Force model for chip breaking in orthogonal machining

The present tendency towards increased automation of metal cutting operations has resulted in a great emphasis on the monitoring and prediction of chip breakability. In order to better understand the mechanism of chip breaking, it is first necessary to have quantitative information about all the forces acting on the chip, within a chip breaking cycle. Conventional cutting force models do not permit such a study, since they assume a continuous mode of chip formation, where the contact action of the free-end of the chip is ignored in all analyses. The new cutting force model proposed in this work is applicable to the problem of two-dimensional chip breaking in orthogonal machining. A methodology to determine the forces acting on the chip, including the contact force developed due to the free-end of the chip touching the workpiece, has been formulated using both experimental and estimation techniques. Orthogonal cutting tests were conducted to obtain two dimensional chip breaking. The experimentally obtained cutting forces show a good correlation with the estimated cutting forces. Using the proposed methodology, the forces acting on the chip were determined. Results show that these forces, while exhibiting cyclic variations, enable the identification of the chip breaking event.