METAL STAMPING DIE TERMINOLOGY
Air hardened - A quenching method used to cool tool steel. Air or a vacuum cools the steel slowly.
Annealing - heating steel and maintaining the temperature, then cooling gradually. This removes stress and hardness. Commonly performed to aide in forming.
Blankholder - a mechanism that prevents a blank from moving during a draw process
Blanking - process to form, cut or punch out a rough shape of sheet metal. The resulting part is called a blank.
Bolster plate - a plate attached to the press bed that locates and holds the die shoe in place.
Case Hardening - hardening to a pre-determined depth to improve wear resistance and strength for low carbon steel.
Clearance - the space between punch and die. Proper die clearance is important to maintaining press speed, minimizing tool wear, and minimizing punch point galling.
Die button - also called a die bushing, is a tube or sleeve that makes the opening for a piercing punch. The slug passes through the die button.
Die retainer - A hardened steel block that contains the impressions or cavities that shape the part as the punch descends, and also holds the die button.
Die shoe - also referred to as a die holder. A lower die shoe is the lower plate of a die set that supports the die retainer and die button. The upper die shoe is the upper plate of a die set that secures the punch retainer.
Flatness - a geometrical tolerance sometimes required, is measured as the distance between two parallel planes within which the entire surface of the part must lie. A flatness measurement determines the degree, if any, of variation in the surface of a part.
Guide post (or guide pins) - a steel rod positioned in the lower die shoe that fits into a bushing in the upper die shoe to guide the punch during operation, allowing precise alignment. The guide post bushing is a steel tube that directs the upper die shoe.
Hardness - a measure of wear resistance.
Heat Treat - heating process used to optimize tool steel properties. The process makes specific changes to the metallurgic structure. Very specific processes of heating, tempering and quenching significantly benefit a tool steel’s properties.
Knock out - A punch that ejects the part in a form die.
Lifter - a feature that lifts the part stock over lower tooling features as the stock is conveyed through a progressive die.
Oil hardened - A quenching method used to cool tool steel. Oil cools the steel at a moderate rate.
Pilot - a long slender punch that enters the part stock before other tools form the metal, to assure station to station alignment.
Pressure Pad - a metal pad or plate loaded with a gas spring or high pressure coils. A pressure pad is used to tightly hold metal being processed to the lower die shoe before the forming punch strikes.
Punch - the tool attached to the upper die set that forms or penetrates the part stock
Punch retainer - a device used to mount the punch on the upper die shoe.
Rockwell - a measurement of hardness used by heat treaters. Expressed as RC followed by the hardness number.
Secondary operations - treatments performed after the initial metal stamping process. Cleaning, heat treating, plating or deburring.
Shut height - the vertical measurement from the ram nose (top of the press bed) to the bottom of the bed where the bolster plate sits, when the ram is fully closed.
Stop block - a block used to act as a reference point for the height of the tool set up.
Strength - a measure of resistance to deformation. Often confused with hardness, which relates to surface resistance to wear, not formability.
Stripper plate - a thin plate designed to surround a punch that strips the scrap from the punch.
Stripping - the process of a punch retracting from a die after penetrating part stock.
Stripping force - the force required to drive a punch through part stock. Stripping force is determined by many factors including type of material, lubricant, sharpness of punch, and punch side wall finish.
Tempering - a heat treat process, after quenching as the steel cools the steel is reheated at a lower temperature to remove brittleness. Although the process reduces hardness the toughness is increased.
Water Hardened - a quenching method used to cool tool steel. Water cools the steel quickly.
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