A Static Model of Chip Formation in Microscale Milling

This paper discusses the development of an enhanced, static model of chip formation in micromilling processes that is able to describe the intermittency of the chip formation observed at low feeds per tooth due to the dominance of the minimum chip thickness effect. Experimental analyses demonstrate the validity of the proposed model by verifying the level of periodicity in the cutting forces present at various feeds per tooth. A key finding of this study is the identification of a local maximum in the radial thrust forces in the micromilling process during the noncutting regime, at feeds per tooth that are of the order of the minimum chip thickness. To overcome the challenges in the direct measurement of the minimum chip thickness, this paper presents a method for estimating the minimum chip thickness of various combinations of tools and workpiece materials based on easily attainable cutting-force data. A discussion on the selection of process parameters to avoid intermittent chip formation is also presented.