KEVOS® MAKEOS · Manufacturing
Spade Drilling Plan (Speed, Power, Thrust, Time)
At my cutting speed and feed, what power and thrust does this spade drill need, will the machine take it, and how long is each hole?
Plan for drilling a large hole with a spade drill: spindle speed from the cutting speed held to the machine maximum, metal removal rate, cutting and motor power with a tool wear allowance and thrust (as the spade drilling power tool), drilling time for the depth plus approach, checked against the motor power and the machine’s thrust limit.
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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. |
| Cutting speed | m/min | Cutting speed at the drill periphery (your value for the material). |
| Feed per revolution | mm/rev | Feed per spindle revolution. |
| Hole depth | mm | Depth of the hole. |
| Approach and breakthrough | mm | Extra travel for approach and breakthrough. |
| Unit power of the material | kW per cm³/min | Unit power of the work material. |
| Machine mechanical efficiency | Mechanical efficiency of the spindle drive. | |
| Allowance for tool wear | % | Extra power and thrust for a worn drill. |
| Machine | ||
| Largest spindle speed | rpm | Highest spindle speed of the machine. |
| Motor power available | kW | Spindle motor power. |
| Largest feed thrust | N | Largest thrust the feed drive and spindle bearings take. |
Method and formulas
- n = min(1000 v_c ÷ π D, n_max).
- MRR = π D² ÷ 4 × f × n; cutting power = unit power × MRR × wear allowance; motor power = cutting ÷ efficiency; thrust from the handbook relation for spade drills (as the spade drilling power tool).
- Time = (depth + approach) ÷ (f × n).
- Example: at 238.73 rpm the drill needs 5.0484 kW and 12,116 N thrust; each hole takes 54.454 s.
Limitations
- Through or blind holes with good chip removal; deep holes need pecking or coolant-fed drills.
- Unit power and wear allowance as entered.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a machine for large-diameter drilling
- Set feed so the thrust stays within the spindle limit
- Estimate drilling time
Who it is for
- Machinists
- Process planners
- CNC programmers
What you get
- Spindle speed and metal removal rate
- Motor power and thrust
- Drilling time
Interpreting the result
- If the thrust is too high, reduce the feed: thrust falls in proportion while the power falls too.
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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