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K. Balaji and N. Yuvaraj
a vital role in affecting surface roughness. Lower stand-off increases the velocity
of the abrasives which makes strong erosion in the die steel. It is concluded that
spherical shaped abrasives are not suitable for machining die steel.
3.2 Circularity
Table 3 shows the Circularity values for the various machining conditions with
different stand-off distances. The comparison of circularity values is shown in Fig. 4.
This measurement has been taken at three regions of the machined hole namely top,
middle, and bottom. From that, average circularity was taken for the experimental
analysis. The results indicate that SiC abrasive has produced the least circularity in
the hole at a stand-off distance of 5 mm. These combined parameter settings allow
Table 3 Circularity of drilled holes
S. No.
Abrasive
Standoff
distance
(mm)
Top
(mm)
Middle
(mm)
Bottom
(mm)
Circularity
(mm)
1
Silicon carbide
5
0.027
0.040
0.038
0.035
2
3
0.081
0.094
0.182
0.119
3
1
0.110
0.172
0.149
0.143
4
Garnet
5
0.098
0.127
0.129
0.118
5
3
0.087
0.107
0.142
0.112
6
1
0.334
0.378
0.461
0.391
7
Garnet-silicon
carbide (60:40)
5
0.092
0.113
0.142
0.115
8
3
0.083
0.091
0.076
0.083
9
1
0.327
0.359
0.438
0.374
Fig. 4 Circularity values of AWJ drilled holes