Investigation on Tool Life and Surface Integrity when Drilling Ti-6Al-4V and Ti-5Al-4V-Mo/Fe

Machinability study on the drilling of two alpha beta titanium alloy series, Ti-6Al-4V and Ti-5Al-4V-0.6Mo-0.4Fe were conducted using an uncoated carbide drill. The effect of cutting speed on tool life, tool failure mode, cutting force and surface integrity of the drilled surface were discussed. Results showed that Ti-6Al-4V exhibited a more superior machinability property when compared to the Ti-5Al-4V-Mo/Fe alloy system. The tool wear progression when drilling Ti-6Al-4V was lower than that of Ti-5Al-4V-Mo/Fe. The tool experienced similar failure mechanisms which were non uniform wear and chipping when drilling both alloys. At high cutting speed and after prolonged machining, excessive plastic deformation was observed on the subsurface layer of the drilled surface which resulted in increase in the hardness value

Mechanical drilling processes for titanium alloys: a literature review

Titanium and its alloys (Ti) are attractive for many applications due to their superior properties. However, they are regarded as hard-to-machine materials. Drilling is an important machining process since it is involved in nearly all Ti applications. It is desirable to develop cost-effective drilling processes for Ti and/or improve the cost-effectiveness of currently-available processes. Such development and improvement will be benefited by a comprehensive literature review of drilling processes for Ti. This paper presents a literature review on mechanical drilling processes for Ti, namely, twist drilling, vibration assisted twist drilling, ultrasonic machining, and rotary ultrasonic machining. It discusses cutting force, cutting temperature, tool wear and tool life, hole quality (diameter and cylindricity, surface roughness, and burr), and chip type when drilling of Ti using these processes