Die Lock
Die lock is a design problem discovered at the die trial, when it is expensive. Catching it at drawing review is the entire point of forgeability assessment.
Die lock occurs when a forging's geometry traps it in the die cavity so it cannot be ejected — typically caused by an undercut, a reverse taper or insufficient draft on an internal feature.
- Definition
- Geometry preventing die release
- Causes
- Undercuts, reverse taper, no draft
- Found at
- Die trial, or drawing review
- Solutions
- Draft, parting line change, machining
Die Lock at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Definition: Geometry preventing die release
- Causes: Undercuts, reverse taper, no draft
- Found at: Die trial, or drawing review
- Solutions: Draft, parting line change, machining
What Causes It
Any feature that is wider below than above in the withdrawal direction — an undercut, a reverse-tapered wall, a re-entrant boss. As the die opens, that feature has nowhere to go.
Design Around It
Add draft, relocate the parting line so the feature sits in one die half, split the feature across the parting line, or accept it as a machined feature. Split dies and side-acting tooling can solve it but multiply die cost.
Topics covered on this page
- die lock forging
- undercut forging design
- what is die lock
- forging release problem
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
What is die lock?
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A condition where the forging's geometry traps it in the die cavity so it cannot be ejected, usually from an undercut or missing draft.
How do you avoid die lock?
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Add draft, move the parting line, split the feature across die halves, or produce the feature by machining instead.
When is die lock usually discovered?
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At die trial if the drawing was not reviewed — which is why forgeability review before tooling matters.