- Practice · 6 marks
Forging hammers, presses, advantages and limits
Short answer
Forging hammers deliver a high‑velocity impact, deforming mainly surface layers; presses slowly squeezze, deforming the full depth. Advantages: grain flow gives high strength and toughness, eliminates voids, good surface in closed dies. Limitations: costly dies, difficult complex shapes, scale and poor dimension in hot forgig, not for brittle metals.
Differentiate between forging hammers and forging presses. State the advantages and limitations of forging.
Forging hammers and presses
| Forging hammer | Forging press |
|---|---|
| Energy is delivered as a high-velocity blow (impact) | Squeezing action with slow, steady pressure |
| Types: board, drop, steam/air, power hammer | Types: mechanical (crank, eccentric), hydraulic, screw |
| Deformation mostly on the surface layers | Deformation reaches the full depth of the job |
| Noise, vibration; needs heavy foundation | Quiet, smooth operation |
| Dies wear quickly; lower accuracy | Better dimensional accuracy; less draft needed |
| Capacity in kg of falling weight | Capacity in tonnes of force |
| Cheaper, used for small and medium work | Costly; suits large and heavy forgings |
Drop hammer: ram falls under gravity (board or steam-lifted) on the heated billet in a die. Power hammer: steam or compressed air drives the ram down faster.
Advantages of forging
- Grain flow follows the shape, giving high strength, toughness and fatigue resistance.
- Removes internal voids and blowholes; gives dense structure.
- Good for small and large parts, produces a good surface and accuracy in closed dies.
- Material saving over machining from solid.
Limitations
- High cost of dies and equipment for small batches.
- Complex shapes with deep cavities and undercuts are difficult.
- Hot forging gives scale and poor surface and dimensional accuracy.
- Not suitable for brittle metals; needs heating and skilled operation; some safety risk.
✓ Answer checked by Claude Opus 5.5 (high effort)
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