Experimental Study on the Surface Integrity and Chip Formation in the Micro Cutting Process

The micro cutting mechanism is very different from the macro cutting process, where the workpiece is not considered as isotropic solid. Hence the effect of microstructure on the micro cutting mechanism needs to be further studied. In this paper, pure copper with two different grain sizes was machined by the natural single crystal diamond cutting tool, in order to study the effect of microstructure on the machined surface integrity and chip formation, during the micro cutting process. According to the experimental results, the hardness of original pure copper was higher than the annealed pure copper due to the grain boundary strengthening. The grain boundary can be found in the machined surface of annealed pure copper. As for original pure copper, the grain boundary is absent and the surface had only traces of tool path. In the grain boundary, the height of peak-valley is larger than that inside grain. The following indicates that the reduction of grain size will reduce the effect of microstructure on the surface integrity in the micro cutting process. With the decreasing of feed rate, cutting chip's shape changed from continuous to segmented at the same depth of cut (DOC) in both original and annealed pure copper. The chip of annealed pure copper is more segmented than the original copper at some cutting conditions.