Performance evaluation of DLC and NCD coatings in micro-milling of Al7075-T6 alloy

The main problem in machining of aluminum alloys is the adhesion of chips to the cutting tool. In micro milling, chip adhesion causes a decrease in surface quality and contributes to micro burr formation. There are several ways to minimize chip adhesion, one of which is to coat the tool with the appropriate material. Carbon-based coatings are coating materials that can minimize chip adhesion. In this study, the performances of Diamond -Like Carbon (DLC) and Nano-Crystalline Diamond (NCD) coating materials in the micro-milling process of Al7075-T6 alloy were investigated in all aspects. The tests are performed under dry cutting conditions using various cutting parameters. Experimental results show that DLC and NCD coated tools produce approximately 20 % and 40 % lower forces, respectively. For fz < 0.5 mu m/tooth, no decisive influence of the coating material on the cutting forces is observed. For fz < 0.5 mu m/tooth, surface roughness and burr width increase significantly in uncoated and NCD coated tools due to size effect. A strong size effect was observed at feed values less than approximately 36 % of the tool edge radius in terms of surface roughness and <18 % of the tool edge radius in terms of burr width.