Face Turning

Q.

Common Data:
A disc of $200mm$ outer and $80mm$ inner diameter is faced at a feed of $0.1mm/rev$ with a depth of cut of $1mm$. The facing operation is undertaken at a constant cutting speed of $90m/min$ in a CNC lathe The main (tangential) cutting force is $200N$

Assuming approach and over-travel of the cutting tool to be zero, the machining time in min is

1. $2.93$
2. $5.86$
3. $6.66$
4. $13.33$

Q.

Common Data:
A disc of $200mm$ outer and $80mm$ inner diameter is faced at a feed of $0.1mm/rev$ with a depth of cut of $1mm$. The facing operation is undertaken at a constant cutting speed of $90m/min$ in a CNC lathe The main (tangential) cutting force is $200N$

Neglecting the contribution of the feed force towards cutting power, the specific cutting energy in $J/m{m}^3$ is

1. $0.2$
2. $2$
3. $200$
4. $2000$