Calculation formula of hole machining
.Cutting speed( vc )
: Cutting speed
D1 (mm)
: Drill bit diameter
: Circumference ratio
n (min-1)
: Rotation speed of spindle
* Dividing by 1000 is to convert mm into m
(Example) rotation speed of spindle is 1350min-1 and drill bit diameter is2,
calculate cutting speed.
(Answer) integrate=3.14D1=12N=1350 in the formula;

Therefore, derive that cutting speed is 50.9m/min
.Feed of spindle( vf ):
vf=frn (mm/min) vf(mm/m)
: Feeding speed (Z-axis) of spindle
fr (mm/rev)
: Feed per revolutions
n (min-1)
: Rotation speed of spindle
(Example)Feed per revolution is 0.2mm/rev and rotation speed is 1350min-1,calculate feeding speed of spindle.
(Answer) integrate=3.14D1=12N=1350 in the formula;
vf=frn = 0.2 1350=270 mm/min
From here, it is derived that feeding distance of spindle is 270mm/min
.Hole machining time( Tc )
: Machining time
n (min-1)
: Rotation speed of spindle
: Depth of drilled holes
: Feed per revolution
: Number of hole
(Example) Drill bit a hole of15 and 30mm deep in SCM440 steel,
cutting speed is 50m/min, and feed per revolution is 0.15mm/rev.
Calculate cutting time.

(Answer) rotation speed of spindle
11.3 Seconds can finished.