Industry News

Forging - Glossary

Aircraft quality — A high quality forging involved in controlled manufacturing processes that must pass a series of required tests before approval.

Alloy steel forging — A forging made from steel containing alloying elements other than carbon (e.g., Ni, Cr, Mo). These additional elements are used to enhance physical and mechanical properties and/or heat-treat response.

AMS — Aeronautical Materials Specification

As forged — Refers to the state of a forging as it comes out of the forging die.

ASTM — The American Society for Testing and Materials.

Axisymmetric forging — A type of forging that causes metal flow to move in a direction away from a common axis in a radial direction.

Batch-type furnace — A single door heat treating furnace used to heat treat materials.

Billet — A term used interchangeably with bloom. A billet is a semi finished metal product usually of rectangular shape and uniform section. Billets can be cogged, hot-rolled, or continuous-cast.

Bloom — A term used interchangeably with billet. A bloom is a semi finished metal product usually of square or rectangular shape. Blooms can be hot rolled or forged.

Brinell hardness — A rating of hardness for a metal part. The Brinell Hardness Number (BHN) is determined using a standard table. Critical information includes the diameter of the impression left by a metal ball that is pushed into the surface metal and the load applied on the ball during the impression.

Carbon steel — Steel that derives its physical properties from the presence of carbon.

Chamfer — Using a straight angle or a grinding wheel to break or remove the sharp edges or corners resulting from forging.

Charpy impact test — An impact test in which a special V-notched specimen is broken by the impact of a falling pendulum. The energy absorbed in fracture is a measure of the impact strength or notch toughness of the sample.

Closed die forging — A forging process that shapes hot metal as two dies exert pressure from both sides as they come together. Closed die forgings are supplied from ounces to almost 100 pounds each. Most forgings supplied by Ferralloy are machined complete to our customer’s requirements. Machined forgings are offered to the marketplace through our inventory stocking program to assist our customers in better inventory management as well as providing more timely deliveries.

Coining — A process used after initial forging to improve the surface of the forging or to attain closer tolerances — or— a closed die process that stamps the surface of a metal part with an imprint of the die.

Cold forging — Various forging processes conducted at or near ambient temperatures to produce metal components to close tolerances and net shape. These include bending, cold drawing, cold heading, coining, extrusion (forward or backward), punching, thread rolling and others.

Cold heading — Plastically deforming metal at ambient temperatures to increase the cross-sectional area of the stock (either solid bar or tubing) at one or more points along the longitudinal axis.

Cold lap — An error that is caused by the metal not completely filling the die during the forging process. Subsequent forging allows metal to fill in around the gap, however a seam forms between the layers of metal.

Cold shut — An error that occurs as metal folds over itself during the forging process. A cold shut commonly occurs where the vertical and horizontal surfaces meet.

Cold working — Forging at a temperature below the metal’s recrystallization point.

Concentricity — Adherence of part features to a common axis.

Decarburization — Using heat to remove carbon from the surface of steel.

Dies(forging) — Tools or devices for creating a desired shape, form, or finish with a source material. Dies range from simple to complex, requiring anywhere from one to a number of impressions to form the desired shape. In forging, dies are usually paired up to exert pressure on both sides of a metal part.

Draft — The taper on the side of a forging to allow removal from the dies; also applies to the die impression. It is Commonly expressed in degrees as the draft angle. As applied to open die forging, draft is the amount of relative movement of the dies toward each other through the metal in one application of power.

Draft angle — The angle of taper, expressed in degrees (usually 5° to 7°), given to the sides of the forging and the side walls of the die impression.

Extrusion — Shaping metal by a process that forces it through the die. Extrusion can take place using either forward or backwards force depending on product specifications.

Flash — The metal that extends out from the forging because it is in excess of the metal required to fill the die. Flash is typically removed by trimming.

Heat — The commonly used name for the product of a single melting operation.

Heat-resistant steel — Alloy steel designed for application at elevated temperatures.

Heat treatment — Creating metal parts with desired properties/specifications by using a sequence of controlled heating and cooling operations.

Induction heating — Heating metals by means of an alternating magnetic field.

Ingot — A casting that will undergo subsequent rolling, forging, or extrusion.

Lap — An error that occurs as metal folds over itself and causes surface irregularities that appear as fissures or openings.

Mandrel — A blunt-ended tool or rod used to retain or enlarge the cavity in a hollow metal product during forging.

Nonferrous — Metals like aluminum, copper and magnesium that contain no appreciable quantity of iron.

Open die forging — Forging when the metal being shaped is not completely confined during the process. The open die forging process uses hammers and presses to shape metal parts, usually using repeated strokes and continuous manipulation.

Pickling — Using a heated acid bath to remove oxide scale from forgings.

Rolled ring forgings — Produced in diameters up to 196” from carbon, alloy and stainless steel grades. Rolled ring forgings can be supplied in as forged condition or we can provide rough machining as well as machined complete rolled rings. The highly engineered ring rolling process utilizing state of the art computer controlled equipment, NC lathes and the Ferralloy, Inc. distribution model offers the marketplace immediate, measurable economic benefits.

SAE— The Society of Automotive Engineers.

Shot blasting — Using either centrifugal force or air pressure to propel metal at a high velocity at forgings. This process is designed to blast clean the forgings.

Shrinkage — The contraction of metal during cooling after hot forging. Die impressions are made oversize according to precise shrinkage scales to allow the forgings to shrink to design dimensions and tolerances.

Swaging — (1) Reducing the diameter of or rounding out a section of a forging by a series of blows, tapering the forging lengthwise until the entire section attains the smaller dimension of the taper. (2) Tapering forging stock by forging, hammering, or squeezing.