Forging Terms and Definitions: C-F

From Cold working to Flashless forging
Courtesy of Forging Industry Association

Cold working: imparting plastic deformation to a metal or alloy at a temperature below recrystallization to produce hardness and strength increases via strain hardening.

Controlled cooling of forgings: used to attain required properties and/or corresponding microstructural phase changes; applies to heat-treatable steels (e.g., quenching) and to microalloyed steels, which require no heat treatment, but only controlled cooling to attain final properties.

Conventional forging: one that, by design, requires a specified amount of finish (or machining) to reach the final dimensional requirements.

Counterblow forging: one made by equipment incorporating two opposed rams, which simultaneously strike repeated blows on the workpiece.

Cross forging: the practice of working stock in one or more directions to make resultant properties more isotropic (equal in three directions) - e.g., by upsetting and redrawing the material.

Directional properties: refers to the inherent directionality within a forging such that properties are optimally oriented to do the most good under in-service conditions. Typically, maximum strength is oriented along the axis that will experience the highest loads.

Disc: "pancake" shaped forging (flat with a round cross-section); e.g., a blank for gears, rings and flanged hubs.

Draft: the necessary taper on the side of a forging to allow removal from the dies; also applies to the die impression. Commonly expressed in degrees as the draft angle.

Draftless forging: a forging with zero draft on vertical walls.

Drawing: (1) reducing the cross-section of forging stock while simultaneously increasing the length; (2) in heat treating, the same as tempering.

Drop forging: one produced by hammering metal in a drop hammer between impression dies.

Extrusion: forcing metal through a die orifice in the same direction as the applied force (forward extrusion) or in the opposite direction (backward extrusion).

Finish: (1) the material remaining after forging that is machined away to produce the final part; (2) the surface condition of a forging after machining.

Finish all over (F.A.O.): designates that forgings be made sufficiently larger than dimensions shown to permit machining on all surfaces to given sizes.

Finish allowance: amount of stock left on the surface of a forging to be removed by subsequent machining.

Flash: excess metal that extends out from the body of the forging to ensure complete filling of the finishing impressions.

Flashless forging: "true" closed die forging in which metal deformed in a die cavity permits virtually no excess metal to escape.

For more information about common forging terminology, visit the Forging Industry Association (FIA) website.

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