Glossary of Terms


Adjustable Bed
(a) Bed of a press mounted and guided in the press frame and provided with a suitable mechanism, usually operated by power, for varying the die space height.
(b) The bed or table of a straight front press, such as a horning or wiring press, which is bolted to the straight, vertical, finished front surface of the press and supported by,
operated usually by a hand mechanism.

Adjustment of Slide

The distance that a mechanical press slide can be moved from its shut height to lessen the die space height. The adjustment may be by hand or by power mechanism.

Bed of a Press
The stationary part of the press serving as a table to which is affixed the bolster and sometimes the lower die direct.

Bench Press
Any small press of a size to be mounted on a bench or table.

The shearing or cutting of outside contours or shapes, called blanks, out of sheet or strip stock. For larger production, blanking is often done in multiple dies, and is combined with
other operations such as piercing and forming in combination dies and progressive dies.

Bolster Plate
A plate or block, sometimes called a die block, secured to the top of the bed of a press onto which the die is fastened. In some cases the die is fastened directly to the bed.

(a) Bending brake or press brake- A form of open frame, single action press comparatively wide between the housings, with bed designed for holding long narrow forming edges or dies. It is used for bending and forming strips and plates.
(b) The friction mechanism used for stopping or controlling the motion of a press, feed or other mechanism.

Capacity of Press
The rated capacity of a press is the ton pressure which the slide will safely exert at the bottom of the stroke in doing work within the range of the press. In a mechanical press
the capacity is usually based upon the capacity in bending
of the main shaft (crank, toggle, or eccentric shaft).

A coupling used to connect or disconnect a driving machine-member, such as a shaft or wheel, to or from a driven machine-member, such as another wheel or shaft. The engaging or disengaging may be done by a hand operated controlling device operated manually or by power or may be done automatically.

Crank Press
Mechanical press, the slide of which is actuated by a crankshaft.

Deep Drawing
Forming of deep recessed parts from sheet material by means of a plastic flow of the material worked in presses and dies.

The amount of bending or the deviation from a straight line or a plane when a force or load is applied to a surface of a machine member or part.

(a) A complete tool used on a press for any operation or series of operations, such as forming, impressing, piercing and cutting. The upper member (or members) are attached to slide (or slides) of the press, and the lower member is clamped or bolted to the bed or bolster, the die members being so shaped as to cut or form material placed between them when the press makes a stroke.
(b) The female part of complete die assembly as described in (a).
(c) A tool for cutting external threads.

Die Cushion
An attachment or accessory to a press which gives an additional motion or pressure required in many compound press operations. The pressure medium may be rubber, springs, air or liquid (usually oil), air (pneumatic) cushions being the most common. A few common uses of die
cushions are blankholding, drawing, maintaining uniform pressure on a die part, knock-out, and stripping. Although usually mounted in order a press bed, they are sometimes mounted on the top of a press slide flange.

Die Height
The closed height of a die with work, having had the completed operation, in the die. Projections for locating or fastening which extend below the main finished bottom face of the lower die, or above the main finished top face of the upper die (punch) are not includeding the die height. Die Height is measured from the top of the bolster plate to the bottom of the slide.

Double Action
Press having two independent parallel movements by means Mechanical Press of two slides, one slide operated by crankshaft, whereas, the outer or blankholder slide which dwells during the drawing process, is usually operated by a toggle mechanism or cams.

Double Crank Press

A mechanical single action press in which the slide is operated by two cranks and connections. There are two general classifications of Double crank Presses:
(a) Straight side press in which the uprights or housing are straight, thus enclosing the slides of the die space.
(b) Overhanging or gap frame presses in which the uprights or housings (parts of frame) are arched back leaving the top of the bed and die space clear for easy access for feeding. This classification is general and covers both single piece frame machines and built up or tie rod frame machines.

Essentially a disk arranged to rotate about a center, not the center of dish but parallel to it. An eccentric should be considered to crank with a crankpin of such size that it contains or surrounds the shaft. The eccentric with its strap or connection is used in the eccentric press. and for driving auxiliary attachments, such as liftouts and various types of feeds.

A wheel used on an engine or machine and whose rotation energy or inertia is used to prevent excessive or sudden changes in speed. In modern machines the flywheel is usually belted, chained or geared to the driving motor. In many medium and large machines, a clutch is mounted on or within the flywheel.

Flywheel Press
A mechanical press which has the flywheel mounted directly on the main crank or eccentric shaft without gearing. Sometimes called a plan or non-geared press.

Forging Press
(a) Hydraulic or steam-hydraulic presses used for rough forging from large ingots or billets. These machines are used to replace steam hammers.
(b) Mechanical or hydraulic press of heavy design used for accurate hot-forming (forging) operations in dies.

Gap Press
A general classification of presses in which the uprights or housing are made in the form of a letter ‘C’, thereby making both ends of the die space accessible.

Geared Press
A press whose main crank or eccentric shaft is connected to the driving source by on or more sets of gears, e.g., single geared, double geared, and triple geared. A triple geared machine will have three sets of gears and pinions and four driving shafts including the main crankshaft. A press it twin geared when there are two main gears on the crankshaft meshing with two main pinions on the first intermediate shaft.

Guides or shoes which insure the proper sliding fit between two machine parts and which usually are adjustable for taking up excessive wear, e.g., press gibs which guide the press slide.

High Production Press
A specialized design of automatic mechanical presses with rigid frames and comparatively lightweight slides and parts designed for high speed. These machines necessarily have compare timely short stroke, are built in one-piece or built-up frames and are arranged with various types of feeds to suite requirements.

Hydraulic Press
A press whose slid or ram is actuated by hydraulic cylinder and piston whose pressure is obtained from a hydraulic pump. The press cylinder, the pump, and the fluid
(usually oil) under pressure, together with connecting valves and controls from a hydraulic system which theoretically acts in accordance with the hydraulic principle.

A machine control process used in adjusting and setting of dies and other tools in which the motion of the working members is precisely controlled in short increments usually by rapidly engaging and disengaging the clutch usually though electric or pneumatic push buttons.

Inclinable Press
Small and medium size crank presses which may by inclined (tilted backward) to facilitate ejecting of finished parts by gravity. These presses are usually of the open-back, gap type
frame with right to left crankshaft. They are built in a maximum size of about 200 ton. They may be, and very often are, used in the upright or vertical position, being readily adjustable, usually by a hand mechanism, to any desired inclination up to the usual maximum of 45 degrees . The inclinable press is the most widely used type of press, being particularly adapted for blanking, piercing, forming and shallow drawings operations on a multitude of small and medium size parts. This type of press very frequently is equipped with mechanical feeds for rapid automatic production.

Knuckle Joint Press
(Also called Embossing or Coining Press) – A heavy, powerful comparatively short stroke press in which the slide is directly actuated by a single toggle (or knuckle) joint, which is closed and opened by means of a connection and crank. The knuckle joint press is built in capacities from 30 ton to 3,000 ton. It is used for embossing, coining, sizing, heading, swaging, and extruding.

Mechanical Press
A press whose slid or ram is operated by a crank, eccentric cam, toggle links or other mechanical means, as contrasted to fluid or other means.

Open Back Inclinable Press
The open back inclinable gap press is the most common small press. It is a one-piece frame machine with the opening at the back between the two gap uprights usually slightly more than the left to right dimension of the slide flange. Commonly referred to as an OBI Press.

The general term for cutting (shearing or punching) openings, such as holes and slots in sheet material, plate or parts. This is practically the same operation as blanking; The difference being that the slug or piece produced by piercing is scrap, whereas the blank produced by blanking is the useful part.
In the two cases the burr is opposite.

A connecting rod to convey motion and pressure from a revolving crank of eccentric to a sliding or swinging member, as a slide of lever. A press connection.

Pneumatic Die Cushion
Pneumatic (air) attachment consisting essentially of cylinder piston, pressure plate and accessories generally used with a press for clamping, blankholding or ejecting.

A machine having a stationary bed or anvil and a slide (ram or hammer) which has reciprocating motion toward and away from the bed surface and at right angles to the bed surface, the slide being guided in the frame of the machine to give a definite path of motion.

Progressive Dies
A series of two or more dies arranged in line for performing two or more operations on a part, one operation (single or compound) being performed in each die, that is at each station. Work in the form of a strip is usually fed to progressive dies automatically by a roll feed, or blanks or part are fed by a transfer feed.

Punch Press
(a) Punch (or punching) press is the name given to an end wheel gap press of the fixed bed type. Used commonly for piercing (punching) operations. (b) The name is used loosely to designate any mechanical press.

The most common name for the main reciprocating member of a press, guided in the press frame and to which the punch or upper die is fastened. It is sometimes called the ram. The inner slide of a double action press is called the plunger; the outer slide of a double action press is called the blankholder slide, and the slide of a hydraulic press is often called the platen.

Shut Height
The shut height as applied to an upright press is the distance from the top of the bed to the bottom of the slide with stroke down and adjustment up. The shut height must always be defined either from the top of the bed or from the top of the bolster. In a corresponding or similar manner the shut height of a horizontal or inverted press, or of a press with adjustable bed, can be defined. In general the shut height is equal to the maximum die-height of die that can be accommodated, taking the bolster into consideration.

Single Action Press
Any press with a single slide and usually considered to be without any other motion or pressure device which would affect the press working on the part.

Single-Point Press
A mechanical press in which the slide is operated by one connection.

Straight Side Press
Any mechanical press with uprights or housing having plain, flat sides (usually vertical) which bound or enclosed the left and right sides of the die space. This classification of presses includes many types and designs, such as single crank, double crank, eccentric, level, four point and enclosed presses. A straight-side hydraulic press is called a Housing Press.

The reciprocating motion of a press slide, usually specified as the number of inches between the terminal points of the motion.

Throat (gap)
The open space in a gap frame press back of the slide centerline. The depth of throat (gap) is the distance from the slide centerline back to the frame metal of the upright section.

Two-Point Press
A mechanical press in which the slide is operated by two connections.

If you come across a term that you are unfamiliar with consult a Heim Group engineer. Our trained technical staff can answer all of your questions and supply technical data sheets on press components.