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 |
