For machining a cast iron workpiece by a high speed steel tool, the average cutting speed is

For machining a cast iron workpiece by a high speed steel tool, the a

1.	For machining a cast iron workpiece by a high speed steel tool, the average cutting speed is
A.	10 m/min
B.	15 m/min
C.	22 m/min
D.	30 m/min
Answer» D. 30 m/min