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# FORMULAE FOR CUTTING POWER

CUTTING SPEED (Pc) *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) (Problem)
What is the cutting speed when main axis spindle speed is 700min-1 and external diameter is Ø50? Substitute π=3.14, Dm=50, n=700 into the formula.
(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 110 m/min.

FEED (f) 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) (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 0.24 mm/rev.

CUTTING TIME (Tc) 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) 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) (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. TOP BACK