Drilling:

D = 10 mm

Cutting speed V=18 m/min

Spindle speed = $\frac{320 V}{D}$ = 576 rpm

Assume, Feed = 0.2 mm/rev

$\quad$ = 0.2 $\times$ mm/rev = 0.2 $\times$576

$\quad$ = 115 mm/min

Milling:

D = 6 mm

Cutting speed V=15 m/min

Spindle speed =$\frac{320 V}{D}$ = 800 rpm …