MITSUBISHI MATERIALS CORPORATION
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FORMULAS FOR DRILLING

CUTTING SPEED (vc)
Formula

vc (SFM) : Cutting Speed
D1 (inch) : Drill Diameter
π (3.14) : Circular Constant
n (min-1) : Rotational Speed of the Main Spindle
Check the item you want to calculate, input values in the two boxes, and then press the Calculate button.
n (min-1)
D1 (inch)
vc (SFM)

*Unit transformation (from "mm" to "m")
image(Problem) :
What is the cutting speed when main axis spindle speed is 1350min-1 and drill diameter is .500inch ?

(Answer):
Substitute π=3.14, D1=.500inch, n=1350 into the formulae
vc=π× D1×n÷12=3.14×.500×1350÷12=176.6SFM

The cutting speed is176.6SFM.


FEED OF THE MAIN SPINDLE (vf)
Formula vf (inch/min) : Feed Speed of the Main Spindle (Z axis)
fr(IPR): Feed per Revolution
n (min-1): Rotational Speed of the Main Spindle
Input the values
fr
n (min-1)

Vf (inch/min)

image(Problem):
What is the spindle feed (vf) when feed per revolution is .008IPR and main axis spindle speed is 1350min-1?

(Answer):
Substitute fr=.008, n=1350 into the formulae
vf = fr×n = .008×1350 = 10.8inch/min
The spindle feed is 10.8inch/min.

DRILLING TIME (Tc)
Formula Tc (min) : Drilling Time
n (min-1) : Spindle Speed
ld (inch) : Hole Depth
fr (IPR) : Feed per Revolution
i : Number of Holes
Input the values
n (min-1)
Id
i (inch)
fr (IPR)

Tc(min)
second (s)
image(Problem):
What is the drilling time required for drilling a 1.2inch length hole in alloy steel at a cutting speed of 165SFM and feed .006IPR ?

(Answer):
Spindle Speed n =(165×12) ÷ (.59×3.14) = 1068.8min-1

Tc =(1.2×1)÷ (1068.8×.006) = .187
= .187×60≒11.2 sec