Glossary

ALL

Air-lift hammer

A type of gravity-drop hammerA machine that applies a sharp blow to the work area through the fall of a ram onto an anvil. The ram can be driven by gravity or power. See also Gravity Hammer and Power-Driven Hammer. in which the ramThe main reciprocating member of a press, guided in the press frame, to which the punch or upper die is fastened. is raised for each strokeThe vertical movement of a ram during half of the cycle, from the full open to the full closed position or vice versa. by an air cylinder. Because the length of stroke can be controlled, ram velocity and therefore the energy delivered to the workpiece can be varied. See also Drop HammerA term generally applied to forging hammers wherein energy for forging is provided by gravity, steam, or compressed air. See also Air-Lift Hammer, Board Hammer, Steam Hammer. and Gravity HammerA class of forging hammer wherein energy for forging is obtained by the mass and velocity of a freely falling ram and the attached upper die. Examples are board hammers and air-lift hammers..

Aircraft quality

Denotes stockThe material to be forged regardless of form. Also, an individual piece of metal used to produce a single forging. of sufficient quality to be forged into highly stressed parts for aircraft or other critical applications. Such materials are of extremely high quality, requiring closely controlled, restrictive practices in their manufacture in order that they may pass rigid requirements, such as magnetic particle inspection.

Alloy steel forging

One made from a steel containing additional alloying elements other than carbon (e.g., Ni, Cr, Mo) to enhance physical and mechanical properties and/or heat-treat response.

AMS

Aeronautical Materials Specification.

As forged

The condition of a forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. as it comes out of the finisherThe die impression that imparts the final shape to a forged part. cavityThe machined recess in a die that gives the forging its shape. without any subsequent operations.

ASTM (Specifications)

The American Society for TestingA nondestructive method of inspection/testing for determining the existence and extent of possible defects in ferro-magnetic materials. The metal is magnetized, then iron powder is applied. The powder adheres to lines of flux leakage, revealing surface and near-surface discontinuities.... More and Materials.

Auxiliary operations

Additional processing steps performed on forgings to obtain properties, such as surface conditions or shapes, not obtained in the regular processing operation.

Axial rolls

In ring rolling, vertically displaceable, tapered rolls, mounted in a horizontally displaceable frameThe main structure of a press. opposite from but on the same centerline as the main roll and rolling mandrelA blunt-ended tool or rod used to retain or enlarge the cavity in a hollow metal product during forging.. The axial rollsIn ring rolling, vertically displaceable, tapered rolls, mounted in a horizontally displaceable frame opposite from but on the same centerline as the main roll and rolling mandrel. The axial rolls control the ring height during the rolling process. control the ring height during the rolling process.

Axisymmetric forging

A forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. where metal flow, during deformation, is predominately in a direction away from a common axis in a radial direction.

Backward extrusion

Forcing metal to flow in a direction opposite to the motion of a punch or dieThe machined recess in a die that gives the forging its shape..

Bar

A section hot rolled from a billetA semifinished, cogged, hot-rolled, or continuous-cast metal product of uniform section, usually rectangular with radiused corners. Billets are relatively larger than bars. See Bloom. to a form, such as round, hexagonal, octagonal, square, or rectangular, with sharp or rounded corners or edges, with a cross-sectional area of less than 16 sq in. (A solid section that is long in relation to its cross-sectional dimensions, having a completely symmetrical cross section and whose width or greatest distance between parallel faces is 3/8 in. or more).

Bar end

See End LossBar end left over after cutting bar lengths of stock into forging multiples. See also Multiple..

Barreling

Convexity of the surfaces of cylindrical or conical bodies, often produced unintentionally during upsetting or as a natural consequence during compression testingA nondestructive method of inspection/testing for determining the existence and extent of possible defects in ferro-magnetic materials. The metal is magnetized, then iron powder is applied. The powder adheres to lines of flux leakage, revealing surface and near-surface discontinuities.... More. See also Compression Test.

Batch/batch-type furnace

A furnace for heating materials where all loading and unloading is done through a single door or slot.

Bend or twist (defect)

Distortion similar to warpageTerm generally applied to distortion that results during quenching from heat-treating temperatures; hand straightening, press straightening, or cold restriking is employed, depending on the configuration of the part and the amount of warpage involved. The condition is governed by applicable straightness tolerances; beyond tolerances, warpage is defect and cause for rejection. The term is not to be confused with "bend" or "twist."... More, but resulting from different causes; generally caused in the forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. or trimming operations. When the distortion is along the length of the part, it is called “bend”; when across the width, it is called “twist.”

Bender

A die impressionThe portion of the die surface that shapes the forging., tool, or mechanical device designed to bend forging stockA wrought rod, bar, or other section suitable for subsequent change in cross section by forging. to conform to the general configuration of dieThe machined recess in a die that gives the forging its shape. impressions subsequently to be used.

Bending

A preliminary forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. operation to give the piece approximately the correct shape for subsequent forming.

Billet

A semifinished, cogged, hot-rolled, or continuous-cast metal product of uniform section, usually rectangular with radiused corners. Billets are relatively larger than bars. See BloomA semifinished product of square, rectangular, or even round cross section, hot rolled, or forged. For steel, the width of a bloom is not more than twice the thickness, and the cross sectional area is usually not less than about 36 sq. in. No invariable rule prevails for distinguishing between blooms and billets; the terms are frequently used interchangeably.... More.

Bite

Amount of the dieThe machined recess in a die that gives the forging its shape. in contact with the workpiece throughout one entire forging reductionRatio of the cross-sectional areas before and after forging; sometimes refers to percentage reduction in thickness., e.g., heavy biteAmount of the die in contact with the workpiece throughout one entire forging reduction, e.g., heavy bite is three-quarter to full width of the die. is three-quarter to full width of the dieThe machined recess in a die that gives the forging its shape..

Blank

Raw material or forging stockA wrought rod, bar, or other section suitable for subsequent change in cross section by forging. (also called a “slug” or “multiple”) from which a forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. is made.

Blast cleaning

A process for cleaningThe process of removing scale, oxides, or lubricant—acquired during heating for forging or heat treating—from the surface of the forging. (See also Blasting, Pickling, Tumbling.) or finishing metal objects by use of an air jet or centrifugal wheel that propels abrasive particles (grit, sand, or shot) against the surfaces of the workpiece at high velocity.

Block

The forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. operation in which metal is progressively formed to general desired shape and contour by means of an impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. dieThe machined recess in a die that gives the forging its shape. (used when only one blockThe forging operation in which metal is progressively formed to general desired shape and contour by means of an impression die (used when only one block operation is scheduled). operation is scheduled).

Block and finish

The forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. operation in which the part to be forged is blocked and finished in one heatAmount of forging stock placed in a batch-type furnace at one time. through the use of a dieThe machined recess in a die that gives the forging its shape. having both a blockThe forging operation in which metal is progressively formed to general desired shape and contour by means of an impression die (used when only one block operation is scheduled). impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. and a finish impressionThe die impression that imparts the final shape to a forged part. in the same dieThe machined recess in a die that gives the forging its shape.. This also covers the case where two tools mounted in the same machine are used, as in the case of aircraft pistons. Only one heatAmount of forging stock placed in a batch-type furnace at one time. is involved for both operations.

Block, first and second

Blocking operation performed in a dieThe machined recess in a die that gives the forging its shape. having two blocking cavities in the same dieThe machined recess in a die that gives the forging its shape.; the part being forged is successively blocked in each impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. all in one heatAmount of forging stock placed in a batch-type furnace at one time.. As many as three blocker diesThe metal blocks into which forging impressions are machined and from which forgings are produced. are sometimes needed for some forgings and up to three operations are sometimes required in each die.

Block, first, second, and finish

The forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. operation in which the part to be forged is passed in progressive order through three tools mounted in one forging machineA type of forging equipment, related to the mechanical press, in which the main forming energy is applied horizontally to the workpiece, which is gripped and held by prior action of the grip dies.; only one heatAmount of forging stock placed in a batch-type furnace at one time. is involved for all three operations.

Blocker impression

The forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. die impressionThe portion of the die surface that shapes the forging. which gives the forging its general shape, but omits any details that might restrict the metal flow; corners are well rounded. The primary purpose of the blocker is to enable the forming of shapes too complex to be finished after the preliminary operations; it also reduces dieThe machined recess in a die that gives the forging its shape. wear in the finishing impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging..

Blocker-type forging

A forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. that approximates the general shape of the final part with relatively generous finish allowanceThe amount of stock left on the surface of the forging to be removed by subsequent machining. Also called "machining allowance" or "forging envelope." and radii. Such forgings are sometimes specified to reduce dieThe machined recess in a die that gives the forging its shape. costs where only a small number of forgings are desired and the cost of machining each part to its final shape is not exorbitant.

Bloom

A semifinished product of square, rectangular, or even round cross section, hot rolled, or forged. For steel, the width of a bloomA semifinished product of square, rectangular, or even round cross section, hot rolled, or forged. For steel, the width of a bloom is not more than twice the thickness, and the cross sectional area is usually not less than about 36 sq. in. No invariable rule prevails for distinguishing between blooms and billets; the terms are frequently used interchangeably.... More is not more than twice the thickness, and the cross sectional area is usually not less than about 36 sq. in. No invariable rule prevails for distinguishing between blooms and billets; the terms are frequently used interchangeably.

Board hammer

A type of gravity drop hammerA term generally applied to forging hammers wherein energy for forging is provided by gravity, steam, or compressed air. See also Air-Lift Hammer, Board Hammer, Steam Hammer. where wood boards attached to the ramThe main reciprocating member of a press, guided in the press frame, to which the punch or upper die is fastened. are raised vertically by action of contrarotating rolls, then released. Energy for forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. is obtained by the mass and velocity of the freely falling ram and the attached upper dieThe machined recess in a die that gives the forging its shape.. See also Drop HammerA machine that applies a sharp blow to the work area through the fall of a ram onto an anvil. The ram can be driven by gravity or power. See also Gravity Hammer and Power-Driven Hammer..

Bolster plate

A plate to which diesThe metal blocks into which forging impressions are machined and from which forgings are produced. can be fastened; the assembly is secured to the top surface of a pressA machine tool with a stationary bed and a slide or ram that has reciprocating motion at right angles to the bed surface; the ram is guided in the frame of the machine. bed. In press forgingThe shaping of metal between dies on a mechanical or hydraulic press. The action is that of kneading the metal by relatively slow application of force as compared with the action of hammering., such a plate may also be attached to the ramThe main reciprocating member of a press, guided in the press frame, to which the punch or upper die is fastened..

Boss

A relatively short protrusion or projection on the surface of a forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment., often cylindrical in shape.

Breakdown

(1) An initial rolling or drawing(1) A forging operation in which the cross section of forging stock is reduced and the stock lengthened between flat or simple contour dies. See also Fullering. (2) in heat treating, the same as tempering. operation, or a series of such operations, for reducing an ingotA casting intended for subsequent rolling, forging, or extrusion. or extruded shape to desired size before the finish(1) The forging operation in which the part is forged into its final shape in the finish die. If only one finish operation is scheduled to be performed in the finish die, this operation will be identified simply as finish; first, second, or third finish designations are so termed when one or more finish operations are to be performed in the same finish die. (2) The surface condition of a forging after machining. (3) The material machined off the surface of a forging to produce the finish machine component.... More reduction. (2) A preliminary press-forging operation.

Brinell hardness

The hardness of a metal or part, as represented by the number obtained from the ratio between the load applied on and the spherical area of the impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. made by a steel ball forced into the surface of the material tested. The Brinell HardnessThe hardness of a metal or part, as represented by the number obtained from the ratio between the load applied on and the spherical area of the impression made by a steel ball forced into the surface of the material tested. The Brinell Hardness Number (BHN) is determined by measuring the diameter of the impression using a low power microscope, then matching this diameter with the load on a standard table.... More Number (BHN) is determined by measuring the diameter of the impression using a low power microscope, then matching this diameter with the load on a standard table.

Buckling

A bulge, bend, kink, or other wavy condition of the workpiece caused by compressive stresses. See also Compressive Stress.

Burning

Permanently damaging a metal or alloy by heating so as to cause either incipient melting or intergranular oxidation.

Burr

A thin ridge or roughness left on forgings by cutting operation such as slitting, shearing, trimming, blanking, or sawing.

Buster (preblocking impression)

A type of die impressionThe portion of the die surface that shapes the forging. sometimes used to combine preliminary forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. operations such as edgingThe forging operation of working a bar between contoured dies while turning it 90° between blows to produce a varying rectangular cross section. and fulleringReducing the cross section of a forging between ends of stock. with the blocking operation to eliminate blows.

Buster (rougher)

An impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. employed in a dieThe machined recess in a die that gives the forging its shape. when considerable metal movement is required and which precedes a blocker cavityThe machined recess in a die that gives the forging its shape. and a finisherThe die impression that imparts the final shape to a forged part. cavityThe machined recess in a die that gives the forging its shape.. Also known as breakdown(1) An initial rolling or drawing operation, or a series of such operations, for reducing an ingot or extruded shape to desired size before the finish reduction. (2) A preliminary press-forging operation./pancake, scalebreak, cheese.

Carbon steel

Steel containing carbon up to about 1.2%, and only residual amounts of other elements except for those added for composition control, with silicon usually limited to 0.60 % and manganese to 1.65%.

Cassette

Also known as sub-bolster, dieThe machined recess in a die that gives the forging its shape. assembly, trimThe removal of the excess metal or flash produced during the forging process. The operation takes place in tools produced to the peripheral shape of the component, the component being pushed through the female impression by the identically-shaped male punch. The operation may be carried out hot or at room temperature.... More and pierceIn ring rolling, the process of providing a through hole in the center of an upset forging using a tapered or cylindrical punch. See Drifting. assembly. An assembly of top and bottom diesThe metal blocks into which forging impressions are machined and from which forgings are produced. and/or tools of each forming stationA regular stopping place in the die during the forging sequence. assembled into one unit.

Cast (proof)

Any reproduction of a dieThe machined recess in a die that gives the forging its shape. cavityThe machined recess in a die that gives the forging its shape. in any material, frequently lead, plaster or epoxy, used to confirm the exactness of the cavityThe machined recess in a die that gives the forging its shape.. See Die ProofA casting of the die impression made to confirm the exactness of the impression..

Cavity, die

The machined recess in a dieThe machined recess in a die that gives the forging its shape. that gives the forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. its shape.

Chamfer

To break or remove sharp edges or corners of forging stockA wrought rod, bar, or other section suitable for subsequent change in cross section by forging. by means of straight angle tool or grinding wheel.

Charpy impact test

An impact testTest to determine the energy absorbed in fracturing a notched test bar at high velocity. See also Charpy Test, Izod Test. in which a specially 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.

Check

Crack in a die impressionThe portion of the die surface that shapes the forging., generally due to forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. pressure and/or excessive dieThe machined recess in a die that gives the forging its shape. temperatureThe temperature of the forging stock just prior to forging.. Die blocksThe metal blocks into which forging impressions are machined and from which forgings are produced. too hard for the depth of the dieThe machined recess in a die that gives the forging its shape. impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. have a tendency to checkCrack in a die impression, generally due to forging pressure and/or excessive die temperature. Die blocks too hard for the depth of the die impression have a tendency to check or develop cracks in impression corners. or develop cracks in impression corners.

Chop

A dieThe machined recess in a die that gives the forging its shape. forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. defect; metal sheared from a vertical surface and spread by the dieThe machined recess in a die that gives the forging its shape. over an adjoining horizontal surface.

Chucking lug

A lug or bossA relatively short protrusion or projection on the surface of a forging, often cylindrical in shape. to the forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. so that “on center” machining and forming can be performed with one setting or chucking; this lug is machined or cut away on the finished item.

Cleaning

The process of removing scale, oxides, or lubricant—acquired during heating for forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. or heatAmount of forging stock placed in a batch-type furnace at one time. treating—from the surface of the forging. (See also Blasting, PicklingThe process of removing oxide scale from forgings by treating in a heated acid bath., Tumbling(1) The process for removing scale from forgings in a rotating container by means of impact with each other and abrasive particles and small bits of metal. (2) A process for removing scale and roughness from forgings by impact with each other, together with abrasive material in a rotating container.... More.)

Close-tolerance forging

One held to closer-than-conventional dimensional tolerances so that little or no machining is required after forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment.. See also Precision Forging(See also Net-shape forging) A forging produced to closer tolerances than normally considered standard by the industry..

Closed die forging

The shaping of hot metal completely within the walls or cavities of two diesThe metal blocks into which forging impressions are machined and from which forgings are produced. that come together to enclose the workpiece on all sides. The impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. for the forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. can be entirely in either dieThe machined recess in a die that gives the forging its shape. or divided between the top and bottom diesThe metal blocks into which forging impressions are machined and from which forgings are produced.. Impression-die forging, often used interchangeably with the term closed-die forging, refers to a closed-die operation in which the dies contain a provision for controlling the flow of excess material, or flashMetal in excess of that required to fill completely the blocking or finishing forging impression of a set of dies. Flash extends out from the body of the forging as a thin plate at the line where the dies meet and is subsequently removed by trimming. Because it cools faster than the body of the component during forging, flash can serve to restrict metal flow at the line where dies meet, thus ensuring complete filling of the impression. See also Closed-Die Forging.... More, that is generated. By contrast, in flashless forging"True" closed die forging in which metal deformed in a die cavity permits virtually no excess metal to escape., the material is deformed in a cavityThe machined recess in a die that gives the forging its shape. that allows little or no escape of excess material. See Impression Die ForgingA forging that is formed to the required shape and size by machined impressions in specially prepared dies that exert three-dimensional control on the workpiece..

Closing-in

The forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. operation that locally reduces diameters in hollow forgings.

Closure, die

A term frequently used to mean variations in thickness of a forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment..

Cogging

The reducing operation in which an ingotA casting intended for subsequent rolling, forging, or extrusion. is worked into a billetA semifinished, cogged, hot-rolled, or continuous-cast metal product of uniform section, usually rectangular with radiused corners. Billets are relatively larger than bars. See Bloom. by the use of a forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. hammerA machine that applies a sharp blow to the work area through the fall of a ram onto an anvil. The ram can be driven by gravity or power. See also Gravity Hammer and Power-Driven Hammer. or a forging pressA machine tool with a stationary bed and a slide or ram that has reciprocating motion at right angles to the bed surface; the ram is guided in the frame of the machine..

Coining

(1) A post-forging process—on hot or coldFaults produced in a forging by incorrect tool design or incorrect flow of steel that results in the formation of a crack in the forging surface. parts—used to attain closer tolerances or improved surfaces. (2) A closed-die squeezing operation in which all surfaces of a workpiece are confined or restrained, resulting in a well-defined imprint of the dieThe machined recess in a die that gives the forging its shape. on the work.

Coining dies

DiesThe metal blocks into which forging impressions are machined and from which forgings are produced. in which the coining(1) A post-forging process—on hot or cold parts—used to attain closer tolerances or improved surfaces. (2) A closed-die squeezing operation in which all surfaces of a workpiece are confined or restrained, resulting in a well-defined imprint of the die on the work.... More or sizingSecondary forming or squeezing operations needed to square up, set down, flatten, or otherwise correct surfaces to produce specified dimensions and tolerances. Often accomplished with a coining press. See Coining. operation is performed.

Cold forging

Various forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. processes conducted at or near ambient temperatures to produce metal components to close tolerances and net shape. These include bendingA preliminary forging operation to give the piece approximately the correct shape for subsequent forming., coldFaults produced in a forging by incorrect tool design or incorrect flow of steel that results in the formation of a crack in the forging surface. drawing(1) A forging operation in which the cross section of forging stock is reduced and the stock lengthened between flat or simple contour dies. See also Fullering. (2) in heat treating, the same as tempering., cold headingPlastically 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. See also Heading and Upsetting., coining(1) A post-forging process—on hot or cold parts—used to attain closer tolerances or improved surfaces. (2) A closed-die squeezing operation in which all surfaces of a workpiece are confined or restrained, resulting in a well-defined imprint of the die on the work.... More, extrusionThe process of forcing metal to flow through a die orifice in the same direction in which energy is being applied (forward extrusion); or in the reverse direction (backward extrusion), in which case the metal usually follows the contour of the punch or moving forming tool. The extrusion principle is used in many impression die forging applications.... More (forward or backward), punching, thread rolling and others.

Cold heading

Plastically deforming metal at ambient temperatures to increase the cross-sectional area of the stockThe material to be forged regardless of form. Also, an individual piece of metal used to produce a single forging. (either solid barA section hot rolled from a billet to a form, such as round, hexagonal, octagonal, square, or rectangular, with sharp or rounded corners or edges, with a cross-sectional area of less than 16 sq in. (A solid section that is long in relation to its cross-sectional dimensions, having a completely symmetrical cross section and whose width or greatest distance between parallel faces is 3/8 in. or more).... More or tubing) at one or more points along the longitudinal axis. See also HeadingThe upsetting of wire, rod, or bar stock in dies to form parts that usually contain portions that are greater in cross-sectional area than the original wire, rod, or bar. and Upsetting.

Cold lap

A flaw that results when a workpiece fails to fill the dieThe machined recess in a die that gives the forging its shape. cavityThe machined recess in a die that gives the forging its shape. during the first forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment.. A seam is formed as subsequent diesThe metal blocks into which forging impressions are machined and from which forgings are produced. force metal over this gap to leave a seam on the workpiece surface. See also Cold ShutAlso known as lap or fold. A defect such as lap that forms whenever metal folds over itself during forging. This can occur where vertical and horizontal surfaces intersect..

Cold saw

Mechanical sawing machine used to produce cut pieces prior to the forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. operation. Sawing is carried out on the material at ambient temperatureThe temperature of the forging stock just prior to forging..

Cold shut

Also known as lapA surface irregularity appearing as a fissure or opening, caused by the folding over of hot metal, fins or sharp corners and by subsequent rolling or forging (but not welding) of these into the surface. or foldA forging defect caused by folding the metal back on its own surface during its flow in the die cavity. See Lap.. A defect such as lap that forms whenever metal folds over itself during forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment.. This can occur where vertical and horizontal surfaces intersect.

Cold trimming

Removing flashMetal in excess of that required to fill completely the blocking or finishing forging impression of a set of dies. Flash extends out from the body of the forging as a thin plate at the line where the dies meet and is subsequently removed by trimming. Because it cools faster than the body of the component during forging, flash can serve to restrict metal flow at the line where dies meet, thus ensuring complete filling of the impression. See also Closed-Die Forging.... More or excess metal from the forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. in a trimming pressA power press suitable for trimming flash from forgings. when the forging is at room temperatureThe temperature of the forging stock just prior to forging..

Cold working

Permanent plastic deformation of a metal at a temperatureThe temperature of the forging stock just prior to forging. below its recrystallization point—low enough to produce strain hardeningAn increase in hardness and strength caused by plastic deformation at temperatures below the recrystallization range. Also known as work hardening.. Usually, but not necessarily, conducted at room temperatureThe temperature of the forging stock just prior to forging.. Also referred to as coldFaults produced in a forging by incorrect tool design or incorrect flow of steel that results in the formation of a crack in the forging surface. forming or cold forgingVarious 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.... More. Contrast with hot workingThe plastic deformation of metal at such a temperature and strain rate that recrystallization takes place simultaneously with the deformation, thus avoiding any strain hardening. Also referred to as hot forging and hot forming. Contrast with cold working.... More.

Cold-coined forging

A forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. that has been restruck coldFaults produced in a forging by incorrect tool design or incorrect flow of steel that results in the formation of a crack in the forging surface. in order to hold closer face distance tolerances, sharpen corners or outlines, reduce section thickness, flatten some particular surface, or, in non-heat-treatable alloys, increase hardness.

Concavity

A concave condition applicable to the width of any flat surface.

Controlled cooling

Cooling from an elevated temperatureThe temperature of the forging stock just prior to forging. in a predetermined manner to avoid hardening, cracking, or excessive internal stresses, or to produce a desired microstructureThe structure and internal condition of metals as revealed on a ground and polished (and sometimes etched) surface when observed at high magnification (over 10 diameters)..

Conventional forging

A forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. characterized by design complexity and tolerances that fall within the broad range of general forging practice.

Counterblow forging

One made by equipment incorporating two opposed rams, which simultaneously strike repeated blows on the workpiece.

Counterblow forging equipment

A category of forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. equipment in which two opposed rams are activated simultaneously, striking repeated blows on the workpiece at a midway point. Action is vertical or horizontal.

Cross forging

Preliminary working of forging stockA wrought rod, bar, or other section suitable for subsequent change in cross section by forging. in alternate planes, usually on flat diesThe metal blocks into which forging impressions are machined and from which forgings are produced., to develop mechanical properties, particularly in the center portions of heavy sections.

Decarburization

The removal of carbon from the surface of steel as a result of heating in a medium that reacts with the carbon. DecarburizationThe removal of carbon from the surface of steel as a result of heating in a medium that reacts with the carbon. Decarburization is usually present to a slight extent in steel forgings. Excessive decarburization can result in defective products. is usually present to a slight extent in steel forgings. Excessive decarburization can result in defective products.

Die holder

Also known as bolster, insertA piece of steel that is tightly fixed in a die. The insert may be used to fill a cavity, to replace a portion of the die with a grade of steel that is better suited for service at that point, or to function as a small die with the impression fastened to a master die.... More holder, can. Used to locate, clamp and support diesThe metal blocks into which forging impressions are machined and from which forgings are produced., dieThe machined recess in a die that gives the forging its shape. assemblies or dieThe machined recess in a die that gives the forging its shape. inserts.

Die impression

The portion of the dieThe machined recess in a die that gives the forging its shape. surface that shapes the forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment..

Die lubricant

A material sprayed, swabbed, or otherwise applied during forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. to reduce friction and/or provide thermal insulation between the workpiece and the diesThe metal blocks into which forging impressions are machined and from which forgings are produced.. Lubricants also facilitate release of the part from the diesThe metal blocks into which forging impressions are machined and from which forgings are produced. and provide thermal insulation. See also LubricantA material applied to dies, molds, plungers, or workpieces that promotes the flow of metal, reduces friction and wear, and aids in the release of the finished part..

Die match

Also known as mismatchThe misalignment or error in register of a pair of forging dies; also applied to the condition of the resulting forging.. The alignment of the upper (moving) and lower (stationary) impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. in the dieThe machined recess in a die that gives the forging its shape..

Die proof (cast)

A casting of the die impressionThe portion of the die surface that shapes the forging. made to confirm the exactness of the impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging..

Die set

The assembly of the upper and lower die shoesThe upper and lower plates or castings that constitute a die set (punch and die holder). Also a plate or block upon which a die holder is mounted, functioning primarily as a base for the complete die assembly. This plate or block is bolted or clamped to the bolster plate or the face of the press ram.... More (punch and dieThe machined recess in a die that gives the forging its shape. holders), usually including the guideThe parts of a drop hammer or press that guide the up-and-down motion of the ram in a true vertical direction. pins, guide pin bushings, and heel blocks. This assembly takes many forms, shapes, and sizes and is frequently purchased as a commercially available unit. Also, two (or, for a mechanical upsetterA three-element forging press, with two gripper dies and a forming tool, for flanging or forming relatively deep recesses., three) machined diesThe metal blocks into which forging impressions are machined and from which forgings are produced. used together during the production of a dieThe machined recess in a die that gives the forging its shape. forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment..

Die shift

The condition that occurs after the diesThe metal blocks into which forging impressions are machined and from which forgings are produced. have been set up in a forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. unit in which a portion of the impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. of one dieThe machined recess in a die that gives the forging its shape. is not in perfect alignment with the corresponding portion of the other dieThe machined recess in a die that gives the forging its shape.. This results in a mismatchThe misalignment or error in register of a pair of forging dies; also applied to the condition of the resulting forging. in the forging, a condition that must be held within the specified toleranceThe permissible deviation from a specification for any design characteristic..

Die shoes

The upper and lower plates or castings that constitute a die setThe assembly of the upper and lower die shoes (punch and die holders), usually including the guide pins, guide pin bushings, and heel blocks. This assembly takes many forms, shapes, and sizes and is frequently purchased as a commercially available unit. Also, two (or, for a mechanical upsetter, three) machined dies used together during the production of a die forging.... More (punch and die holderA block used as an adapter in order to permit the use of forging dies that otherwise would not have sufficient height to be used in the particular unit or to permit the use of dies in a unit where the shank sizes are different.). Also a plate or blockThe forging operation in which metal is progressively formed to general desired shape and contour by means of an impression die (used when only one block operation is scheduled). upon which a die holderA block used as an adapter in order to permit the use of forging dies that otherwise would not have sufficient height to be used in the particular unit or to permit the use of dies in a unit where the shank sizes are different. is mounted, functioning primarily as a base for the complete dieThe machined recess in a die that gives the forging its shape. assembly. This plate or block is bolted or clamped to the bolster plateA plate to which dies can be fastened; the assembly is secured to the top surface of a press bed. In press forging, such a plate may also be attached to the ram. or the face of the pressA machine tool with a stationary bed and a slide or ram that has reciprocating motion at right angles to the bed surface; the ram is guided in the frame of the machine. ramThe main reciprocating member of a press, guided in the press frame, to which the punch or upper die is fastened..

Die sinking

The process of machining impressions in die blocksThe metal blocks into which forging impressions are machined and from which forgings are produced..

Die straighten

A straightening operation performed in either a hammerA machine that applies a sharp blow to the work area through the fall of a ram onto an anvil. The ram can be driven by gravity or power. See also Gravity Hammer and Power-Driven Hammer. or a pressA machine tool with a stationary bed and a slide or ram that has reciprocating motion at right angles to the bed surface; the ram is guided in the frame of the machine. using flat or cavityThe machined recess in a die that gives the forging its shape. diesThe metal blocks into which forging impressions are machined and from which forgings are produced. to remove undesired deformation and bring the forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. within the straightness toleranceThe permissible deviation from a specification for any design characteristic..

Dies (die blocks)

The metal blocks into which forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. impressions are machined and from which forgings are produced.

Dies, forging

Forms for the making of forgings; generally consist of a top and bottom dieThe machined recess in a die that gives the forging its shape.. The simplest will form a completed forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. in a single impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging.; the most complex, made up of several dieThe machined recess in a die that gives the forging its shape. inserts, may have a number of impressions for the progressive working of complicated shapes. Forging diesForms for making forgings; they generally consist of a top and bottom die. The simplest will form a completed forging in a single impression; the most complex, consisting of several die inserts, may have a number of impressions for the progressive working of complicated shapes. Forging dies are usually in pairs, with part of the impression in one of the blocks and the rest of the impression in the other block.... More are usually in pairs, with part of the impression in one of the blocks and the balance of the impression in the other blockThe forging operation in which metal is progressively formed to general desired shape and contour by means of an impression die (used when only one block operation is scheduled)..

Dies, gripper

Clamping or lateral diesThe metal blocks into which forging impressions are machined and from which forgings are produced. used in a forging machineA type of forging equipment, related to the mechanical press, in which the main forming energy is applied horizontally to the workpiece, which is gripped and held by prior action of the grip dies. or mechanical upsetterA three-element forging press, with two gripper dies and a forming tool, for flanging or forming relatively deep recesses..

Direct (forward) extrusion

See ExtrusionThe process of forcing metal to flow through a die orifice in the same direction in which energy is being applied (forward extrusion); or in the reverse direction (backward extrusion), in which case the metal usually follows the contour of the punch or moving forming tool. The extrusion principle is used in many impression die forging applications.... More.

Directional properties

Properties whose magnitude varies depending on the relation of the test axis to a specific direction within the metal or alloy.

Disc (disk)

“Pancake” shaped forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. (flat with a round cross-section); e.g., a blankRaw material or forging stock (also called a "slug" or "multiple") from which a forging is made. for gears, rings and flanged hubs. Abbreviation is “D.”

Discontinuities

Includes cracks, laps, folds, coldFaults produced in a forging by incorrect tool design or incorrect flow of steel that results in the formation of a crack in the forging surface. shutsFaults produced in a forging by incorrect tool design or incorrect flow of steel that results in the formation of a crack in the forging surface., and flow-throughA forging defect caused by metal flow past the base of a rib with consequent rupture of the grain structure., as well as internal defects such as inclusion, segregation, and porosity; internal discontinuitiesIncludes cracks, laps, folds, cold shuts, and flow-through, as well as internal defects such as inclusion, segregation, and porosity; internal discontinuities can be detected and evaluated using ultrasonic testing equipment. can be detected and evaluated using ultrasonic testingA method of nondestructive testing of solid metal for internal flaws utilizing high-frequency sound waves. equipment.

Double forging

A forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. designed to be cut apart and used as two separate pieces.

Draft

The necessary taper on the side of a forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. to allow removal from the diesThe metal blocks into which forging impressions are machined and from which forgings are produced.; also applies to the die impressionThe portion of the die surface that shapes the forging.. Commonly expressed in degrees as the draft angleThe 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.. As applied to open die forgingForging worked between flat or simple contour dies by repeated strokes and manipulation of the workpiece. Also known as "hand" or "smith" forging. See Open-Die Forging., draftThe 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. 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.... More is the amount of relative movement of the diesThe metal blocks into which forging impressions are machined and from which forgings are produced. 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 forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. and the side walls of the die impressionThe portion of the die surface that shapes the forging..

Draftless forging

A forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. with zero draftThe 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. 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.... More on vertical walls.

Drawing

(1) A forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. operation in which the cross section of forging stockA wrought rod, bar, or other section suitable for subsequent change in cross section by forging. is reduced and the stockThe material to be forged regardless of form. Also, an individual piece of metal used to produce a single forging. lengthened between flat or simple contour diesThe metal blocks into which forging impressions are machined and from which forgings are produced.. See also FulleringReducing the cross section of a forging between ends of stock.. (2) in heatAmount of forging stock placed in a batch-type furnace at one time. treating, the same as tempering.

Drawing out

The forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. operation in which the length of a metal mass (stockThe material to be forged regardless of form. Also, an individual piece of metal used to produce a single forging.) is increased at the expense of its cross section; no “upset” is involved. The operation covers converting ingotA casting intended for subsequent rolling, forging, or extrusion. to pressed barA section hot rolled from a billet to a form, such as round, hexagonal, octagonal, square, or rectangular, with sharp or rounded corners or edges, with a cross-sectional area of less than 16 sq in. (A solid section that is long in relation to its cross-sectional dimensions, having a completely symmetrical cross section and whose width or greatest distance between parallel faces is 3/8 in. or more).... More using “V,” round, or flat diesThe metal blocks into which forging impressions are machined and from which forgings are produced..

Dressout

A condition where the dimensions of a part or forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. are changed by local grinding or machining to remove one or more defects thereby causing a localized imperfection of a maximum depth. The depth is the dimension of the dressoutA condition where the dimensions of a part or forging are changed by local grinding or machining to remove one or more defects thereby causing a localized imperfection of a maximum depth. The depth is the dimension of the dressout..

Drifting

In forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment., the operation of forming or enlarging a hole by use of a tapered punch.

Drop forging

A forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. made in closed or impressionA cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging. diesThe metal blocks into which forging impressions are machined and from which forgings are produced. under a drop or steam hammerA type of drop hammer where the ram is raised for each stroke by a double-action steam cylinder and the energy delivered to the workpiece is supplied by the velocity and weight of the ram and attached upper die driven downward by steam pressure. Energy delivered during each stroke may be varied.... More.

Drop hammer

A term generally applied to forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. hammers wherein energy for forging is provided by gravity, steam, or compressed air. See also Air-Lift HammerA type of gravity-drop hammer in which the ram is raised for each stroke by an air cylinder. Because the length of stroke can be controlled, ram velocity and therefore the energy delivered to the workpiece can be varied. See also Drop Hammer and Gravity Hammer.... More, Board HammerA type of gravity drop hammer where wood boards attached to the ram are raised vertically by action of contrarotating rolls, then released. Energy for forging is obtained by the mass and velocity of the freely falling ram and the attached upper die. See also Drop Hammer.... More, Steam HammerA type of drop hammer where the ram is raised for each stroke by a double-action steam cylinder and the energy delivered to the workpiece is supplied by the velocity and weight of the ram and attached upper die driven downward by steam pressure. Energy delivered during each stroke may be varied.... More.

Ductility

The property of a metal that enables it to stretch before rupturing.

Dwell

Portion of a pressA machine tool with a stationary bed and a slide or ram that has reciprocating motion at right angles to the bed surface; the ram is guided in the frame of the machine. cycle during which the movement of a member is zero or at least insignificant. Usually refers to the interval between the completion of the forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. strokeThe vertical movement of a ram during half of the cycle, from the full open to the full closed position or vice versa. and the retraction of the ramThe main reciprocating member of a press, guided in the press frame, to which the punch or upper die is fastened..