Closed-die forging

In practice

Forgings typically need 3–7° of draft, and die cost is justified at volumes from the low thousands up.

Where it comes up

• ForgingClosed-die and open-die forgings in carbon, alloy, and stainless steel and aluminum, with grain flow for strength.

Related terms

Open-die forging

Open-die forging is a forging process that shapes heated metal between flat or simple dies that do not fully enclose the workpiece, using repeated blows and repositioning. It suits large, simple shapes such as shafts, rings, and blocks at low volumes, with machining to finish.

Flash

Flash is excess material that escapes past the parting line or between die halves and hardens as a thin fin on the part. In molding and die casting it signals worn tooling, low clamp force, or excess pressure. In forging, flash is designed in on purpose, then trimmed off.

Trim die

A trim die is a press tool that shears flash, gates, runners, and overflows off a die casting or forging after it leaves the machine. Trim dies are a separate tooling line item, and complex parts can need more than one. Trimming leaves a slight witness line at the edge.