Development of a new high-pressure cooling system for machining of difficulut-to-machine materials

In recent years, titanium alloys and nickel alloys have become eminent for making aeronautic and astronautic parts. Since both nickel and titanium alloys have a very small thermal conductivity, the being used tool will suffer from huge damage by heat generated during the grinding process. Therefore, there is a requirement for a durable tool with excellent cooling capacity. In this research, the technology regarding the new forced cooling using with high-pressure coolant for machining difficult-to-machine material was developed and evaluated. A through-hole in the near the tip on the rake face of the turning tool is firstly machined by electrical discharge machining. High-pressure coolant was then supplied to the turning tool from the hole on the bottom of the tool. Several values of pressure were tried in many experiments. It is concluded from the results that; (1) a new forced cooling method in the form of drilling a hole at the tip of the tool from which supply high-pressure coolant, a tool temperature decrease and a tool-life prolongation could be achieved, (2) the technology could effectively cool near the tip of turning tool, (3) the chip was effectively broken by the high pressure, (4) It was confirmed that the tool cutting edge condition was stabilized, the surface roughness of the machined workpieces was improved, the tool hardness was maintained and the tool-life was prolonged due to the cooling effect of the devised tool.