Metal Forming Glossary


Abrasion Resistance
Ability of a coating to withstand rubbing, scraping and eroding forces.

Sharp mineral particles, used for metal removal.

Abrasive Media
Matrix used to carry the mineral particles for the purpose of material removal.

Acidic Etching
Removal of surface contamination by corrosive treatment.

A block used to mount a form tool to a slide.

Air Bending
Forming operation in which a metal part is formed without the punch and die closing completely on the part.

Air Hardening Steel
An alloy steel which will form martensite with high hardness when cooled in air from its proper hardening temperature.

Base metal with other metal or non-metal constituents melted together into a new molecular structure.

Commercial trade name for a chromate conversion coating over aluminum.

Aluminum Alloy
Pure aluminum which has been melted together with other constituents to achieve specific physical and mechanical properties.

Aluminum Oxide
Hard mineral of aluminum and oxygen (AI03) used as an abrasive.

Softest possible state of any material. Annealing is a full-heat treating process wherein metal is heated to a temperature above its critical range, held at that temperature long enough to allow full recrystallization, then slowly cooled through the critical range. Annealing removes working strains, reduces hardness, and increases ductility.

Positively charged electrode.

Process of applying a controlled oxide layer to the surface of aluminum.

The storage of files in the form of tape or disk for long periods of time.

Partial circles used to describe rounded corners of material and show bends in material. Artificial age-hardening process of material accelerated by temperature.

Acronym for “American Standard Code for Information Interchange.”

A heat treating operation in which austenite is quenched to and held at a constant temperature (usually between 450°F and 800°F) until transformation to bainite is complete. In some steels at certain hardness levels, bainite is tougher than quenched and tempered structures.

The solid solution in which gamma iron is the solvent. Austenite is a structure and does not refer to composition. Austenite is the structure from which all quenching heat treatments must start.

A non-magnetic stainless steel that is not hardenable through heat treatment; demonstrates good corrosion resistance.

A brand name of CAD software prevalent in the marketplace.

Automatic Spinning
The art of forming metal over a mold using an automatic (Computer Controlled or Template) spinning lathe.


Back Gauge
Stop located in the rear of a metal forming or fabricating machine which is used to position the workpiece during an operation.

Banding, Metallic or Non-Metallic
Strong, lightweight ribbons, generally of steel or nylon, applied under tension to strap packages on a pallet.

Bar Coding
Machine-readable alphabetic and/or numeric information used for identification of packaged parts.

An older term used to describe the decarburized skin that develops on steel bars heated in a non-protective atmosphere.

Barrel Tumbling
Process in which parts to be deburred are put together with abrasive material into a many-sided barrel and slowly rotated for prolonged periods for the purpose of burr removal.

See “Primer.”

Bottom transverse structural member on metalforming machine.

Belt Sanding
Metal removing process in which an abrasive impregnated endless cloth belt does the cutting.

Bend Radius
Inside radius of a formed feature.

Bend Relief
Clearance notch at an end of a flange to allow bending without distorting or tearing adjacent material.

Generally applied to forming. Creation of a formed feature by angular displacement of a sheet metal workpiece. See also “Drawing” and “Forming.”

Refers to surfaces which meet at an angle in different planes.

Acronym for “bits into sound.”

(1) Sheet metal stock from which a product is to be made. (2) Workpiece resulting from blanking operation.

Die cutting of the outside shape of a part.

Leaching of entrapped plating solutions, causing surface discoloration and corrosion.

Blind End Fastener
Internally threaded fastener which is manufactured with one end closed such that, when installed, it forms a gas and moisture resistant seal.

Blind Fastener
Fastener which is capable of being permanently installed and used in a workpiece with access from only one side.

Blind Rivet
Rivet which is capable of being installed and used in a workpiece or assembly with access from only one side.

Forming operation in which the punch and the die is closed completely on the workpiece.

Bow Distortion
Out-of-flatness condition in sheet material commonly known as “Oil Canning” in which, with the edges of the sheet restrained, the center of the sheet can be popped back and forth but cannot be flattened without specialized equipment. This condition is sometimes inherent in the material as received from the supplier and sometimes the result of multiple punching or forming operations.

Acronym for “bits per second.” Refers to the rate at which a data communications line can transfer information. Bits per second can be faster than baud rate when data compression is used.

Alloy of copper and zinc.

See “Breakout.”

Fractured portion of the cross section of a cut edge of stock. A condition naturally occurring during shearing, blanking, punching and other cutting operations.

See “Micro Ties.”

Bright Annealing
Annealing work in a protective atmosphere to prevent discoloration as the result of heating. In some atmospheres oxides may be reduced.

Brinnell Hardness Testing
A method of testing the hardness of material. This test is usually used on softer materials and castings in which a carbide ball is pressed into the material for a given period of time and then removed. The resulting impression is measured for the width along with a value determines hardness of the material.

Brushing or Etching
Mechanical or chemical cleaning of parts before further processing.

Polishing method employing soft cloth to carry very fine polishing compounds.

Burn Mark
Heat discoloration created in the contact area of a welding electrode.

Smooth or shiny area above the breakout on a sheared edge. Also called shear or cut band.

Raised, sharp edge inherent in cutting operations such as shearing, blanking, punching and drilling.

Burr Direction
Side of the stock on which burrs appear.

Burr Height
Height to which burr is raised beyond the surface of the material.

Burr Rollover
Condition of burr displacement resulting from mechanical debarring operation.

Edge without sharp protrusions.

Bus Bar Copper
Copper with minor alloying constituents and high conductivity; used for electrical applications.

End to end.


Acronym for “Computer Aided Design.”

Cadmium Plating
Electrolytic process for metal coating in which commercially pure cadmium is the anode.

Acronym for “Computer Aided Manufacturing.”

A device used to control the motion of slide forming machine slides, attachments and die components

Cam Chart
A chart created by the tool designer assuring that the sequence of operations of a complicated part fall within the 360 degree slide forming machine cycle.

Cam Trim
Removing excess material after the part has been drawn or formed. This is done with a cam activated operation, usually as a secondary operation.

Gradual deviation from straightness of the edge of sheet or coil stock caused during the slitting operation.

Capillary Action
Liquid trapping action caused by the closeness of two surfaces and the surface tension of the liquid.

Carbon Steel
Steel which owes its properties chiefly to various percentages of carbon without substantial amounts of other alloying elements.

A heat treatment for steel which adds carbon and nitrogen from an atmosphere rich in such elements.

Adding carbon to the surface of steel by heating it in contact with carbon rich gases.

The surface layer of a steel whose composition has been changed by the addition of carbon, nitrogen, or other material at high temperature.

Case Hardening
A heat treatment in which the surface layer of a steel is made substantially harder than the interior by altering its composition.

Negatively charged electrode.

Cellular Dividers
Slotted cardboard sheets designed to be interleaved in a master carton producing individual pockets to separate parts.

The point which is defined midway between the extents of a hole in both the X and Y directions.

Center Tool
See mandrel.

Chain Dimensioning
Drafting practice which dimensions repetitive features from each other rather than a common datum.

Surface ripples and cracks induced by torming.

Chemical Etching
Removal of metal through chemical erosion process.

Post-treatment wash (non electrolytic) coating which is used over zinc, cadmium-treated aluminum, and other plating operations to seal the surface of the coating, prevent oxidation and, in certain cases, improve the electrical characteristics of the coating. May be cleat yellow or blue to visually indicate that the product has been coated.

Chromate Conversion
Application of a salt or ester of chromic acid to a metal workpiece by dipping or spraying. The coating is generally used to seal the surface of the workpiece to enhance electrical properties or reduce corrosion.

A continuous arc starting and ending at the same point.

Clad Shape
A roll formed shape made up of two materials simultaneously fed into the roll forming mill to produce a composite section.

Clamp Marks
Slight indentations at the edge of one side of stock caused by pressure from turret press holding devices. See also “Workholder Mark.”

Clinch Fastener
See “Inserted Fastener.”

Clock-Spring Material
Alloy steel available in a pre-hardened condition between RC 45 and 52.

Industry acronym for “Computer Numerical Control.”

CNC Turret Press
Automatic punch press indexing the material and selecting the intended tool out of the rotary tool holding device (turret) totally by computer control for piercing, blanking and forming workpieces as programmed.

Paint, varnish or lacquer applied to a surface in a single application (one layer) to form a properly distributed film when dry.

Coating System
Consists of a number of coats separately applied in a predetermined order at suitable intervals to allow for drying or curing.

Process in which the customer and the supplier review and modify a design to simplify manufacturability of a part.

Coil Breaks (Crossbreak)
Defective condition of ridges or marks across the width of sheet or coil caused by improper coiling or leveling.

Compressive metal flowing action. See also. “Bottoming.”

Cold Rolled Steel
Steel which was reduced to final thickness in the cold state by a rolling mill. Creates a smooth surface with slight skin hardness.

Cold Weld
Defective weld due to improper contact or inadequate heat during welding.

Cold Worked
Material hardened naturally through forming at ambient temperatures.

Cold Working
Plastic deformation of a metal at a temperature low enough so that recrystallization does not occur during cooling.

Collapsible Tool (Segmented)
A “mold” having a removable center core which keeps the perimeter pieces in place during spinning.

One aspect of appearance; a stimulus based on visual response to light, and consisting of the three dimensions of hue, saturation, and lightness.

Color Chips
Paint samples.

Color Match
Pair of colors exhibiting no perceptible difference when observed under specified conditions.

Commercial Grade
Standard materials commonly available through supply houses.

Communications Software
A computer program that enables one computer to connect with another computer.

Compound Die
Tool used to pierce, form and blank a part at the same time, with one stroke of the press.

To condense electronic files for ease of transfer and storage.

Dimensional relationship of 2 or more items sharing a common center line.

Having all elements, features, dimensions or functions existing in one geometric plane.


Die Cushion
Large pressurized cylinder, generally housed beneath the bed of a press which is used to apply upward pressure to the lower die.

Die Cut Inserts
Packaging elements, generally of cardboard, which are machine blanked to a specific shape in order to precisely fit a part contour.

Die Marks
Scratches, scrub marks, indentations, galling or burnishing of sheet metal workpieces by tooling.

A measurement describing size and/or appearance of a part feature.

Dip Brazing
Metal bonding of parts by molten bath immersion.

(1) Staining. (2) Changing or darkening in color from the standard or original.

A flexible plastic disk coated with magnetic oxide and used for storing electronic data.

Double Action
Press utilizing two moving elements.

Double Burned
A condition that may occur on a laser wherein the laser essentially produces a feature twice destroying the part’s edge and causing out of dimension condition.

To receive data from another computer.

Drain Holes
Holes placed in the part that are nonfunctional except to allow for drainage.

A term used interchangeably with tempering in the heat treating process.

Draw Ring
Holding device in a die to control material flow and wrinkling during forming.

(1) Engineering document depicting a part or assembly (2) In metal forming, the stretching or compressing of a sheet metal part into a die so that it can be punched to create a three-dimensional part.

Dry Film Thickness
Thickness of an applied coating after drying or curing.

Dry Spray
See “Oversprays.”

Ability of a material to be bent or otherwise formed without fracture.

Dutch Bend
See “Hem.”


Early Supplier Involvement
Evocation of the supplier during the conceptual development stage of a product.

A transition between surfaces.

Edge Bulge
Condition resulting from any forming, piercing, hardware insertion or spot welding operation too close to an edge.

Edge Deckle (Mill Edge)
Waviness of an unslit coil edge, as received from the material supplier.

Edge Pucker
Material extrusion beyond an outside edge through metalforming.

A dimension between the edge of the part and a feature.

Effective Case Depth
The perpendicular distance from the surface of a hardened case to the deepest point at which a specified level of hardness is attained.

(1) In welding, a tungsten rod (TIG) or consumable metal wire (MIG) that is used as an electrical conductor at the point between the welding torch and the workpiece. (2) In spot welding, the upper and lower shaped conductive elements between which two or more sheet metal parts are squeezed, and through which current flows during resistance welding.

Electrolytically Deposited
Depositing of one material on another (commonly known as plating).

Electron Beam Welding (EBW)
Melting and fusing of metals by use of a collimated stream of electrons traveling at close to the speed of light. The kinetic energy from the electrons converts to heat on impact.

Deposition of a thin layer of metal to a workpiece using an electrolytic process.

Electrostatic Spraying
Method of spray painting in which an electrostatic potential is created between the article and atomized paint particles. The charged particles of paint are attracted to and deposited on the articles being painted. The electrostatic potential is used in some processes to aid the atomization of the paint.

Electronic mail.

Enclosed Seam and Pocket
Formed, spot welded or welded area that can entrap plating solutions.

End Flare
Seen after cut off; caused by the release of residual forming stresses in material being roll formed where one longitudinal end spring is open and the other spring is closed.

A predefined element that you place in a drawing by means of a single command. A single piece of geometry or text.

Environmental Testing
Testing of a product or finish for resistance to attack by specific elements.

See “Chemical Etching.”

An executable suffix to a computer file denoting it as an execution file.

Extruded Hole
Pierced and formed hole in sheet metal in which the metal has been stretched creating a tubular shape.


Feather Edge
Material thinning toward an edge, creating an irregular knife-edge, “tattered” appearance.

Dimension between two features on a part.

Feed Eccentric
A screw-adjusted device used to set the feed length on a slide forming machine.

Feed Unit
An integral part of the slide forming machine, eccentric-driven and cam controlled, that advances either wire or strip in accurate increments.

Female Tool
A “mold” duplicating the exterior dimensions of the part.

Referring to iron content.

Ferro Magnetic
Various alloys that exhibit magnetic qualities.

Metals containing iron as a major alloying constituent.

File Names
A name assigned to a computer file.

Fillet Weld
Joining method of filling an inside edge with welding metal.

Degree of physical match between two or more components.

Tooling designed to locate and hold components in position.

Flame Hardening
A process consisting of heating a desired area, usually localized, with an oxyacetylene torch or other type of high temperature flame and then quenched to produce a desired hardness.

Formed projection or rim of a part generally used for stiffness or assembly.

Flat or Matte
Coating surface which displays no gloss when observed at any angle; a perfectly diffused reflecting surface.

Flat Pattern
A two-dimensional development that represents the part before it is formed into a three dimensional shape.

Flat Wire
Round wire which has been reduced to a flat state with rounded edges.

Floating Fastener
Hardware which allows the threaded portion to move within its particular confines without rotating, to compensate for misalignment.

Floppy Disk
See “Diskette.”

Flower Diagram
A drawing which superimposes the cross section contour of a roll formed part at each roll station, starting with the flat incoming material and ending with the desired profile. It depicts the anticipated flow of material in the forming process.

Series of rounded parallel grooves that shows on the surface of metals.

Flying Die Cutoff
The system used in roll forming to cut the formed shape to length in a continuous operation. Similar in action to a punch press, but designed to allow the die to move in line with the roll formed shape during the cutoff cycle, and to make a cut on the fly based on a signal from a trigger mechanism.

Follower Block (Tail Block)
This serves to clamp the work piece to the tool.

Foreign Matter
Anything visually unrelated to the true nature of the substance under examination.

A bend, or the process of bending a metalformed part.

Form Lifter
A cam-operated motion used for lifting the mandrel or forming in an opposite plane.

Formed Tab
Small flange bent at an angle from the body of a metal workpiece.

Operation converting a flat sheet metal workpiece into a three dimensional part. See, also “Bending” and “Drawing.”

Forming Slides
Cam operated units used to drive tools on a slide forming machine.

Forming Tool
A slide mounted tool used for bending on a slide forming machine.

Dimension between two forms on a part.

Fourslide Machine
A machine, either horizontal or vertical, used to fabricate formed metal stampings and wire forms, by the action of four forming slides acting upon a stationary mandrel or center tool.

Front Cut-Off
A device driven by a cam that is mounted on the front shaft of a slide-forming machine; used to sever the blank from the strip before forming.

The degree to which the designed part will perform to meet its intended purpose.

Fuse Welded Joint
Welding method without addition of a filler metal, used to generate little, if any eruption above the original surface level.


See “Gauge” definition (1).

Galvanic Corrosion
Dissimilar metals in contact with each other in presence of moisture, acting as a battery and causing an electrolytic etching deteriorating effect.

See “Nesting.”

Gas Metal Arc Welding (GMAW)
See “MIG Weld.”

Gas Tungsten Arc Welding (GTAW)
See “TIG Weld.”

Gas Welding
Melting and fusing metals together by use of an oxygen and flammable gas mixture.

(1) Instrument for measuring, testing, or registering. (2) Numeric scale for metal thickness.

See “Master Carton.”

Subjective term used to describe the relative amount and nature of mirror-like (specular) reflection.

Instrument for measuring the degree of gloss in relative terms. Such instruments measure the light reflected at a selected specular angle. Go/No-Go Gauge -Measuring device with two registration elements which determine if a feature to be measured is between two established limits.

Go/No-Go Gauge
Measuring device with two registration elements that determine if the feature being measured is between two established limits.

Surface imperfection, deeper than a scratch, often with raised edges.

Grain Direction
(1) Crystaline orientation of material in the direc ion of mill rolling. (2) Orientation of a surface finish generated by abrasive method.

Process of removing material by abrasion.

Material clamping devices often serrated for additional holding force to restrain material during a die operation.

Mineral particles used for abrasive metal removal.


Half Shearing
Partial penetration piercing, creating a locating button with a height of about 1/2 material thickness.

Hard Tooling
Tooling made for a specific part. Also called “dedicated tooling.”

The fundamental characteristic of a steel which determines the ease of preventing the transformation of austenite to anything else but martensite during the quench.

(1) The physical components of a computer system. (2) Fasteners inserted into a sheet metal part.

Hardware List
Information that should be conveyed to the part supplier specifying part numbers, description and quality of fasteners.

Heat Sink
Good thermal conductor used to remove destructive heat from an area.

Hem (Dutch Bend)
Edge of material doubled over onto itself for the purpose of safe handling or to increase edge stiffness.

Hold-Down Marks
Slight indentations or scuff marks on one side of the stock which can result from the pressure of hold down devices during shearing operations.

Hole Rollover
Rounding of the top edge of a pierced feature caused by the ductility of the metal, which flows in the direction of the applied force.

Dimension between the center of a hole and another feature.

Distance from the center line of a hole to the edge of a formed feature.

Dimension between centers of holes.

An annealing treatment at a fairly high temperature designed to eliminate or reduce chemical segregation.

Host Computer
An unattended computer that can be accessed by other (remote/client) computers.

Hot Dip
Application of a metal coating on a substrate by immersion in a molten metal bath.

Hot Rolled Steel
Steel which was rollerformed from a hot plastic state into final shape; characterized by a rough, scaly surface.

Acronym for “Hewlett Packard Graphics Language.”

(1) Attribute of a color by means of which a color is perceived to be red, yellow, green, blue, purple, etc. White, black and grays possess no hue. (2) The name of a color of a finish, as viewed subjectively.

Hydraulic Press
Machine which exerts working pressure by hydraulic means.

Hydrogen Embrittlement
Loss of ductility of a material due to absorption of hydrogen gas during heat treatment an electrolytic process or during acid cleaning.


Acronym for “Initial Graphics Exchange Specification.”

Impact Resistance
Ability to resist deformation from impact.

Inboard Mill
A roll forming machine with a housing only on one end of the roll tooling shaft.

Particles of impurities (usually oxides, sulphides, or silicates) which separate from the liquid steel and are mechanically held during solidification. In some grades of steel, inclusions are made intentionally high to aid machinability.

Indexable Tool Stations
Special tool positions in a turret press which are equipped with numerically controlled servo drives rotating the punch and die together to profile contours, nibble angles or for other special applications.

Inductance Instrument
Instrument which is used to measure thickness of applied coatings to metal substrates. Unlike magnetic thickness gauges. inductance gauges can measure either conductive or non-conductive coatings on magnetic or non-magnetic substrates.

Induction Hardening
A form of hardening in which the heating is done by induced electrical current.

See “Inserted Fastener.”

Inserted Fastener
Pins, nuts, studs, standoffs or other special hardware that are inserted into a specifically punched hole on the work piece.

Inside Radius
See “Bend Radius.”

Inspection Criteria
Characteristics by which the part will be evaluated both dimensionally and cosmetically.

Interrupted Quench
Stopping the cooling cycle at a predetermined temperature and holding at this temperature for a specific time before cooling to room temperature. Usually done to minimize the likelihood of cracking, or to produce a particular structure in the part.

ISO Drafting Standard
Regulation for the creation of technical drawings published by the International Organization of Standards.

Isothermal Treatment
A type of treatment in which a part is quenched rapidly down to a given temperature, then held at that temperature until all transformation is complete.


See Fixture.


King Post
See mandrel.


Lanced and Formed Tab
See “Formed Tab.”

Lap-Welded Joint
Welded seam in which the two metal pieces to be joined overlap one another.

Acronym for “Light Amplification by Stimulated Emission of Radiation.”

Laser Welding
Metal melting and fusing using the energy of a concentrated coherent light beam.

A CAD file is like a layered stack of clear transparency films with design information on the different layers. They are superimposed on each other. One can look down through all of the layers at once, or only selected layers.

Lead Screw
A screw specialized for the purpose of translating rotational to linear motion.

Lead Time
Time required to manufacture a product from order placement until availability. It includes planning, engineering, tool design and construction, acquisition of materials, scheduling, fabrication, finishing and packaging.

Leg Size
Width and height of the filler bead of welding material.

Lever Arms
A scissors-like apparatus used to apply pressure to the spinning blank.

Line Width
Thickness of a line in CAD drawings.

Linear Slide Machine
A vertical slide-forming machine with the ability to place several opposing slides, arranged in a linear fashion, on both the front and back sides of the tooling area. This provides the ability to produce complicated tampings and assemblies.

A straight line segment between two points.

Load Up
Accumulation and compaction of metal particles between the abrasive grit of a grinding belt disc or wheel rendering it ineffective.

Lock Seam Tube
A hollow (closed) roll form shape mechanically fastened using the roll form tooling.


Abbreviation used to designate a Macintosh computer; manufactured by Apple Computer.

Magnetic Thickness Gauge
Device, applicable only to ferrous substrates, which measures the thickness of non-conductive coatings.

Usually an object used to shape machined work. A shaped bar of metal is inserted into, or next to, an item being machined or bent in a certain pattern, creating smooth curves and preventing undesirable creasing kinking or collapsing.

Manganese (Mn.)
Lustrous redish-white metal of hard brittle and therefore non malleable character. Element number 25 of the periodic system. Atomic weight 54.93.

The degree to which a product can be efficiently and accurately produced using modern manufacturing methods.

Martempering or Marquenching
Martempering is a form of interrupted quenching in which the steel is quenched rapidly from its hardening temperature to about 450° held at 450° until the temperature is uniform, then cooled in air to room temperature. Actual hardening does not occur until the air cooling starts and is accomplished with a minimum temperature differential. Martempering is indicated for low to medium alloy steels when distortion may be a problem.

A terrific material with distinctive needle like structure which is always present in heat treat hardenable steel.

Martensitic Stainless Steel
Select group of 400 or 500 Series stainless steel which are magnetic and hardenable by heat treating.

Temporary shielding of a portion of a product to selectively prevent the application of a coating.

Master Carton
Large box, generally 42 in. wide, 48 in. long and 30 in. high, made from heavy test cardboard and designed to fit a standard pallet.

Master Die
Universal tool receptacle for holding changeable tool systems.

Master Document
An original file retained in case of subsequent errors to a copy.

Material Utilization
Extent to which optimal use of material is approached.

Mechanical Assemblies
Part combinations attached by mechanical means through the use of hardware.

Mechanical Fastener
Device clamping two or more components together by mechanical force, such as rivets, screws, etc.

Number of holes per inch in sieves used to tort mineral abrasive particles into specific grit sizes.

Metal Arc Weld
Metal melting and fusing process using a continuous metal consumable electrode with an inert gas around the electrode to shield against oxidation.

Metal Thinning
Thickness reduction during any forming operation.

Metameric Match
See “Conditional Match.”

Micro Alloying
Specific alloy combination usually designed for special strength, ductility or flexibility.

Micro Ties
Thin bridges of metal which are left to hold parts in place during turret punch fabrication.

MIG Weld (Metal Inert Gas) or GMAW (Gas Male Tool)
A “mold” duplicating the interior dimensions of the part.

Mill Edge
See “Edge Deckle.”

(1) Pre-production sample made with limited emphasis on tolerance to test a design concept. See, also, “Prototype.” (2) A computer graphic depicting exact geometry of a part.

A device used to transfer electronic files via telephone lines.

Mold Lines
Lines in a drawing connecting the inner radius and outer radius of a bend and showing the extent of bend.

Multiple Level Forming
A sequence of slide forming operations at different elevations of the center tool.


N/C Press
Numerically controlled press. See “CNC Turret Press.”

Numerically controlled.

(1) Grouping of identical or different parts in multiples within a workpiece to conserve material. (2) In packaging, stacking of parts whose shape permits one to fit inside another.

Nibble Marks
Slight irregularities at the edge of the stock surface after progressive punching (“nibbling”) operations in a turret press.

The process of adding nitrogen to the surface of a steel usually from dissociated ammonia as the source. Nitriding develops a very hard case after a long time at comparatively low temperature, without quenching.

The targeted value for a dimension that defines the size of an ideal part.

Non Ferrous Metal
Elements and their alloys without iron as a major constituent.

Information not related to the shape of the product. (i.e. part number, notes, material lists, tolerances, etc.)

Non-uniform Coverage
Inconsistent paint thickness.

The process of heating steel to a temperature above its transformation range, followed by air cooling. The purpose of normalizing may be to refine grain structure prior to hardening the steel, to harden the steel slightly, or to reduce segregation.

Operation in which the punch removes material from the edge or corner of a strip or blank.

Area melted together during resistance welding.


Contraction of the words oblong and round denoting a punched slot with semicircular ends and straight sides.

Observational Standard
See “Color Chips.”

Oil Canning
See “Bow Distortion.”

Orange Peel
Surface condition characterized by an irregular waviness of a paint finish. resembling an orange skin texture.

Orbital Sanding
Non-straight-line abrasive finish with irregular circular marks.

Organic Coating
Designation of any chemical finish containing carbon.

Orthographic Drawing
A drawing showing a projection of a part which all the features are visible.

Outboard Mill
A roll forming machine with housings that support both ends of the roll tooling shafts.

Outside Radius
Formed outside radius of a bend.

Overlapping Seam
See “Enclosed Seam and Pocket.”

(1) Spray material which may be lost within the spray booth or to the atmosphere. (2) Spray material which subsequently falls on the product. (3) Areas adjacent to coating of surfaces requiring paint.

Chemical reaction between a material and oxygen.

Oxidation Scale
Stained, discolored and flaky surface condition.


Wooden platform, generally 42 in. wide, 48 in. deep, and 6 in. high designed to facilitate lift truck handling of parts or packages.

Pancake Die
Simple push-through die for blanking or piercing.

Defining a feature’s size by establishing a geometric relationship between it and other features, instead of defining it with a dimension.

Pattern Direction
Orientation of features or surface patterns on sheets and coils.

Pem Fastener
Self-clinching inserted fastener (nut, stud, standoff, pin, blind standoff, etc.) made by Penn Engineering & Manufacturing Corp.

Pencil Hardness Test
Method to measure coating hardness based on the scratching of the film with pencil leads of known hardness. The result is reported as the hardest lead which will not scratch or cut through the film to the substrate.

(I) Depth of a cutting operation before breakout occurs. (2) In welding, the depth of material through which fusion occurs.

The extreme outer edge of part or drawing.

Dimensional relationship of a part or datum located at right angles (90′) to a given feature.

Pretreatment of steel or certain other metal surfaces by chemical solutions containing metal phosphates and phosphoric acid as the active ingredients, to form a thin, inert, adherent, corrosion-inhibiting chemical conversion coating which serves as a substrate for subsequent paint coats.

Phosphor Bronze
Copper base alloy with 3.5 to 10% of tin to which phosphorus has been added in a molten state in varying amounts of less than 1% for deoxidizing and strengthening purposes.

Pickled and Oiled
Hot rolled steel with the scale removed through immersion in acid and a follow up rinsing and oiling process for oxidation protection. Also referred to as “P&O” and HRPO.”

Punching of openings such as holes and slots in material.

Finely ground, natural or synthetic, inorganic or organic, insoluble particles that, when dispersed in a liquid vehicle to make paint, may provide color as well as other essential properties of a paint such as opacity, hardness, durability, and corrosion resistance.

Pinch Trim
Trimming excess material from a drawn part at the bottom of the stroke. Leaves drawn shell without an inside burr, but with an outside burr and a thinned edge.

Pitting (Inter-Crystalline Corrosion)
Galvanic attack under moist and acidic conditions between molecular structures of differing alloy content.

Plasma Arc Welding (PAW)
Specialized process utilizing a non-consumable electrode ionizing an inert gas and increasing temperature to melt the material being welded.

Plastic Deformation
Permanent deformation occurring in forming of metal after elastic limits have been exceeded.

Sheet steel thicker than 7 gauge 0.179 in. (4.55 mm) or sheet aluminum thicker than 3/16 in (4.76 mm).

A piece of geometry at an exact location.” Attached to that entry also is the term Polishing and its definition. Polishing should be called out separately and read: Abrasive process in which the surface created takes on a bright reflective finish, scratch-free to the unaided eye.

Postcut Roll Forming
A process whereby the raw material is fed into the roll forming mill in coil form with the formed part cut to length. This is the most common roll forming material feeding process.

Powder Coating
100‰ solids coating applied as a dry powder and subsequently converted into a film with heat.

Power Spinning
The art of forming metal over a mold in one pass using hand or hydraulic pressure.

Precipitation Hardenable
Alloy in which a constituent precipitates from its supersaturated solution allowing the material to gain added strength.

Precision Lead Screw
See “Lead Screw.”

Precut Roll Forming
A process whereby the raw material is cut to length prior to entering the roll forming mill and fed into the mill as blanks. Primarily used for low-volume applications.

Prefinished Material
Stock which has been painted or plated prior to fabrication or stamping.

A device used to stamp a hole or notch a pattern in incoming material on a roll forming line prior to roll forming.

Press Attachment
A bed mounted device on a slide forming machine used for punching, piercing and other press operations.

Press Section
A device that is built into a slide forming machine used for punching, piercing and other press operations.

First application of a substance capable of adhering to the substrate and providing good adhesion to a subsequent coating.

Programmable Back Gauges
Stops on metalforming machines which can be adjusted during and between cycles by computer numeric control.

Progressive Tool
Die using multiple stations or operations to produce a variety of options. Can incorporate piercing, forming, extruding and drawing, and is usually applied to high quantity production runs.

Projection Weld Nuts (or Studs)
See “Weld Nuts” and “Weld Studs.”

Projection Welding
Using protrusions on one of the two parts to be resistance welded creating a positive conductance path.

First part of a design which is made to test tolerance capability, tooling concepts and manufacturability.

Pull Down
Area of material next to the penetrating edge of a piercing punch, or die edge of the blanking station, where the material yields. i.e. flows in the direction of the applied force, creating a rounded edge. Also known as “rollover.”

Pulse Mode
Intermittant surging of laser cutting power action.

Punch Direction
The direction from which a tool or punch enters the workpiece.

Punch Press
Machine supplying compression force for reshaping materials.

Punch Side
Opposite side from burr side for pierced features; side on which the punch enters the material. The punch side is the burr side for blanked outside contours.


Cooling from high temperature, usually at a fast rate.

Quick Change Inserts
Tool sections or parts which may be changed without removing the entire tool from the press.


Driven (movable) part of a metalforming machine.

Rear Cut Off
A device on a slide forming machine driven by a cam that is mounted on the rear shaft allowing the removal of a slug from the strip thus providing the ability to produce a blank with special end shapes.

Operation in turret press fabrication denoting the release of the workholders, movement of the X axis to a new position on the workpiece, and the regripping of the workpiece so that a sheet larger than the X axis table travel can be fabricated, all under computer numeric control.

Extent to which parts from multiple lots are identical.

Final cold rolling operation, usually done to achieve specific thickness control and improved finish.

Natural or synthetic basic material for coatings and plastics.

Resistance Projection Weld (RPW)
See “Projection Weld.”

Resistance Spot Welding (RSW)
Melting and joining action of two adjoining metal surfaces created by the thermal reaction of the metal to the flow of an electrical current forming a weld nugget.

A subsequent part drawing usually denoting new corrected or improved version.

Revision Description
A written notice describing the nature of changes to a drawing.

Rivet Nut
Internally threaded fastener designed to be used as a rivet from one side of a workpiece or assembly and to provide threads for a screw or bolt to be used in assembly of a mating part.

Rockwell Hardness
An indentation hardness test based on the depth of penetration.

Roll Formed Shape, Hollow
A roll formed shape which is closed by mechanically fastening or a welding the two strip edges together.

Roll Formed Shape, Open
A roll formed shape with a linear or curved contour in which the two ends of the shape are not brought together.

Roll Forming
A continuous bending operation in which sheet or strip metal is plastically deformed along a linear axis by being passed through a series of roller dies and progressively shaped to the desired contour.

Roll Stations
Tandem sets of rolls used in roll forming to shape the metal stock in a series of progressive stages to form the desired cross-sectional configuration.

See “Pull Down.”

Rotary Slide Machine
A vertical forming machine with the ability to place several forming slides radially around the center tool and produce intricately formed stampings and wire forms.

Extent to which a feature is circular.

Sag or accumulation in a paint or finish film prior to curing.


(1) Thick oxide coating on material normally associated with hot working. (2) Deposit formed from solution directly in place upon a confining surface.

Edge condition resulting from nibbling a feature in a turret press.

Leftover, unused material relegated to recycling.

Selective Perforation
Hole or slot pattern over a specific portion of a workpiece, normally used for ventilation purposes.

Self Extracting Archive File
A library file that can automatically create a group of (CAD) files without requiring the operator to have any special knowledge, or use special software.

Self Fixturing
Part designed to be self-locating into proper position to another part with the use of built-in locators.

Self Locking Fastener
Fastener which is machined with interference threads or which has a nylon insert or other locking mechanism to securely hold mating fasteners in high torque or vibration applications.

A gloss range between high gloss and eggshell, approximately 35 to 90 on the 60 degree gloss scale.

See “Half Shear.”

Shake Aparts
Term designating a family of parts on a sheet which are held by “Micro Ties” so small that the parts can be removed from the sheet after CNC punching by simply shaking the sheet.

Shear Form
See “Lanced Tab.”

Shear Spinning
The art of forming metal over a mold in one pass using hand or hydraulic pressure.

Cutting force applied perpendicular to material causing the material to yield and break.

Shearing of an edge of stock to an exact dimension from an already existing feature.

Shielding Gas
Inert gas used for oxidation protection during welding.

Shim Steel
Steel which has been rolled thin to a hard condition and very close tolerance.

Short circuiting of a (weld) current through a previously applied weld nearby.

Shut Height
Clearance in a press between ram and bed with ram down and adjustment up.

Silicon Carbide
Mineral used for abrasive metal removal.

Printing process using special inks being pressed through a fine meshed fabric which has been prepared by a photo process to let the ink pass through in predetermined patterns of lettering and graphics.

Single Action
Press utilizing one moving element.

In welding, a dimple on the surface of stock caused by shrinking of the weld during cooling.

Skid Marks (Roll Slip)
Polished or burnished streaks across the stock surface resulting from improperly set roller driven material processing equipment. Skid marks are transverse to the direction of rolling.

Single cold rolling process on material after a heat treating process.

Slide Forming
A high-volume stamping process in which a machine with multiple slides sequentially performs various operations (i.e. blanking, piercing, forming, etc.).

Distance from a slot edge to the inside edge of a formed feature.

Scrap from a piercing operation.

Slug Marks
Surface defects caused by scrap being indented into the metal surface.

Soft Tooling
A term generally applied to the fabrication of metal parts using computer controlled technology incorporating CNC turret presses, laser profilers and press brakes.

The ability of the CAD software to realize that a volume is filled with solid matter. These CAD systems can display a design so that it looks like a solid object. Includes recognition of surfaces and wireframes.

Solution Heat Treat
High temperature process in which an alloy is heated to the suitable temperature for the alloy constituents to be in a totally soluble condition for the purpose of creating a homogeneous alloy. Through rapid cooling the constituents stay in this solution state. Metal so treated is left in a super saturated unstable state and may tend to age harden at ambient temperatures.

Solvent Based
Paint type in which a volatile liquid is used to dissolve or disperse the film forming constituents.

In welding, droplets of matter deposited as contaminants.

Adjective referring to spectrum. See “Spectrum.”

Device for the measurement of spectral transmittance, spectral reflectance, or relative spectral emittance.

Spatial arrangement of components of radiant energy in order of their wavelengths, wave number or frequency.

Specular Gloss
Relative luminous fractional light reflectance from a surface in the mirror or specular direction. Expressed as a ratio of incident to reflected light.

A heat treating process used to change all of the carbides in steel to rounded particles, or spheroids. A completely spheroidized structure is the softest and most workable structure for any composition.

Spinning Blank
A circular disk made from sheet or plate metal.

Spot Face
Circular flat surface as a bearing area for hardware.

Spring Back
Partial rebounding of formed material caused by its elasticity.

Spring Loaded Panel Fasteners
Inserted fastener which is equipped with a floating captive screw, spring and retainer such that the hardware will remain in the panel, ready for use, when the panel has been disassembled from its mating component.

Measure of perpendicularity of adjacent edges or surfaces.

Tolerance accumulations.

Stainless Steel
Various terrific alloys exhibiting high oxidation resistance through the alloying with chromium and nickel.

Discoloration on the surface of sheet metal, caused during mill processing.

Method of fastening using displaced material for retention.

Standard Vee Die
See “V Die.”

Stiffening Rib
Embossed feature in a sheet metal workpiece which is added to make the part more rigid.

Stock Check
A device used to grip the material as the feed retracts, preventing movement of the material during the forming cycle.

Stock Reel
A powered or non-powered device used to support a coil of material as it is fed into the machine.

Stock Straightener
A machine mounted device consisting of a series of adjustable rolls used to straighten wire or strip stock as it comes off the coil.

Stretcher Leveled
A flattening process in which a material is stretched to achieve a desired flatness tolerance.

Strip Edge Forming
The use of a rolling technique to edge roll slit strip with shaped edge rolls to provide an edge finish equal to the material’s surface finish. Also called edge conditioning.

Mechanical hold-down device applied to the workpiece during the punching process.

Stripper Marks
Imprints on one side of the stock around pierced holes, caused by punch strippers.

Process of disengaging tooling from the workpiece.

Sheet material, sheared into narrow long pieces.

RAM travel from top dead center (TDC) to bottom dead center (BDC).

Original material surface to which a coating is applied.

The ability of the CAD software to recognize that a closed geometric shape represents a surface of a part. Includes recognition of wireframes.

Surface Inclusions
Debris rolled into the skin of material causing a depression or thinly coated pocket.

Surgical Stainless Steel Types
Any of the 300 series stainless steels with an 18% chromium and 8% nickel content. Also includes the PH type of stainless steels.


Total indicator reading. Absolute sum of all dimensional variance.

Tack Weld
Usually refers to a temporary weld used to hold parts in place while more extensive, final welds are made. In some sheet metal applications, tack welds may provide sufficient strength to eliminate the need for an “all around” fillet weld.

Tap Drill Size
See “Core Hole.”

A flexible plastic wound strip coated with magnetic oxide and used for storing electronic data.

Tape Adhesion Test
Adherence test for painted surfaces conducted by cross hatching the surface with a sharp knife in a 1/8 inch grid pattern, applying tape (usually 3M Scotch k600 or H250), allowing to sit for a specified period, and then removing with a quick pull perpendicular to the surface of the part. Adherence is measured by the percentage of paint remaining within the grid.

Operation to create internal threads by either cutting or forming.

Temper Designation
Identifying systems to denote the hardness of a particular material.

Reheating quenched steel to a temperature below the critical range, followed by any desired rate of cooling. Tempering is done to relieve quenching stresses, or to develop desired strength characteristics.

Tensile Strength
Breaking strength of a material when subjected to a stretching force.

Test File
A CAD system file used to test the compatibility of supplier and customer CAD systems.

Text Files
A file containing words, but no pictures.

Structure of a surface as it affects appearance or feel.

Gauge or depth of material.

Thread Rolling Tap
Tool to generate internal threads by displacing and flowing metal into a thread shape.

See “Micro Ties.”

TIG Weld (Tungsten Inert Gas)
Process using a nonconsumable tungsten electrode and a shielding gas; filler material optional.

Permissible variation from a specification for any characteristic of the product.

Tool (mandrel, chuck)
The “mold” from which the part is made.

Tooling Holes
Openings provided in parts for location purposes during production.

Turning force.

Exchanging electronic data from one medium to another.

Transfer Die
Variation of a progressive die where the part is transferred from station to station by a mechanical system. Mainly used where the part has to be free from the strip to allow operations to be performed in a free state.

Transfer Mechanism
Apparatus used to move a part between die stations.

Transfer Protocol
The mutually agreed upon setting used by two computers in data transmission.

Tungsten Electrode
Current carrier made from the metal tungsten for its high heat resistance.

Rotary tool holding device in CNC punch presses.

Turret Press
Automatic punch press indexing the material and selecting the intended tool out of the rotary tool holding device (turret) totally by computer control for piercing, blanking and forming workpieces as programmed.

The rotation of two opposing edges of material in opposite directions.


Sound vibration above the audible range.

Condition of the stock resulting from welding or grinding below a desired plane.

The act of developing a fiat pattern.

A computer operating system. The more complex CAD systems require UNIX.


V Die
Tool used in conjunction with a V punch.

V Punch
Vee shaped tool used for angle forming.

Vibratory Finishing
Burr removal process in which an appropriate number of parts, depending on part size and abrasive material, is accelerated and decelerated by mechanical means inside of a drum-like enclosure.

Viewing Angle
Inclination from which a surface is observed, i.e. looking straight at the object 90°.

Viewing Time and Distance
Specified period to inspect a surface condition at a preset dimension from the eye.

Internal friction within a fluid which makes it resistant to flow.

Area in a weld in which insufficient filler material is deposited.


Generic designation for a variety of organic finishes which indicates that they are compounded with water as a dilutant rather than a volatile organic solvent.

Substance which dissolves in water.

Watts per square inch
Measure of speed based on power level of laser cutting machine.

(1) Material between two openings or edges. (2) See “Micro Ties.” (3) In some industries, thin material to be punched.

Weld Accessibility
Ease of reaching the weld area with the torch or electrode.

Weld Distortion
Depression or bulge on surface, caused by thermal expansion.

Weld Nut
Internally threaded hardware designed to be spot or projection welded onto sheet metal parts.

Weld Stud
Externally threaded hardware in various lengths in headed and head-less version, welded in place.

Ability of a material to be fused successfully without special processing.

Weld-To-Edge Distance
Minimum distance from a spot weld to the material edge to create an acceptable spot weld.

Weld-to-Form Distance
Minimum distance from a formed area to electrodes to avoid shorting.

Weld-to-Weld Spacing
Minimum distance between spot welds to avoid shunting through the existing weld spot.

Wet Film Thickness
Thickness of the liquid coating film immediately after application.

Wet-Film Gauge
Device for measuring the film thickness of coatings prior to drying or curing.

Wipe Die
Forming tool using two opposing edges, separated by one material thickness, moving past each other to form material.

Wire Form
A formed metal part made from wire that is usually fabricated on a slide forming machine.

Wire Line
A standard dimension from the bed of the slide forming machine to the material. Used in tool layout.

The capability of the CAD software to represent a design as a three dimensional arrangement of lines and arcs.

Work Hardening
Increase in tensile strength of material resulting from cold working process.

Work Hole
See “Tooling Hole.”

Mechanical device which holds a workpiece

Workholder Mark
Marring of material through the use of clamping device.

Condition in a paint film appearing as ripples: (1) produced intentionally as a decorative effect or (2) Defect caused by drying conditions or an excessively thick film.

Describes material which has been plastically deformed into shape as by mill rolling. Attached to that entry also are the terms Yield Strength and YMODEM and their definitions. Yield Strength should be called out separately on the “Y” page and will read: Maximum stress that can be applied without permanent deformation of material. YMODEM should also be called out separately on the “Y” page and will read: A protocol for transferring drawings as electronic files.




Zinc Plating
See “Electroplating.”

A protocol for transferring drawings as electronic files.

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