Spindle Power.
Determines the required spindle power (Horsepower and Kilowatts) to execute a cut based on the Material Removal Rate (MRR) and the material's specific cutting energy (Unit Power).
Power Requirement
The Mathematics
Spindle power calculation prevents stalling the machine or catastrophic tool failure caused by exceeding available torque.
Material Removal Rate (MRR)
MRR (in³/min) = RDOC × ADOC × IPM
The volume of material removed per minute.
Required Power
HP = (MRR × Unit Power) / Efficiency Factor
Unit power is the specific cutting energy—the horsepower required to remove one cubic inch of a specific material in one minute. This value varies wildly from 0.3 for aluminum to over 1.4 for nickel-based superalloys.
Conversion
kW = HP × 0.7457
Crucial Note on Torque
Power (HP) is a function of Torque and RPM. A 20 HP spindle running at 10,000 RPM produces very little torque compared to a 20 HP spindle geared down to 1,000 RPM. Always verify the required torque against your machine's torque-power curve chart.