
310 Fundamentals of Machining Processes
The volumetric removal rate from the workpiece due to the hammering
mechanism VRR
h
can be evaluated as
VRRkkk
aF
kj
h
tav
w
=
+
123
4
21σπ ()
j
==
t
w
σ
The computational results of Jain (2004) showed that
where
h
h
is the depth of penetration due to grit hammering in mm
f
r
is the frequency of tool oscillation in 1/s
σ
t
is the mean stress acting upon the tool in N/mm
2
ρ
a
is the density of abrasive grits in g/cm
3
σ
w
is the mean stress acting upon workpiece surface in N/mm
2
F
av
is the mean force on the grit in N
10.1.2 Solved Example
Calculate the USM time required for a hole of diameter 6 mm in tungsten ...