Experimental study on a novel minimization method of top burr formation in micro-end milling of Ti-6Al-4V

Abstract

This paper investigates the top burr formation mechanism and minimization method in the micro-end milling of titanium alloy Ti-6Al-4V. The top burr formation procedure has been systematically deduced to reveal the reason for the occurrence of a top burr considering the cutting trajectory of the micro-milling tool, the chip thickness h, and the variation in the micro-milling force Fp. A new method to minimize the top burr in micro-end milling of Ti-6Al-4V is proposed in this study: resin coating is fabricated to control and reduce the top burr size by absorbing the Wp energy. A series of micro-end milling experiments were performed to test this new method. The experimental measurement results prove that the method in this study significantly reduces the top burr size in the micro-end milling of Ti-6Al-4V. Two different top burr formation modes during micro-end milling have been found, and the effect of the minimum chip thickness hm on the top burr size is revealed. When h is below hm, large squeezing and tearing result in a poor surface and large top burrs; when h is above hm, the top burr size suddenly decreases. The relations between the top burr size variation bl, bw, and the cutting-force work Wp are determined and discussed. Based on the new technology that this study develops, a series of micro-milling surfaces with the smallest top burr size to date worldwide are achieved. The knowledge obtained from this study is expected to be an important contribution to top burr minimization in micro-machining.