A Study on Micro-Milling of Aluminium 6061 and Copper With Respect to Cutting Forces, Surface Roughness and Burr Formation

In the present study, micro-milling of aluminium 6061 alloy and copper was undertaken. TiAlN coated two-flute flat end milling cutters of 0.5 mm diameter were used for conducting micro-channel milling experiments with minimum quantity lubrication (MQL) as the cutting environment. The effect of process parameters namely cutting velocity (v_c) and feed per flute (f_z) on the cutting forces, surface roughness and burr width are reported. RMS values of longitudinal feed force (F_X), transverse cutting force (F_Y) and vertical thrust force (F_Z) were measured and the maximum values for Al 6061 are 0.33 N, 0.16 N and 0.21 N respectively, and the same for copper are measured to be 0.11 N, 0.17 N and 0.22 N respectively. Average surface roughness along the milling direction (R_a) at the bottom surface of the micro-channel was measured. Smoother surfaces were generated at lower feed per flute in both the materials. R_a is found to be varying from 28.2 nm to 86.9 nm for Al 6061, and for copper, the range is from 4.9 nm to 32.7 nm. SEM images of the micro-channels were analysed and top burr width was measured in both up-milling and down-milling directions. Higher feed per flute produced smaller burrs in both up-milling and down-milling directions. Maximum burr width for Al 6061 is measured to be 12.86 μm and 15.28 μm in up-milling and down-milling direction respectively, and for copper, the same are measured to be 12.84 μm and 20.46 μm respectively.