Influence of Different Abrasives Mixtures on Abrasive Water …
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3 Results and Discussion
3.1 Surface Roughness
Table 2 shows the Ra values for the various machining conditions with different standoff distances. The comparison of Ra values is shown in Fig. 3. From the results, it is
noticed that lowest surface roughness was found at SiC with a stand-off distance of
1 mm was employed. These results happened due to the impingement of hard abrasives which erode the material with uniform amount of material removal rate. Lower
surface roughness was also observed in 60:40 abrasives and is found to be 1.56 µm.
The combined action of both angular and spherical shaped grains in 60:40 mixtures
which results in the good surface finish when a stand-off distance of 1 mm was used.
In contrast, garnet abrasive shows a higher roughness due to the major involvement
of spherical shaped abrasives. Also, it is observed that lower stand-off distance plays
Table 2 Ra of drilled holes
S. No.
Abrasive
Standoff distance
Ra, µm
1
Silicon carbide
5
2
2
3
1.98
3
1
1.23
4
Garnet
5
2.28
5
3
2.20
6
1
1.73
7
Garnet-silicon carbide (60:40)
5
2.23
8
3
1.98
9
1
1.56
0
0.5
1
1.5
2
2.5
Roughness, μm
Experimental Conditions
Fig. 3 Surface roughness of AWJ drilled holes