FORMULAS FOR MILLING
CUTTING SPEED (vc)

*Divide by 1,000 to change to m from mm.
- vc (m/min)
- :Cutting Speed
- D1 (mm)
- :Cutter Diameter
- π (3.14)
- :Pi
- n (min-1)
- :Main Axis Spindle Speed
(Example)
What is the cutting speed when main axis revolution number is 350 min-1,
and cutter diameter is ø125?
(Answer)
Substituting p=3.14, D=125 and n=350 into the
formula.
vc=(p×D×n)÷1000=(3.14×125×350)÷1000
=137.4(m/min)
The cutting speed is 137.4 m/min.
FEED PER TOOTH (fz)

*Divide by 1,000 to change to m from mm.
- fz(mm/tooth)
- :Feed per Tooth
- vf (mm/min)
- :Table Feed per Min
- z
- :Insert Number
- n (min-1)
- :Main Axis Spindle Speed (Feed per Revolution f=z×fz)
(Example)
The rotation speed of the main spindle is 500 min-1, the number of
teeth is ten, and the table feed is 500 mm/min. The feed per tooth can be calculated
as follows...
(Answer)
Substituting these values into the formula
fz=vf÷(z×n)=500÷(10×500)=0.1mm/tooth
Thus the feed per tooth is approximately 0.1 mm/tooth.
- vf (mm/min)
- :Table Feed per Min.
- fz (mm/tooth)
- :Feed per Tooth
- z
- :Insert Number
- n (min-1)
- :Main Axis Spindle Speed
(Example)
What is the table feed when feed per tooth is 0.1mm/tooth, insert number is 10,and
spindle speed is 500 min-1?
(Answer)
Substitute the above figures into the formula.
vf=fz×z×n=0.1×10×500=500mm/min
The table feed is 500 mm/min.
CUTTING TIME (Tc)
- Tc (min)
- :Cutting Time
- vf (mm/min)
- :Table Feed per Min.
- L (mm)
- :Total Table Feed Length (Workpiece Length (I) + Cutter Diameter (D1))
(Example)
What is the cutting time required for finishing 100mm width and 300mm length surface
of cast iron (JIS FC200) block when cutter diameter is ø200,insert number
is 16,cutting speed is 125m/min,and feed per tooth is 0.25mm (Spindle speed 200
min-1)?
(Answer)
(Answer)
Calculate table feed per minute.
vf=0.25×16×200=800mm/min
Calculate total table feed length.
L=300+200=500mm
Substitute the above answers into the formula.
Tc=500÷800=0.625(min)
0.625×60=37.5(sec)
The answer is 37.5 seconds.