KEVOS® MAKEOS · Manufacturing
Spade Drilling Power and Thrust
What power and thrust does this spade drilling operation need?
Power at the cutter and at the motor, and the thrust force, for spade drilling by the handbook formulas from drill diameter, feed, speed and the unit power of the work material, with an allowance for tool wear.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Drill diameter | mm | Diameter of the spade drill. |
| Feed per revolution | mm/rev | Feed per revolution. |
| Spindle speed | rpm | Spindle speed. |
| Unit power of the material | kW per cm³/min | Unit power for spade drilling the work material (from tooling or handbook data for the material and hardness). |
| Machine mechanical efficiency | Mechanical efficiency of the machine drive (about 0.9 belt direct drive, 0.75 back gear, 0.7–0.8 geared head). | |
| Allowance for tool wear | % | Increase for a dulling tool (the handbook suggests 25–50% for a dull tool). |
| Motor power available | kW | Rated motor power of the machine. |
Method and formulas
- Power at the cutter kW_c = ukw × (π D² ÷ 4) × f × N ÷ 1000.
- Thrust B_s = 22,500 × ukw × f × D newtons (US form 148,500 uhp f D pounds).
- Motor power = kW_c ÷ e_m; wear allowance applied to both power and thrust.
- Example: a 40 mm spade drill at 0.3 mm/rev and 300 rpm needs 6.3441 kW at the motor.
Limitations
- Values for sharp tools; dull tools raise power and thrust 25–50%.
- Unit power varies with hardness and tool geometry.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check whether a machine can drive a large spade drill
- Size fixturing against drilling thrust
- Compare feeds for power and thrust
Who it is for
- Machinists
- Toolmakers
- Manufacturing engineers
What you get
- Power at the cutter and motor
- Thrust force
- Machine utilisation
Interpreting the result
- Reduce feed before speed if thrust is the limit; reduce speed if power is.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1077–1079. Topic reference; no source tables or recommended settings are reproduced.
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