On the correlation between surface quality and tool wear in micro-milling of pure copper

Micro-milling is a material removal - based manufacturing technique that allows fabrication of three-dimensional features in a direct manner, unlike photolithography which relies on expensive masks to print two-dimensional features onto a substrate. However, the inadequate surface quality of micro-milled features, which could be due to improper selection of process parameters and/or tool wear, can hamper the functionality of products. This is specially critical for soft materials such as commercially pure copper. To preserve the surface integrity of such materials, this study proposes a correlation between tool wear and surface quality when micro-milling commercially pure copper. The experiments included full-immersion cutting with 200 mu m micro-endmills with an axial depth of cut of 20 mu m. The variation of surface roughness and burr formation with wear progression is also studied. The surface quality was investigated on the basis of the surface roughness and burrs geometrical characteristics, as well as in terms of nano-hardness. For doing that, firstly, different micro-milling parameters, namely the feed per tooth and cutting speed, were applied to manufacture a series of slots on a pure copper workpiece. Then, the best and the worst conditions in terms of surface quality were adopted for the tool wear campaign to find the correlation between the tool wear and surface quality.