KEVOS® MAKEOS · Mechanics
Average Force of a Blow (Drop Hammer or Pile Driver)
What average force does this falling weight deliver when it drives the work a given distance?
Average force of a blow from a falling weight — a drop hammer, pile driver or drop-test mass — by equating the work of the fall (including the penetration) with force × penetration, with impact speed, energy and an efficiency for losses.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Falling mass | kg | Mass of the ram, hammer or drop weight. |
| Drop height before contact | m | Height of the drop to first contact. |
| Penetration or set per blow | mm | Distance the work moves (deforms or is driven) during the blow. |
| Efficiency (share of energy into the work) | % | Fraction of the energy that does useful work; the handbook formula neglects losses (100%). |
Method and formulas
- Work of fall = W S, with S the total height including the penetration d.
- Average force × d = W S, so F = η m g (h + d) ÷ d.
- Impact speed = √(2 g h).
- Example: 500 kg falling 1.5 m with a 10 mm set delivers about 740.4 kN.
Limitations
- Average force only; peak force is higher and depends on stiffness.
- Losses from rebound, heat and elastic strain reduce the useful force.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Estimate the force delivered by a drop hammer or press
- Size a stop or anvil for a drop test
- Check pile driving resistance from set per blow
Who it is for
- Forging supervisors
- Test engineers
- Civil and site engineers
What you get
- Average force of the blow
- Impact speed and energy
- Force in weight terms
Interpreting the result
- Halving the penetration doubles the average force: hard stops see very high forces.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 183–184. Topic reference; no source tables or recommended settings are reproduced.
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