FORMULAS FOR CUTTING
CUTTING SPEED (vc)
- vc (SFM)
- :Cutting Speed
- Dm (inch)
- :Workpiece Diameter
- π (3.14)
- :Pi
- n (min-1)
- :Main Axis Spindle Speed
(Problem) :
What is the cutting speed when main axis spindle speed is 700 min-1and external diameter is Ø2" ?
(Answer):
Substitute π=3.14, Dm=2, n=700 into the formulae.
vc=π× Dm×n÷12=3.14×2×700÷12=366.33SFM
Cutting speed is 366.33SFM.
FEED(f)
- f (IPR)
- :Feed per Revolution
- I (inch/min)
- :Cutting Length per Min.
- n (min-1)
- :Main Axis Spindle Speed
(Problem):
What is the feed per revolution when main axis spindle speed is 500min-1 and cutting length per minute is 120 mm/min?
(Answer):
Substitute n=500, I=4.72 into the formulae.
f=I÷n=4.72÷500=.009IPR
The answer is .009IPR.
CUTTING TIME (Tc)
- Tc (min)
- :Cutting Time
- Im (inch)
- :Workpiece Length
- I (inch/min)
- :Cutting Length per Min.
(Problem):
What is the cutting time when 4inch workpiece is machined at 1000min-1 with feed= .008IPR ?
(Answer):
First, calculate the cutting length per min. from the feed and spindle speed.
I=f×n=.008×1000=8inch/min
Substitute the answer above into the formulae.
Tc=Im÷I=4÷8=0.5min
0.5x60=30(sec.)The answer is 30 sec.
THEORETICAL FINISHED SURFACE ROUGHNESS (h)
- h (μinch)
- :Finished Surface Roughness
- f (IPR)
- :Feed per Revolution
- Re (inch)
- :Insert Corner Radius
(Problem):
What is the theoretical finished surface roughness when the insert corner radius is .031inch and feed is .008 IPR ?
(Answer):
Substitute f=.008IPR,Re=.031 into the formulae.
h =(.008)2÷(8×.031)×10002=258μinch
The theoretical finished surface roughness is 258μinch.
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
(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
(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.
(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
(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.