Open Die Forgings
Open die forging shapes heated metal between flat or simple dies that do not enclose the workpiece, using repeated blows or presses to form shafts, rings, discs, blocks and custom shapes. It suits large parts and low volumes with no special tooling cost.
What it is
A skilled operator manipulates the hot billet between the dies, drawing it out, upsetting it or piercing it to reach the rough shape. Seamless rolled rings are also made by piercing and rolling.
Open-die forgings are supplied with machining allowance and usually rough or finish machined to size.
Typical applications
- Large shafts and spindles
- Discs, blanks and tube sheets
- Seamless rolled rings and flanges
- Blocks for dies and moulds
- Heavy engineering components
Suitable materials
- Carbon steels (EN8, C45, 1045)
- Alloy steels (EN19, EN24, 42CrMo4, 20MnCr5)
- Stainless steels (304, 316, 410, 17-4 PH)
- Aluminium, brass and copper alloys
- Tool steels and die blocks
Points to consider
- Economical for one-offs and low volumes because no special die is needed.
- Larger machining allowances than closed-die forgings.
- Specify ultrasonic testing for critical shafts and rings.
- State forging ratio or reduction requirements if specified by your standard.
Frequently asked questions
What is open die forging used for?
Large or simple shapes such as shafts, discs, rings and blocks, especially in low volumes.
Does open die forging need a die for each part?
No. Standard flat or shaped dies are used, so there is no part-specific tooling cost.
Are open die forgings accurate?
They are rough shapes with machining allowance; final accuracy comes from machining.