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Extended Metalforming Glossary

Automatic Press – A press with built-in electrical and pneumatic control in which the work is fed mechanically through the press in synchronism with the press action.
Automatic Press Stop – A machine-generated signal for stopping the action of a press, usually after a complete cycle, by disengaging the clutch mechanism and engaging the brake mechanism.

Bolster Plate – A plate to which dies can be fastened- the assembly is secured to the top surface of a press bed.
Blank – The piece of sheet metal, produced in cutting dies, that is to be subjected to further press operations. A blank may have a specific shape developed to facilitate forming or to eliminate a trimming operation subsequent to forming.
Blanking – The act of cutting a blank.
Blank Holder – The part of a forming die which holds the blank by pressure against a mating surface of the die to control metal flow and prevent wrinkling. The blank holder is sometimes referred to as “hold down” or binder area. Pressure is applied by mechanical means, springs, air, or fluid cushions.
Blank Holder Pressure – The pressure exerted by the blank holder against the blank. This is normally adjustable to control metal flow during drawing.

Cam – A device to move or do work at an angle to the press stroke.
Cam Action – A motion at an angle to the direction of an applied force achieved by a wedge or cam.
C-Frame Press – A press having uprights or housing resembling the letter “C”. Also called gap frame or overhanging press. See gap-frame press.
Crank Press – A mechanical press whose slides are actuated by a crankshaft.
Compound Die – Any die designed to perform more than one operation on a part with one stroke of the press, such as blanking and piercing, in which all functions are performed simultaneously within the confines of the blank size being worked.
Clamping Pressure – Pressure applied to a limited area of the sheet surface, usually at the periphery, to control or limit metal flow during forming.
Coining – A process of cold forming metals in which the metal is shaped between two dies in such a manner as to fill the depression of both dies in relief by displacement of the material.
Cupping – A press forming operation in which a cup shaped part is produced from sheet metal. Cupping is often the first operation in the production of a complex deep drawn part.
Cut-Off Die – Sometimes called a trimming die. The cut-off die can be the last die in a set of transfer dies which cuts the part loose from scrap. It can also be a die which cuts straight-sides blanks from a coil for later use in a draw die.

Daylight – The maximum clear distance between the pressing surfaces of a press when the surfaces are in the usable open position. Where a bolster plate is supplied, it is considered the pressing surface. See also shut height.
Deep Drawing – A drawing operation where a part is produced from a blank by the action of a punch in which the sheet is pulled into a die cavity and the flange of the blank is compressed in the circumferential direction. The area directly under the punch remains undeformed.
Developed Blank – A flat blank with a shape that will produce a finished part with the desired configuration and a minimum of trimming operations.
Die – A complete set of stations (tool) used in a press for any operation or series of operations, such as forming, impressing, piercing and cutting. The upper member(s) are attached to the slide(s) of the press and the lower member is clamped or bolted to the bed or bolster with the die members being so shaped as to cut or form the material placed between them when the press makes a stroke.
Die Clearance – The space on each side, between punch and die that metal fills during the process and is typically tight to the punch.
Die coating – Hard metal incorporated into the working surface of a die to protect the working surface or to separate the sheet metal surface from direct contact with the basic die material. Hard chromium plating is an example.
Die Cushion – A press accessory placed beneath or within a bolster plate or die block to provide an additional motion or pressure for stamping or forging operations; actuated by air, oil, rubber, springs, or a combination of these.
Die Height – The distance from the finished top face of the upper shoe to the finished bottom face of the lower shoe immediately after the die operation and with the work in the die.
Die Shoes – The 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 slide.
Double-action Mechanical Press – A press having two independent parallel movements by means of two slides, one moving within the other. The inner slide or plunger is usually operated by a crankshaft; the outer or blankholder slide, which dwells during the drawing operation, is usually operated by a toggle mechanism or by cams.

Eccentric Gear – A main press-drive gear with the eccentrics as an integral part. The unit rotates about a common shaft, with the eccentric transmitting the rotary motion of the gear into the vertical motion of the slide through a connection.
Eccentric Press – A mechanical press in which an eccentric, instead of a crank shaft, is used to move the slide.
Ejecting – The removal of a part from a die by an air blast or mechanical means.
Ejector – A mechanism for removing a part from a die. Also called kicker or knock-out.
Ejector Rod – A rod used to push out a formed piece.

Flanging – A bending operation in which a narrow strip at the edge of a sheet is bend down (up) along a straight or curved line. It is used for edge strengthening, appearance, rigidity and the removal of sheared edges. A flange is often used as a fastening surface.
Flying Shear – A machine for cutting continuous rolled products to length that does not require a halt in rolling, but rather moves along the runout table at the same speed as the product while performing the cutting, and then returns to the starting point in time to cut the next piece.
Free-shoe Die – A die constructed so the upper shoe is linked to the lower shoe and not secured in any way to the press ram, used for blanking or secondary cutting operations. Also called bumper-actuated die.

Gap-frame Press – A general classification of press in which the uprights or housings are made in the form of a letter C, thus making three sides of the die space accessible. See C-frame press.
Grid Analysis – A process used to measure the mechanical properties of a sheet metal part during a forming operation.
Guide Pin – Pin or post usually fixed in the lower shoe and accurately fitted to bushings in the upper shoe to insure precise alignment of the two members of a die set. Also called a guide post, rider pin, or leader pin.

Hem – A bend of 180’ made in two steps. First, a sharp-angle bend is made; next, the bend is closed using a flat punch and a die.
Hemming Die – A die which folds the edge of the part back over on itself. The edge may or may not be completely flattened to form a closed hem.
Hold-down Plate (Pressure Pad) – A pressurized plate designed to hold the workpiece down during a press operation. In practice, this plate often serves as a stripper and is also called a stripper plate.
Hydraulic Shear – A shear in which the crosshead is actuated by hydraulic cylinders.

Knockout Pin – A power-operated plunger installed in a die to aid removal of the finished forging.

Limit Switch – A type of electric switch used to control the operations of a machine automatically.

Notching – The cutting out of various shapes from the edge of a strip, blank, or part.

Progressive Die – A die with two or more stations arranged in line for performing two or more operations on a part, one operation usually being performed at each station. The parts are connected by a carrier strip until final parting or cutoff operation.

Roll Forming – A metal forming process used to produce long components of various cross sections. The sheet metal is formed by passing it through a succession of progressively shaped power-driven contoured rolls.
Rotary Shear – A sheet metal cutting machine with two rotating-disk cutters mounted on parallel shafts driven in unison.

Scrap Cutter – A shear or cutter operated by the press or built into a die for cutting scrap into sizes for convenient removal from the die or disposal.
Shut Height – The distance from the top of the bed to the bottom of the slide with the stroke down and adjusted up. In general, the shut height of a press is the maximum die height that can be accommodated for normal operation, taking the bolster into consideration.
Slide Adjustment – The distance that a press slide position can be altered to change the shut height of the die space. The adjustment can be made by hand or by power mechanism.
Slide Counterbalance – A device used on the slide of large and small presses to reduce vibration and to assist the brake and clutch in functioning properly. Counterbalances are actuated by springs or air pressure. They relieve much of the load of the slide and punch from the press connection and shaft, thereby reducing the friction on the brake.

Throat (Gap) – The open space in a gap-frame press behind the slide center line.
Transfer Die – (1) A die where the parts are blanked before or at the beginning of the operations and a mechanical transfer device which is part of the die moves the workpiece from station to station. This type is run in a conventional press. (2) A succession of small or sub dies all mounted in one transfer press to make a part with the parts being moved from one die to another with a mechanical transfer device which is part of the press.
Transfer press – A press having an integral mechanism for transfer and control of the workpiece.