Investigations on the Machining Performance using Solid Lubricant Mixed with Varying Proportions in Vegetable Oil during Hard Turning

Abstract

The solid lubricant assisted machining is gaining more attention from last decade as use of cutting fluids becoming more and more prevalent around the world due to health and environmental concern. However, very few studies reported on use of solid lubricants during machining. With this view, in the present work, hard turning experiments with boric powder as a solid lubricant mixed with varying proportions in vegetable oil (refined sunflower oil) were performed using coated carbide tool. Machining performance in terms of surface roughness and cutting forces (tangential, feed and radial components of force) were investigated at different cutting conditions under dry and with three varying proportions of boric powder namely, 1%, 5% and 10% mixed with vegetable oil. It has been observed lower values of surface roughness and cutting forces when using solid lubricant assisted hard turning (SLHT) as compared to dry hard turning. Lowest values of surface roughness were observed when using 10% proportion of boric powder mixed with vegetable oil. However, cutting forces although observed to decrease with increasing percentage of proportion of boric powder in lubricating oil, no significant reduction; especially in tangential and feed components of forces, were observed when using 5% and 10% proportion of boric powder mixed with refined sunflower oil. SLHT experiments were also performed under mist lubrication (Mist-SLHT) with a view to assess the feasibility of variants of solid lubrication system in hard turning.