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Milling Cutters & End Mills
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Speeds, Feeds & Power Calcs
Table 4 - Speed, Feed and Power Calculations
| To find |
Having |
Procedure |
Formula |
Peripheral cutting
speed - V |
Cutter diameter , d
Rotational speed, N |
Multiply cutter diameter by rotational speed
and 0.262 |
V = 0.262 dN |
Rotational
speed - N |
Cutter diameter, d
Peripheral cutting speed, V |
Divide the product of 3.82 and cutting speed
by cutter diameter |
N = (3.82 V)/d |
| Feed per tooth - f |
Machine feed rate, F
Rotational speed, N
Number of teeth, I |
Divide machine feed rate by product of
rotational speed and number of teeth |
f = F/NT |
Machine feed
rate - F |
Feed per tooth, f
Rotational speed, N
Number of teeth, T |
Multiply feed per tooth by rotational speed and
number of teeth |
F = fNT |
Feed per
revolution - f |
Machine feed rate, F
Rotational speed, N |
Divide machine feed rate by rotational speed |
fr = F/N |
Cutting power
input - P |
Width of cut, W
Depth of cut, h
Machine feed rate, F
Workpiece material power constant, C |
Divide the product of width of cut, depth of
cut, and machine feed rate by the power
constant |
P = (WhF)/C |
Definition of Symbols and Measurement
| Quantity |
Symbol |
Measurement Unit |
| Cutting speed |
V |
Speed feet per minute, sfm |
| Rotational speed |
N |
Revolutions per minute, rpm |
| Cutter diameter |
d |
Inches |
| Feed per tooth |
f |
Inches per tooth, ipt |
| Machine feed rate |
F |
Inches per minute, ipm |
| Feed per revolution |
fr |
Inches per revolution, ipr |
| Cutting power input |
P |
Horsepower, hp |
| Power constant |
C |
Cubic inches per horsepower minute |
| Width of cut |
W |
Inches |
| Depth of cut |
h |
Inches |
| Number of teeth |
T |
- |
Power Constants for
Use with Table 4
Power constant values for various materials
are the number of cubic inches of metal per
minute capable of being removed per
horsepower input with 60% power efficiency
at the spindle nose and a 25% allowance for
cutter dulling.
| Work Material |
C (Constant) |
| Magnesium | 4.0 |
| Aluminum | 4.0 |
| Copper | 2.0 |
| Brass | 2.5 |
| Bronze | 2.0 |
| Malleable Iron | 1.0 |
| CastIron -- | |
| Ferrite | 1.5 |
| Pearlitic | 1.0 |
| Chilled | .6 |
| Steel -- | |
| Up to 150 Brinell | .7 |
| 300 Brinell | .6 |
| 400 Brinell | .5 |
| 500 Brinell | .4 |
| Stainless Steel -- | |
| Free Machining | 1.0 |
| Other | .6 |
| Titanium -- | |
| Under 100,000 psi | .8 |
| 100,000 - 135,000 psi | .6 |
| 135,000 psi & over | .4 |
| High Tensile Alloys -- | |
| 180,000 - 220,000 psi | .5 |
| 220,000 - 260,000 psi | .4 |
| 260,000 - 300,000 psi | .3 |
| High Temperature Alloys -- | |
| Ferritic Low Alloys | .6 |
| Austenitic Alloys | .5 |
| Nickel Base Alloys | .4 |
| Cobalt Base Alloys | .4 |
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