Machining Response and Damage Evolution of Amorphous Carbon Coated Tools in High-Speed Micromilling of Ti–6Al–4V

Abstract

Micromilling process is widely used to create complex 3D miniature products due to its flexibility and its ability to process difficult-to-cut material like Titanium alloys. High rotational speeds are used to overcome the limited flexural stiffness of the tool but the cutting zone temperatures rise due to the high rotational speeds. In addition to this, friction between the tool workpiece and tool chip also plays a major role in the temperature rise. The friction and temperature affect the cutting forces, tool life and stability of the process. To reduce the friction and heat generation, nanostructured solid lubricant coatings can be used. This study is focused on characterizing the effect of amorphous carbon (WC/a-C) coating on the micromachining response during high-speed micromilling of Ti–6Al–4V. A decrease in cutting forces for coated tools is observed for lower feed. A comprehensive tool coating damage assessment has been done in terms of debonding area on flank and rake faces. An increase in debonding area has been observed with lengths of cut but at a feed/flute of 4 μm, tool breakage occurs after a machining length of 60 mm.