Grade classification of bio-based lube oil by multi-attribute decision making methods

Abstract

Abstract An appropriate selection of bio-based lubricants for metal cutting applications in a manufacturing process is a very significant and challenging task due to enormous varieties and properties. The objective of this work is to select appropriate bio-based lube oil intended for a metal cutting operation such as tapping of hard materials. In this work, fourteen vegetable-based oils as alternatives and their nine relevant characteristics such as oxidation stability, anti-wear scar diameter, viscosity index, pour point, flash point, coefficient of friction, extreme pressure properties, availability and cost have been considered for assessment. A logical method to select suitable vegetable-based oil using multi-attribute decision making (MADM) methods such as AHP, COPRAS and WASPAS are proposed in this paper. AHP is implied for the assessment of the relative significant weights of the attributes. The ranking of the alternatives was subsequently examined after calculating the utility degree in the COPRAS method. It has been found that Coconut oil shows highest utility degree i.e., more than 95%, followed by Palm oil 87.94% and Jatropha oil 70.72%. Also, the ranking was confirmed by using WASPAS comparative tool. Based on the results of these two methods, it was observed that palm oil, coconut oil and Jatropha oil could be the best suitable lube oil for tapping operation. Tribological evaluation of these lube oils has been suggested using an appropriate set of additives.