Studies on surface integrity and its optimisation in turning Ti-6Al-4V

The present work focus to assess desired machining parameters, speed, feed, depth-of-cut and rake angle for simultaneously optimising surface roughness and residual stresses induced during turning of Ti-6Al-4V with TiAlN coated tungsten carbide tools. Experiments have been conducted using L9 orthogonal array based design of experiments. The residual stresses induced in the workpiece after turning have been measured using X-ray diffraction system where as the roughness has been measured using portable surface roughness tester. The feed has been identified as the most significant parameter for the turning operation, according to the weighted sum grade of the residual stresses and surface roughness. From this investigation, it is suggested that for machining titanium alloy with TiAlN coated cutting tools, one should use the cutting speed at 75 m/min, feed at 0.25 mm/rev, depths-of-cut at 0.25 mm and a back rake angle at -7 degrees to achieve compressive or minimal tensile residual stresses and good surface finish.