Optimization of Surface Integrity and Fatigue Life in Hard Turning of K110 Tool Steel

The influence of various machining process parameters on surface integrity elements (e.g. surface roughness and surface residual stress) and fatigue life of hard metals is an important area of engineering. This study investigates the effect of various turning parameters on the surface integrity and fatigue life of K110 hard tool steel. The determination of residual stress was performed by a non-destructive testing technique using X-ray diffraction analysis (XRD). The experimental work extended to perform fatigue experiments using rotary bending machine which was designed and manufactured to assess the fatigue behavior under rotating bending stresses. In this investigation, single optimization of four methodologies (Taguchi method, second-order polynomial, Artificial Neural Network (ANN) and Group Method of Data Handling (GMDH)) are carried out to determine the optimum conditions that lead to the highest value of fatigue life. This investigation studies optimizing the machining process parameters namely; rotational speed, feed rate, depth of cut, and tool nose radius on the surface roughness, surface residual stress and subsequent fatigue performance of K110 tool steel of 62 HRC. The experiments were designed based on the Taguchi method L18 orthogonal array. The minimum surface roughness and maximum surface residual stress in Taguchi method can be obtained at speed of 4000 rpm, feed rate of 0.1 mm/rev, depth of cut of 0.2 mm and nose radius of 0.8 mm. However, maximum fatigue life can be obtained at speed of 1500 rpm, feed rate of 0.1 mm/rev, depth of cut of 0.3 mm and nose radius of 0.8 mm.