared to a commercial sample. Operating temperature of this newly formulated grease was found to be between -7 degrees C and 108 degrees C. Performance of the grease samples was studied using 0.5 HP centrifugal pump. Efficiency, discharge and power consumption of the pump were found to be 6.9%, 1.8% and 4.7% more efficient while using newly formulated grease when compared to commercial sample. These tribological and performance studies infer that the newly formulated grease was competent enough with the commercial sample.