Direction: A low carbon steel bar of 147 mm diameter with a length of 630 mm is being turned with uncoated carbide insert. The observed tool lives are 24 min and 12 min for cutting velocities of 90 m/min and 120 m/min respectively. The feed and depth of cut are 0.2 mm/ rev and 2 mm respectively. Use the unmachined diameter to calculate the cutting velocity.
-
When tool life is 20 min, the cutting velocity in m/min is
-
- 87
- 97
- 107
- 114
Correct Option: B
Here, D = 147 mm, L = 630 mm,
f = .2 mm/rev,
d = 2 mm
Tool life equation,
VTn = constant
Now, V1T1n = V2T2n
Here, n = .415
∴ VTn = V1T1n
⇒ V =97.07 m/min
