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