Z94.12.4 Metal Forming

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CAMBER. A slight convexity or rounding of sheet, strip, or plate as might appear along the edge.

CAPACITY, PRESS. The rated force that a press is designed to exert at a predetermined distance above the bottom of the stroke of the slide.

CARBONITRIDING. A process in which a ferrous alloy is case hardened by first being heated in a gaseous atmosphere of such composition that the alloy absorbs carbon and nitrogen simultaneously, and then being cooled at a rate that will produce desired properties.

CARBON STEEL. Steel that owes its properties chiefly to the presence of carbon without substantial amounts of other alloying elements; also termed "ordinary steel,'' "straight carbon steel,'' "plain carbon steel.''

CARBURIZING. A process that introduces carbon into a solid ferrous alloy by heating the metal in contact with a carbonaceous material - solid, liquid, or gas - to a temperature above the transformation range and holding at that temperature.

CASE HARDENING. A process of hardening a ferrous alloy so that the surface layer or case is made substantially harder than the interior or core.

CHARPY TEST. A pendulum type of impact test in which a specimen, supported at both ends as a simple beam, is broken by the impact of the falling pendulum.

CIRCLE-GRID ANALYSIS. The analysis of deformed circles to determine the severity with which a sheet metal blank has been stretched.

CLOSED DIES. Forging dies in which the compressive force is applied to the whole surface of the forging. In open dies, there is no constraint to lateral flow in some directions.

CLOSED HEIGHT. (See SHUT HEIGHT.)

CLUTCH. An assembly connecting the flywheel to the crankshaft, directly or through a gear train; when engaged, it imparts motion to the mechanical power press brake ram.

COINING. A process of impressing images or characters of the die and punch onto a plane metal surface.

COLD WORK. Plastic deformation at such temperatures and rates that substantial increases occur in the strength and hardness of the metal. Visible structural changes include changes in grain shape and, in some instances, mechanical twinning or banding.

COLD WORKING. Deforming a metal plastically at such a temperature and rate that strain hardening occurs. The upper limit of temperature for this process is the recrystallization temperature.

COMPRESSIVE ULTIMATE STRENGTH. The maximum stress that a brittle material can withstand without fracturing when subjected to compression.

COMPRESSIVE YIELD STRENGTH. The maximum stress that a metal subjected to compression can withstand without a predefined amount of deformation.

CONTINUOUS OPERATION. Uninterrupted multiple strokes of the crosshead without intervening stops at the end of individual strokes.

CREEP. The flow or plastic deformation of metals that are held for long periods of time at stresses lower than the yield strength. Creep effect is particularly important when the temperature of stressing approaches the metal's recrystallization temperature.

CRIMPING. A forming operation used to set down, or close in, a seam.

CROWN. The upper part (head) of a press frame. On hydraulic presses, the crown usually contains the cylinder; on mechanical presses, the crown contains the drive mechanism.

CUPPING. The breaking of wire with a cup fracture accompanied by very little reduction of area; observed during cold drawing. Also the forming of sheet into cuplike objects such as shells, by deep drawing.

CURLING. Rounding the edge of sheet metal into a closed or partly closed loop.

CUSHION, DIE. An accessory for a press that provides a resistive force with motion required for some operations, such as blankholding, drawing, or redrawing, maintaining uniform pressure on a workpiece, and knocking out or stripping. Also called pads or jacks. Usually mounted in /under the press bed, they are also used in/on the slide.

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