Taguchi-Grey Optimization of Tribological Characteristics of Blended SAE 40 Lubricant

A high proportion of lubricants used in automobile engines are mineral-based oil. The depletion of oil reserves and the concerns (non-biodegradable, toxic and environmental issues) of mineral based lubricants prompted the research for a viable alternative. Vegetable oil has been proposed as a potential substitute for the mineral-base lubricants due to its natural and eco-friendly characteristics. In this study, optimization of tribological characteristics of blended SAE 40 produced from SN 500 mineral oil, Shea butter bio-base oil, and viscosity improver was carried out on pin-on-disc tribometer. Taguchi and Taguchi-grey relational method were used to optimize the load and sliding speed to obtain the minimum specific wear rate and coefficient of friction (COF) for the blended SAE 40. The optimum parameters using Taguchi’s and Taguchi-grey relational analysis methods are 8 N load and 5 cm/s sliding speed. At this optimum condition, the minimum specific wear rate of 0.007 mm3 /Nm and minimum coefficient of friction of 0.001 were observed. The developed mathematical model was validated against the experimental results. Deviation of about 5% was obtained in the wear rate model using Taguchi model. Also, the correlation of about 89.77% was observed between the model developed using Taguchi-grey relational model and experimental values. This implies that the two models can be used to predict the tribological properties of blended SAE 40 lubricant.