Surface integrity of finished turned Ti–6Al–4V alloy with PCD tools using conventional and high pressure coolant supplies

Abstract

Surfaces generated when machining Ti–6Al–4V alloy with PCD tools using conventional and high pressure coolant supplies was investigated. Longer tool life was recorded when machining Ti–6Al–4V with high-pressure coolant supplies and the recorded surface roughness R a values were well below the tool rejection criterion (1.6 μm) for all cutting conditions investigated. The micro-structure of the machined surfaces were examined on a scanning electron microscope. Micrographs of the machined surfaces show that micro-pits and re-deposited work material were the main damages to the surfaces. Micro-hardness analysis showed hardening of the top machined surfaces when machining with conventional coolant while softening of the subsurface layer was observed when machining under high-pressure coolant supplies. The later is probably due to lower heat generated, with the consequent tempering action when machining with PCD tools with high-pressure coolant supplies. The microstructure below the machined surfaces had minimal or no plastic deformation when machining with conventional and high-pressure coolant supplies.