Effect of high pressure coolant jets in turning Ti-6Al-4V alloy with specialized designed nozzle

Abstract

In the rapid advancement of science and technology now-a-days the use of the metals and metallic alloys are more diversified as such the Titanium alloys are used significantly in the field of aerospace, biomedical and automotive industries because of it’s good strength to weight ratio and corrosion resistance. However it has been observed that, it is very difficult to machine the Titanium alloys due to their poor machining ability. Titanium alloys have low thermal conductivity, low elastic modulus, maintenance of high hardness at elevated temperature and high chemical reactivity with many cutting tools. All these factors result in rapid tool wear, low material removal rate (MRR) and degradation of surface integrity of machined parts.A number of experiments and investigations have been made by the several researchers to machine the titanium alloy Ti-6Al-4V in dry cutting condition .In dry cutting, absence of cutting fluid causes limitation in the cutting speed which may results in high temperature, rapid tool wear and degradation of work piece surface integrity. The cryogenic cooling maintains low surface temperature and pollution free environment but additional equipment and price of nitrogen gas make it costly. On the other hand, flood cooling and MQL is suitable at low cutting speed which gives low MRR and it is not environmental friendly as well. It is obvious that the applied coolant cannot enter the exact location of tool-work interface in flood cooling and MQL condition. To mitigate this problem, high pressure coolant (HPC) technique have been applied by many researchers by applying the HPC jet into the chip and tool work interface which allows high cutting speed and results better tool life and surface finish. However as on today very little work has been carried out by using of HPC jet into the chip and tool-work interface and principle cutting edge at a simultaneously. Considering the above facts the Ti-6Al-4V alloy is machined in a better way by using the HPC jet with a view to control the high cutting temperature, minimizing the cutting force, extend the tool life and improving the surface roughness. In this regard a HPC nozzle is developed which will be able to maintain uniform pressure and spray HPC jets at the chip-tool and work-tool interface simultaneously. It was observed that the specialized HPC nozzle for turning of Ti-6Al-4V alloycan bring forth better performance when compared with dry turning.