Cutting Power and Spindle Torque
Cutting horsepower, motor horsepower after drive efficiency.
Example
You enter
- Material removal rate (in3/min) 3
- Unit power (hp per in3/min) 1
- Spindle drive efficiency (%) 80
- Spindle speed (rpm) 800
You get
- Cutting horsepower 3 hp
- Motor horsepower needed 3.75 hp
- Spindle torque 19.7 lb-ft
Details, formula, and sources
Cutting horsepower, motor horsepower after drive efficiency, and spindle torque from the material removal rate and the specific cutting energy (unit power: about 1.0 carbon steel, 0.33 aluminum, 1.5 stainless/titanium) -- the stall / motor-size check before a heavy cut. The tool and machine govern the real draw.
Cutting horsepower = MRR (in3/min) x unit power (hp per in3/min); motor horsepower = cutting hp / (efficiency / 100); spindle torque (lb-ft) = 5252 x cutting hp / rpm.
Cutting power and spindle torque - first-principles specific-cutting-energy relation with Machinery's Handbook (Industrial Press) unit-power values, by name; the 5252 torque constant is universal.
The specific-cutting-energy arithmetic is public; the material removal rate, unit power, efficiency, and rpm are user-supplied.
Estimate. AHJ and licensed professional govern.
Field names used by the API: mrr_in3_min, unit_power_hp, efficiency_pct, rpm, cutting_hp, motor_hp, spindle_torque_lbft
- Unit power specific cutting energy, hp per in3/min: ~1.0 carbon steel, ~0.33 aluminum, ~1.5 stainless/titanium; default 1.0Machinery's Handbook
- Drive efficiency spindle drive efficiency; default 80%machine data