In order to compensate the effect of tool wear on the
surface roughness of the machined test parts, initially the
investigations was limited to the very first section of the
machined path. As shown in Fig. 3, the surface
roughness measurements revealed that the average
arithmetic surface roughness (Ra) has been reduced from
0.21μm to 0.14μm resulting in more than 33% reduction
in surface roughness. A similar trend has been observed
for ISO Rz value of the surface roughness where the
introduction of cryogenic cooling has reduced the ISO
Rz value from 2.25μ to 1.34 resulting in 40% reduction.
Although cryogenic cooling has improved the surface
roughness of the machined parts at the very first section
of the machining path, significantly higher values of
surface roughness was measured for the rest of the path
as compared to dry machining. This indicated the
inverse effect of cryogenic cooling on the tool life which
has a direct effect on the surface roughness.