Dry drilling of alloy Ti–6Al–4V

Abstract

This work is focused on the combined study of the evolution of tool wear, quality of machined holes and surface integrity of work-piece, in the dry drilling of alloy Ti–6Al–4V. Tool wear was studied with optical microscope and SEM–EDS techniques. The quality of machined holes was estimated in terms of geometrical accuracy and burr formation. Surface integrity involves the study of surface roughness, metallurgical alterations and microhardness tests. The end of tool life was reached because of catastrophic failure of the drill, but no significant progressive wear in cutting zone was observed previously. High hole quality was observed even near tool catastrophic failure, evaluated from the point of view of dimensions, surface roughness and burr height. However, microhardness measurements and SEM–EDS analysis of work-piece showed important microstructural changes related with a loss of mechanical properties. Depending on the application of the machined component, the state of the work-piece could be more restrictive than the tool wear, and the end of tool life should be established from the point of view of controlled damage in a work-piece.