Tool & Die & Metal Stamping Glossary

• Bend Allowance — The arc length of the neutral axis through a bend, added to the flange lengths to find the flat blank length.
• Bend Deduction — The amount subtracted from the sum of two flange outside dimensions to get the flat blank length.
• K-Factor — A ratio (0–0.5) locating the neutral axis within the material thickness during bending.
• Neutral Axis — The layer within a bent material that is neither stretched nor compressed.
• Springback — The elastic recovery of metal after a bending force is removed, opening the bend slightly.
• Punch Force — The force required to shear a slug or blank from sheet metal during piercing or blanking.
• Die Clearance — The per-side gap between punch and die that controls cut-edge quality and tool life.
• Shear Strength — The stress at which a material fails in shear; the key input to cutting-force calculations.
• Blanking — A press operation where the cut-out piece (the blank) is the usable part and the strip is scrap.
• Piercing — A press operation that punches a hole; the removed slug is scrap and the strip is the part.
• Progressive Die — A stamping die with sequential stations that progressively form a finished part as the strip advances.
• Compound Die — A die that performs multiple operations (e.g., blank and pierce) in a single press stroke at one station.
• Transfer Die — Tooling where the part is mechanically moved between separate die stations rather than carried on a strip.
• Strip Layout — The plan of how a part is oriented and progressed along the coil to balance utilization and feasibility.
• Pilot — A pin that engages pierced holes to precisely register the strip at each station of a progressive die.
• Stripper Plate — The plate that strips the material off the punches after the cutting stroke.
• Shut Height — The distance between the press bed and ram at the bottom of the stroke; must match the die closed height.
• Shear Angle — An angle ground onto a punch or die face so the cut occurs progressively, lowering peak tonnage.
• Center of Pressure — The point where the resultant of all cutting forces acts; it should align with the press ram centerline.
• Deep Drawing — A forming process that draws a flat blank into a hollow cup or shell deeper than its diameter.
• Draw Reduction Ratio — The proportional reduction in diameter taken in a single draw stage; limited to avoid tearing.
• Blank Holder — The pressure ring that controls metal flow into a draw die to prevent wrinkling.
• Wrinkling — A draw defect where compressive flange stresses buckle the metal into folds.
• Earing — Wavy height variation around a drawn cup caused by planar anisotropy of the sheet.
• Coining — A high-pressure forming operation that plastically sets material to a precise shape or thickness.
• Burr — The sharp raised edge left on the fracture side of a sheared or punched edge.
• Cut Edge Zones — The rollover, burnish, fracture, and burr regions that make up a sheared edge.
• Die Spring — A heavy-duty rectangular-wire spring color-coded by load class, used to power strippers and pads.
• Nitrogen Gas Spring — A self-contained cylinder using pressurized nitrogen to deliver high, near-constant force in a small package.
• Tonnage — The force capacity of a press, or the force a given operation demands, expressed in tons.
• Reverse Tonnage — The snap-through shock load that recoils into the press when a cut breaks through.
• Progression — The fixed distance a strip advances each stroke in a progressive die; equals the part pitch.
• True Position — A GD&T control defining the allowable location deviation of a feature as a diameter tolerance zone.
• Tolerance Stack-Up — The cumulative effect of individual tolerances across a dimension chain in an assembly.
• Hardness (Rockwell C) — A measure of a material’s resistance to indentation; HRC is the scale used for hardened tool steel.
• Air Bending — Press brake bending where the punch presses the sheet into a V-die without bottoming, setting the angle by depth.
• Bottoming — Bending that presses the sheet fully against the V-die, setting a sharper, more repeatable angle than air bending.
• V-Die Opening — The width of the V in a press brake die; the single biggest driver of bending tonnage and minimum radius.
• Draw Bead — A raised rib in a draw die that adds restraining force to control metal flow into the cavity.
• Ironing — A drawing operation that thins and smooths a cup wall to a precise, uniform thickness.
• Galling — Adhesive wear where material transfers and seizes between the workpiece and tooling, scoring the part.
• Work Hardening — The increase in strength and hardness of metal as it is plastically deformed during forming.
• Tensile Strength — The maximum stress a material withstands while being stretched before it fractures.
• Yield Strength — The stress at which a material begins to deform permanently rather than springing back.
• Grain Direction — The orientation of a rolled sheet’s grain, which affects bendability, springback, and earing.
• Annealing — A heat treatment that softens metal and restores ductility by relieving work hardening.
• Slug Pulling — A piercing defect where the cut slug sticks to the punch and is carried back up into the strip.
• Maximum Material Condition — The GD&T condition where a feature contains the most material — largest pin or smallest hole.
• Datum — A reference feature from which GD&T measurements and tolerance zones are established.
• Knockout — A mechanism that ejects a formed part or slug from the die so the cycle can repeat.
• Pressure Pad — A spring- or nitrogen-loaded plate that holds material flat during forming and strips or ejects it after.