Application of digital image processing technique in the microstructure analysis and the machinability investigation

OBRABOTKAMETALLOV Том 23 № 4 2021 TECHNOLOGY Results and Discussion An important indicator of machinability in the case of solid ferrous metal is hardness. The microstruc- ture is a more fundamental indicator in the case of gray cast iron [22]. In 1956, Moore and Lord investigated the effect of microstructure on the machinability index and devel- oped an equation speci fi cally intended for gray cast iron [23]. 195, 5 1, 26 11, 7 1, 26 , vp vg g M V V S = - ⋅ + ⋅ + ⋅ Where V vp and V vg refer to the volume fractions of pearlite and graphite in the microstructure, respectively. S g is determined by the average size of the graphite fl akes in microns. Table 3 indicates the relationship between machinability as an output parameter and microstructural parameters as input parameters. Figure 3 shows the variation of the machinability at the different depths from the mould-metal interface. Ta b l e 3 Machinability values vs input parameters Depth from surface Volume fraction of pearlite, V vp Volume fraction of Graphite, V vg Average size of graphite fl akes in mm, S g Machinability Index, M 0.5 65.73 15.44 3.559 304.0129 1.0 44.41 12.43 5.315 300.9336 1.5 49.98 12.43 5.680 295.0068 2.0 52.02 9.70 5.249 259.2040 2.5 67.30 13.56 5.091 284.6398 3.0 66.51 14.77 6.055 302.6858 3.5 57.57 15.16 5.175 317.5972 Fig. 3. Machinability at different depth from M-M interface Conclusion The current study examines the workability index of grey cast iron at different depths from the surface. The available value of machinability is found maximum at a depth close to 3.5 mm. Volume fraction of pearlite, graphite, and average graphite fl akes are considered as an input function for machinability. The higher value of graphite fl akes dominates the machinability index value.