MITSUBISHI MATERIALS CORPORATION
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FORMULAE FOR TURNING

¨CUTTING SPEED (vc)
Formula
* Divide by 1,000 to change to m from mm.

vc (m/min) : Cutting speed
Dm (mm) : Workpiece diameter
p (3.14) : Pi
n (min-1) : Main Axis Spindle Speed
Check the item you want to calculate, input values in the two boxes, and then press the Calculate button.
n (min-1)
Dm (mm)
vc (m/min)
Graphic Image (Problem)
What is the cutting speed when main axis spindle speed is 700 min-1, and external diameter is ø50?
(Answer)
Substitute p =3.14, Dm=50 n=700 into the formulae.

vc=(p×Dm×n)÷1000=(3.14×50×700)÷1000
=110 (m/min)

Cutting speed is 110 m/min.
¨ FEED (f)
Formula

f (mm/rev.) : Feed per revolution
l (mm/min) : Cutting length per Min
n (min-1) : Main Axis Spindle Speed
Check the item you want to calculate, input values in the two boxes, and then press the Calculate button.
l (mm/min)
n (min-1)
f (mm/rev)
Graphic Image (Problem)
What is the feed per revolution when main axis spindle speed is 500 min-1, and cutting length per minute is 120 mm/min ?
(Answer)
Substitute n=500, l=120 into the formulae.

f=l÷n=120÷500=0.24 (mm/rev)

The answer is 0.24 mm/rev.
¨CUTTING TIME (Tc)
Formula

Tc (min.) : Cutting Time
lm (mm) : Workpiece Length
l (mm/min) : Cutting Length per Min.
Input the values
 lm (mm)
l (mm/min)
Tc (min)
second (s)

(Problem)
What is the cutting time when 100mm workpiece is machined at 1,000min-1, with feed=0.2mm/rev?

(Answer)
First, calculate the cutting length per min. from the feed and spindle speed.

l=f×n=0.2×1000=200(mm/min)
Substitute the answer above into the formulae.

Tc=lm÷l=100÷200=0.5(min)

0.5×60=30(sec.) The answer is 30 seconds.
¨THEORETICAL FINISHED SURFACE ROUGHNESS (h)
Formula

h (µm) : Finished Surface Roughness
f (mm/rev.) : Feed per Revolution
Re (mm) : Insert Corner Radius
Input the values
f (mm/rev)
Re (mm)

h (µm)
Graphic Image (Problem)
What is the theoretical finished surface roughness when the insert corner radius is 0.8mm and feed is 0.2 mm/rev ?
(Answer)
Substitute f=0.2 mm/rev, R=0.8 into the formulae.

h=f2÷(8×Re)×1000=0.22÷(8×0.8)×1000=6.25µm
The theoretical finished surface roughness is 6 µm.