MITSUBISHI MATERIALS CORPORATION
BACK


FORMULAE FOR DRILLING

¨CUTTING SPEED (vc)

Calculate
*Unit transformation (from "mm" to "m")

vc (m/min) : Cutting Speed
p (3.14) : Circular Constant
D1 (mm) : Drill Diameter
n (min-1) : Rotational Speed of the Main Spindle
Input the values
n (min-1)
 D1(mm)
vc (m/min)
Graphic Image (Problem)
What is the cutting speed when main axis spindle speed is 1350min-1 and drill diameter is 12mm ?
(Answer)
Substitute p =3.14, D1=12,n=1350 into the formulae

vc =(p ×D1×n)÷1000 =(3.14×12×1350)÷1000=50.9m/min

The cutting speed is 50.9m/min.
¨FEED OF THE MAIN SPINDLE (vf)

Calculate

vf (mm/min) : Feed Speed of the Main Spindle(Z axis)
fr (mm/rev) : Feed per Revolution
n (min-1) : Rotational Speed of the Main Spindle

Input the values
fr (mm/rev)
 n(min-1)
vf (mm/min)
Graphic Image (Problem)
What is the spindle feed (vf) when feed per revolution is 0.2mm/rev and main axis spindle speed is 1350min-1?
(Answer)
Substitute fr=0.2, n=1350 into the formulae

vf = fr×n = 0.2×1350 = 270mm/min

The spindle feed is 270mm/min.
¨DRILLING TIME (Tc)

Calculate

Tc (min) : Drilling Time
n (min-1) : Spindle Speed
ld (mm) : Hole Depth
fr (mm/rev) : Feed per Revolution
i : Number of Holes
Input the values
ld (mm)
i
n (min-1)
fr (mm/rev)

Tc (min)
second (s)
Graphic Image (Problem)
What is the drilling time required for drilling a 30mm length hole in alloy steel at a cutting speed of 50m/min and feed 0.15mm/rev ?
(Answer)
Spindle Speed
n=(50×1000)÷(15×3.14)=1061.57min-1

Tc=(30×1)÷(1061.57×0.15)=0.188

=0.188×60=11.3sec.