Non-free cutting and its degree of freedom confinement

Plunge-turning processes of round-edged cutters is analyzed and its cutting force modeled in the light of a general theory of non-free cutting developed by the authors. In this study the whole cutting tool is treated as a combination of a series of Elementary Cutting Tools (ECTs). Due to the non-linearity of chip-ejection interference among all the ECTs the total cutting force of the whole cutter, however, cannot be calculated by simply superposing the incremental cutting forces generated by all the ECTs. A Non-Linear Synthesis Method (NLSM) is therefore suggested for modeling this non-free cutting force. The main feature of the method is that the chip-ejection interference is under consideration and modeled on the basis of the Principle of Minimum Energy (PME). Good agreement between the predicted and measured main cutting forces is identified. Furthermore, a Coefficient of Non-Free Cutting (CNFC) is applied to quantitatively indicate the strength of chip-ejection interference among the ECTs and the degree of freedom confinement of the cutting process.