Engineering Definitions

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.

Source: The OHIO State University

Characterized by the production of a parallel-wall cup from a flat blank of sheet metal. The blank may be circular, rectangular, or a more complex shape. The blank is drawn into the die cavity by the action of a punch. Deformation is restricted to the flange areas of the blank. No deformation occurs under the bottom of the punch-the area of the blank that was originally within the die opening. As the punch forms the cup, the amount of material in the flange decreases. Also called cup drawing or radial drawing.

Source: The OHIO State University

The amount of deviation from a straight line or plane when a force is applied to a press member. Generally used to specify the allowable bending of the bed, slide, or frame at rated capacity with a load of predetermined distribution.

Source: The OHIO State University

In drawing, the limit of deformation is reached when the load required to deform the flange becomes greater than the load-carrying capacity of the cup wall. The deformation limit (limiting drawing ratio, LDR) is defined as the ratio of the maximum blank diameter that can be drawn into a cup without failure, to the diameter of the punch.

Source: The OHIO State University

A fluid forming process in which cylindrical and conical sheet metal parts are formed by a modified rubber bulging punch. The punch, equipped with a hydraulic cell, is placed inside the workpiece, which in turn is placed inside the die. Hydraulic pressure expands the punch.

Source: The OHIO State University

A sheet metal blank that yields a finished part without trimming or with the least amount of trimming.

Source: The OHIO State University

A tool, usually containing a cavity, that imparts shape to solid, molten, or powdered metal primarily because of the shape of the tool itself. Used in many press operations (including blanking, drawing, forging, and forming), in die casting, and in forming green powder metallurgy compacts. Die-casting and powder metallurgy dies are sometimes referred to as molds.

Source: The OHIO State University

The parts of a die stamp or press that hold the die and locate it for the punches.

Source: The OHIO State University

A block, often made of heat treated steel, into which desired impressions are machined or sunk and from which closed-die forgings or sheet metal stampings are produced using hammers or presses. In forging, die blocks are usually used in pairs, with part of the impression in one of the blocks and the rest of the impression in the other. In sheet metal forming, the female die is used in conjunction with a male punch.

Source: The OHIO State University

The machined recess that gives a forging or stamping its shape.

Source: The OHIO State University

Clearance between a mated punch and die; commonly expressed as clearance per side. Also called clearance or punch-to-die clearance.

Source: The OHIO State University

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

Source: The OHIO State University

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.

Source: The OHIO State University

A plate or block, on which the die block is mounted, having holes or slots for fastening to the bolster plate or the bed of the press.

Source: The OHIO State University

The portion of the die surface that shapes a forging or sheet metal part.

Source: The OHIO State University

The productive life of a die impression, usually expressed as the number of units produced before the impression has worn beyond permitted tolerances.

Source: The OHIO State University

A line or scratch resulting from the use of a roughened tool or the drag of a foreign particle between tool and product.

Source: The OHIO State University

In forging or forming, a compound that is sprayed, swabbed, or otherwise applied on die surfaces or the workpiece during the forging or forming process to reduce friction. Lubricants also facilitate release of the part from the dies and provide thermal insulation.

Source: The OHIO State University

The alignment of the upper (moving) and lower (stationary) dies in a hammer or press. An allowance for misalignment (or mismatch) is included in forging tolerances.

Source: The OHIO State University

A movable plate or pad in a female die; usually used for part ejection by mechanical means, springs, or fluid cushions.

Source: The OHIO State University

(1) Lower section of die on which the part nests. Also called an adapter, boss, horn, locator, master, master plug, and stool. (2) Guide post where wear plates are attached.

Source: The OHIO State University

A casting of a die impression made to confirm the accuracy of the impression.

Source: The OHIO State University

The radius on the exposed edge of a deep-drawing die, over which the sheet flows in forming drawn shells.

Source: The OHIO State University

(1) The 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. (2) Two (or, for a mechanical upsetter, three) machined dies used together during the production of a die forging.

Source: The OHIO State University

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.

Source: The OHIO State University

The maximum space (volume), or any part of the maximum space, within a press for mounting a die.

Source: The OHIO State University

The general term for a sheet metal part that is formed, shaped, or cut by a die in a press in one or more operations.

Source: The OHIO State University

(1) The stretching of a relatively small, shallow indentation into sheet metal. (2) In aircraft, the stretching of metal into a conical flange for a countersunk head rivet.

Source: The OHIO State University

A small unwanted mark or dimple in a completed part. Usually caused by dirt or material in the die.

Source: The OHIO State University

Any deviation from a desired contour or shape.

Source: The OHIO State University

A cam driver designed to ensure positive cam-slide travel in both directions.

Source: The OHIO State University

A drawing compound used to lubricate the stock during a forming operation.

Source: The OHIO State University

A die in which pressure is first applied to a blank through the blank holder and is then applied to the punch

Source: The OHIO State University

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.

Source: The OHIO State University

A round pin, usually case hardened, that fits into a corresponding hole to align two die members.

Source: The OHIO State University

The taper given to a die so as to allow the part to fall through the die or be removed.

Source: The OHIO State University

An insert or rib-like projection on the draw ring or hold-down surfaces that aids in controlling the rate of metal flow during deep draw operations. Draw beads are especially useful in controlling the rate of metal flow in irregularly shaped stampings.

Source: The OHIO State University

A specific type of form die that basically involves forcing the flat sheet of metal into a die cavity with a punch while holding the workpiece around the cavity to control metal flow.

Source: The OHIO State University

Impressions such as scratches, burnished areas, and similar marks left on the surface of the workpiece, part, or panel by a draw die. Also called skid marks.

Source: The OHIO State University

A circular plate with a hole in the center contoured to fit a forming punch; used to support the blank during the forming cycle.

Source: The OHIO State University

The radius at the edge of a die or punch over which sheet metal is drawn.

Source: The OHIO State University

The part of a draw die which holds the workpiece against the blank holder in which the metal is drawn over the inner edge by the punch.

Source: The OHIO State University

The forging operation in which the length of a metal mass (stock) is increased at the expense of its cross section; no upset is involved. The operation includes converting ingot to pressed bar using "V," round, or flat dies.

Source: The OHIO State University

(1) A measure of the feasible deformation of a blank during a drawing process. (2) Percentage of reduction in diameter of a blank when it is drawn to a shell of maximum practical depth. (3) The general formability and ductility of a metal.

Source: The OHIO State University

A term used for a variety of forming operations, such as deep drawing a sheet metal blank; redrawing a tubular part; and drawing rod, wire, and tube. The usual drawing process with regard to sheet metal working in a press is a method for producing a cup-like form from a sheet metal disk by holding it firmly between blank holding surfaces to prevent the formation of wrinkles while the punch travel produces the required shape.

Source: The OHIO State University

A substance applied to prevent pickup and scoring during deep drawing or pressing operations by preventing metal-to-metal contact of the workpiece and die. Also known as die lubricant.

Source: The OHIO State University

Ductility is a measure of the extent to which a metal can be deformed plastically before fracture. It is commonly defined by two parameters

Source: The OHIO State University

A unshaped device for tying sections of dies together either by design or to repair a die which has been broken.

Source: The OHIO State University

Portion of a press cycle during which the movement of a member is zero or at least insignificant. Usually refers to (1) the interval when the blankholder in a drawing operation is holding the blank while the punch is making the draw or (2) the interval between the completion of the forging stroke and the retraction of the ram.

Source: The OHIO State University

A cam that can be moved into position and held there while the press continues its cycle.

Source: The OHIO State University