An experimental investigation on effects of minimum quantity lubrication oil supply rate in high-speed end milling of Ti–6Al–4V

Abstract

Minimum quantity lubrication is an alternative to realize machining titanium alloys both economically and ecologically. In order to apply minimum quantity lubrication more efficiently, an investigate of the effects of the operating parameters involving oil supply, compressed air supply, and nozzle orientation is required. This article focuses on the oil supply rate of minimum quantity lubrication and aims to identify the effects of the minimum quantity lubrication applications with different oil supply rates in high-speed end milling of Ti–6Al–4V. The experiments were conducted by adjusting the oil supply rate from 2 ml/h to 14 ml/h, and cutting force, surface roughness, tool wear and failure mode, and tool wear mechanism were discussed. The results indicate that the increase of the oil supply rate effectively reduces cutting force and surface roughness, but after 10 ml/h the reduction is no longer significant. Increasing oil supply has growing penetration depth along the cutting edge, and by increasing the oil supply rate the length of the chipping edge can be notably reduced. For an insufficient oil supply rate (2 ml/h∼10 ml/h) chipping on the cutting edge introduced by diffusion wear is the main tool rejection reason, but at 14 ml/h no diffusion wear is found and the uniform flank wear is dominant, owing to reduced cutting temperature.