Abstract
A cut-away sintered carbide tool for turning operations has been proposed and successfully employed to improve the machinability of a 18%Mn-18%Cr manganese steel (HB=241). Both the chip contact length on the rake face and the chip flow direction can be uniquely determined by the energy method when the restricted length is assumed to be proportional to the real uncut chip thickness in the direction of chip flow. The optimum contact length is found to be 1.25 times as large as the real feed, which is slightly wider than that in the two-dimensional machining. The predicted cutting forces, cutting temperature and tool wear are all in good agreement with experiments. The restriction of the contact length causes the cutting forces and the heat generation on the shear plane and at the tool-chip interface to reduce, leading to the decrease in tool temperature. As a result, the wear on the rake face of a P20 carbide tool is lessened by 10% in the dry turning of such a high-hardness metal.
