The Deformation Process in Metal-Cutting

An analysis of the orthogonal chip process for a strain-hardening material is presented together with a qualitative evaluation of the effects of temperature increases and of flank rubbing. An expression is derived for the average stress on planes through the tool point ahead of the shear plane. The authors postulate that the strain-hardening requires that a stress-reinforcing phenomenon be present and that this requires the shear to take place in a region of increasing stress. The rate of increase required is postulated to depend on the final strain imparted to the chip. Data from the literature are presented to support this view. The conclusion is drawn that the strain imparted to the chip is a measure of the deviation of the shear angle from the Merchant minimum-energy condition.