5.3.2 Machining

Machining, or chip-making operations are used to bring the forging to its final form and dimensional tolerance. Forgings are generally machined with essentially the same machinery and cutting tools as equivalent castings and weldments.

The amount of machining varies with the required dimensional precision and forging process. Forgings made by the open die process and those made from blocker dies generally require a significant amount of finish machining, whereas net shape forgings typically require few or no finish machining operations. The cost of machining may be affected by the following factors, which should be identified and discussed between the purchaser and forger:

1. Some alloy additions that enhance machinability and reduce machining costs may also reduce forgeability, and thereby increase processing costs.
2. The cost of machining must often be traded off against the potential additional processing and tooling costs associated with forging to closer tolerances. Purchased quantities will usually affect the tradeoffs.
3. The cost of machining may be minimized by optimizing the allocation of machining responsibility between the forger and the purchaser.