Closed Die vs Open Die Forging
Closed die forging uses shaped dies to produce repeatable near-net parts; open die forging shapes metal freely between simple tools. The choice is driven almost entirely by quantity and geometric complexity.
- Tooling Cost
- Closed die: high; Open die: none
- Tolerance
- Closed die tighter by 2–3 classes
- Machining Allowance
- Closed die 1–3 mm; Open die 4–15 mm
- Minimum Quantity
- Closed die 500; Open die 1
- Geometry
- Closed die complex; Open die simple
- Lead Time
- Closed die 3–5 wks; Open die 1–3 wks
Closed Die vs Open Die Forging at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Tooling Cost: Closed die: high; Open die: none
- Tolerance: Closed die tighter by 2–3 classes
- Machining Allowance: Closed die 1–3 mm; Open die 4–15 mm
- Minimum Quantity: Closed die 500; Open die 1
- Geometry: Closed die complex; Open die simple
- Lead Time: Closed die 3–5 wks; Open die 1–3 wks
Tooling: the Deciding Factor
A closed die is a significant investment that produces near-net parts fast and repeatably. Open die needs no dedicated tooling at all, so a single piece is viable — at the cost of tolerances, machining allowance and cycle time.
- Closed die: high tooling, low piece cost
- Open die: zero tooling, higher piece cost
- Closed die: repeatable near-net
- Open die: flexible, one-off capable
Geometry Limits
Closed die produces ribs, bosses, forks and complex three-dimensional forms. Open die produces shafts, discs, blocks, rings and simple stepped shapes — nothing that requires a cavity.
Practical Decision Rule
Below roughly 100 pieces, or for a single replacement, open die. Above 500 pieces with repeat demand, closed die. Between the two, the machining content of the part usually settles it.
Topics covered on this page
- closed die vs open die forging
- difference open and closed die forging
- which forging process to choose
- impression die vs free forging
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
Which process is cheaper?
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For one-offs and small batches, open die by a wide margin. For volume production, closed die is far cheaper per piece once the die is paid for.
Can open die forging make complex shapes?
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No. It produces shafts, discs, blocks and rings. Complex geometry needs a die cavity.
What machining allowance does open die need?
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Typically 4–15 mm depending on size, against 1–3 mm for closed die.
Can I start with open die and move to closed die?
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Yes, that is a common development path — prototype open die, then invest in tooling once the design is proven.