Experimental Research On Chatter And Tools Wear In Cutting Titanium Alloys

Titanium alloys has been widely used in aerospace industry because of its excellent characteristics. However, it is difficult to machine due to its low thermal conductivity, low modulus of elasticity and high chemical activity. A great deal of improvements have been made on the research of cutting titanium alloys, including cutting performance, surface integrality, tool wear, tool life and so on. But most of those aren't analyzed systematically and mainly at low cutting speed. In this paper, one kind of PCD tool and two kinds of tungsten carbide tools were chosen on cutting Ti6A14V at four different cutting speeds. In order to provide a theoretical basis for the machining of titanium alloys, research on chatter, tool life and tool wear was carried out.Firstly, a comparative experiment was carried out between the vibration of YD15 and PCD tools. It indicated that the value of acceleration amplitude for both of the tools raised as the cutting speed increased. The amplitude value was low at the speeds of 60 and 75m/min for YD15 tool, but increased sharply as the speed was increased to 90m/min and the trend was maintained up to the speed of 105m/min. It was significant only at 105m/min in the case of PCD tool, comparing to other cutting speeds, but lower than YD15 tool at each of the four speeds.Secondly, the morphology of the chips and the impact of chatter on it were thoroughly studied. The results showed that the continuous chip was observed for YD15 tool at the speed of 60m/min and turned to serrated chips as the speed increased while serrated chips in the case of PCD tool for all of the speeds. When the value of acceleration amplitude enlarged obviously, the serrated teeth of the chips became scraggly or some smaller elements were found in one larger element. On the contrary, while the value of acceleration amplitude was low, it was continuous chip or the serrated teethes of chips were even, uniform and regular. The morphology of the chips could give an indication of the presence or absence of chatter during machining. A particular mode of vibration occurred once the serration frequency was close to any integer number of natural frequency of the tool.In the end, lives of the three tools were compared, and the wear morphology and wear mechanism were studied according to the experiment of tool wear. It was concluded that the dominant wear mechanisms of the two tungsten carbide tools were adhesion at low speed and adhesion, diffusion, oxidation at high speed. Notch wear generated by graphitization and chipping were found to be the main wear mechanisms for PCD tool. Compared with the two tungsten carbide tools, PCD tool had a longer life especially at high speed.