What is the difference between opendie and impressiondie for

What is the difference between open-die and impression-die forging?

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Solution

Open Die Forging
The metal being shaped during open die forging is not completely confined during the process, which derives the name open die forging. Open die forging uses hammers and presses to shape metal parts anywhere from 5 to 500,000 lbs.

The open die forging process allows for some irregularities between forgings. The metal is usually rough machined and then finish machined to achieve final dimensions.

The metal used in open die forging may be heated to above recrystallization temperature and then reheated several times before the final product is achieved.

Impression Die Forging
In impression die forging, two dies are brought together, squeezing the metal causing it to fill the die impression. Depending on the design, metal can be allowed to flow outside of the dies or can be allotted no escape. The impression die forging process usually requires one hit through a die cavity for the metal.

The impression die forging process relies heavily on the work of the dies and less on the work of the operator.