Papers by Keyword: Titanium Machining

Abstract: Machining of titanium and its alloys is still the subject of research and researchers’ interest despite some improvement in its machinability from several machining methods. This research presents performance of nitrogen gas in machining titanium. Machining of titanium is carried out on conventional turning center with triangular insert and holder according to ISO designation. Compressed nitrogen gas contained a cylindrical tank is supplied to the cutting zone via speciallydesigned valve that controls pressure and volume of nitrogen. The gas outlet pipe of diameter 2 mm is directed to just-above the tool rake face. During machining, the gas is supplied with high pressure so that the cutting zone receives an effective cooling as well as the chip will easily break. The effectiveness of this new cooling strategy is demonstrated by tool condition after machining, and also by comparing with performance of conventional coolant. The result is found to be excellent in terms of relative amount of tool wear. The cutting insert has surprisingly been almost intact when using nitrogen gas as coolant whereas tool wear at failure state has occurred with conventional coolant for the same machining parameters.

Abstract: The formation of shear localized chips in orthogonal machining of Ti-6Al-4V was investigated. The chips in different cutting velocities were collected and the structure of the adiabatic shear localization was examined by optical microscope and SEM after polishing and eroding. The serrated coefficient, serrated frequency and fibred coefficient were proposed in this paper to characterize the degree of serration and plastic shear flow of the chip quantitatively. Experimental results show that the width of the shear band decreased and the fibred coefficient of the shear band increased as cutting speed increased. The serrated and frequency, the serrated coefficient increased with the increase of cutting speed in the experimental range of cutting speeds.