Experimental investigation on milling of hardened steel Cr12

Hardened steel Cr12 test piece with hardness HRC50 is designed with special shape by means of Buda method. The effect of cutting speed and feeding per tooth on chip deformation and shear angle can be investigated comprehensively. The shear angle increases significantly with the increasing of cutting speed. So that, chip deformation becomes less and less with the increasing of cutting speed. The cutting power becomes greater with increasing of cutting speed, cutting temperature rises, and then the friction coefficient between tool-chip becomes smaller, so the shear angle has a gradually increasing trend. The shear angle increases significantly with the increasing of feeding per tooth. As feeding rate increases, cutting force increases, cutting temperature rises, friction coefficient decreases, thus, the shear angle has the trend of increasing. The cutting force investigation has been done by means of multi-factor orthogonal test method with four factors and four levels. The calculation equations for cutting forces have been deduced by means of the mixed algorithm of least-square method fitting and Monte Carlo fitting. It follows from the significant test results of regression analysis of cutting force calculation equations and coefficients based on 99% confidence that the equations for cutting force calculation are of excellent significance. Cutting speed is minor factor to impact cutting forces. Feeding per tooth and axial depth of cut are the most important parameters to impact cutting forces.