Determination of the wear coefficient of tungsten carbide by a turning operation

Turning operation was carried out, by using tungsten carbide inserts and a CNC lathe on low carbon and medium carbon steels, to determine the wear coefficient of tungsten carbide. The nominal (starting) workpiece diameter was 118 mm and the cutting speeds used were 70, 100, 130 and 160 m/min. The thrust and turning forces acting on the insert were measured from a force dynamometer. The turning distance was obtained from the diameter of the workpiece and its rotational speed. Calculations were made on the flank and crater wear volumes using an OMIS machine. The average wear coefficient of tungsten carbide was found to be 10×10−8. This value was obtained by averaging the wear coefficient values determined from the flank wear on turning both low and medium carbon steels; as well as from a statistical analysis of the wear coefficient values obtained between a turning temperature of 453 and 664°C. As compared with the average value of 106×10−8 obtained from the moving pin-on-disc test conducted earlier, it is lower by about one order of magnitude. It is suggested that the high turning temperature at the tool-chip interface may have lowered the hardness of the work materials during the turning operation to give the lower wear coefficient values.