Machinalibilty of Ti-6Al-4V Under Dry and Near Dry Condition Using Carbide Tools

ABSTRACT

The effectiveness of the usage of coolant in high speed machining of highly reactive material like titanium and its alloys is still far away uncertain. For this reason, it is wiser to study the effectiveness of Minimum Quantity of Lubricant (MQL) under transient cutting speed before advancing to high speed machining. This paper discusses the effect of MQL on the machinability of Ti-6Al-4V using Physical Vapor Disposition (PVD) coated cemented carbide tools. The machinability studied parameters were the generated cutting force and the tool life. The performance of PVD coated cemented carbide tool was investigated at various cutting condition under dry and near dry (or MQL) machining. For near dry machining, two levels of coolant flow rate of 50 and 100 mL/H were investigated. The effectiveness of mist coolant was tested at three different levels of cutting speed, 120, 135 and 150 m/min. Application of mist coolant is more effective at cutting speed of 135 m/min. At this speed longer tool life was obtained when more coolant was applied. The effect of the cutting speed and coolant flow rate on the surface roughness is not significant. Surface roughness is more sensitive to the feed rate and the depth of cut. No significant effect of MQL on cutting force at early stage of machining was observed. MQL seems to be more effective when tools start to wear out, where greater contact area between tool and work piece occurs to give better lubrication effect.

Keywords:

PVD cemented carbide, dry machining, near dry machining, Titanium alloy, tool life, surface roughness, micro hardness, metallurgical alteration.