Optimization of surface roughness and hole diameter accuracy in drilling of EN-31 alloy steel – A TGRA based analysis

Abstract

The paper presents an assessment of the effect of the machining parameters in drilling of EN-31 alloy steel on surface roughness and hole diameter accuracy. The EN-31 steel is commonly used for bearing surfaces and thus is also known as bearing steel. The machining experiments were conducted on CNC Vertical Machine Centre. Design of experiment based on Grey Taguchi method with three independent factors (spindle speed, feed rate and point angle of drill) and two responses (surface roughness and hole diameter accuracy) has been used. An L27 Orthogonal array has been used to develop relationships for predicting surface roughness and hole diametrical error. Out of three process parameters, the point angle appears to have the strongest effect on the multi-performance characteristics. The order of importance of the controllable factors to the multi-performance characteristics appears to be point angle, spindle speed and feed rate.