Formula for Turning

Cutting Speed (vc)
FORMULAE
※Divide by 1000 to change to m from mm.
vc (m/min) : Cutting Speed
Dm (mm) : Workpiece Diameter
π (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)


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(Problem)
What is the cutting speed when main axis spindle speed is 700min-1and external diameter is Φ50 ?
(Answer)
Substitute π=3.14, Dm=50, n=700 into the formula.
vc=(π×Dm×n)÷1000=(3.14×50×700)÷1000
=110(m/min)

Cutting speed is 110m/min.


Feed (f)
FORMULAE
f (mm/rev) : Feed per Revolution
I (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)


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(Problem)
What is the feed per revolution when main axis spindle speed is 500min-1 and cutting length per minute is 120mm/min ?
(Answer)
Substitute n=500, I=120 into the formula.
f=l÷n=120÷500=0.24(mm/rev)
The answer is 0.24mm/rev.


Cutting time (Tc)
FORMULAE
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 1000min-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 formula.
Tc=lm÷l=100÷200=0.5(min)0.5×60=30(sec)
The answer is 30 sec.

Theoretical finished surface roughness (h)
FORMULAE
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)

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(Problem)
What is the theoretical finished surface roughness when the insert corner radius is 0.8mm and feed is 0.2mm/rev ?
(Answer)
Substitute f=0.2mm/rev, RE=0.8 into the formula.
h=f2÷(8×Re)×1000=0.22÷(8×0.8)×1000=6.25µm
The theoretical finished surface roughness is 6µm.

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