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Metal Forming Glossary
To help site visitors better understand metal forming, and other related metal fabricating processes, Precision Metalform has compiled this glossary of metal forming and associated industry terms.
A
Abrasion resistance
The ability of any material to withstand rubbing, scraping and other eroding forces.
Abrasive Media
Material or process used to carry particles for the purpose of material removal.
Actual weight
Actual weight is also called the scale weight. Material is bought by the actual (scale) weight of the product. The theoretical weight is used in estimating only.
AISI
American Iron and Steel Institute. AISI serves as the voice of the North American steel industry in the public policy arena and advances the case for steel in the marketplace as the preferred material of choice. AISI also plays a lead role in the development and application of new steels and steelmaking technology.
Alloy
A substance that has metallic properties and is composed of two or more chemical elements of which at least one is an elemental metal. This mixing is generally done to increase strength or give the base metal important properties.
Alodining
The trade name for the process of applying a chromate conversion coating on aluminum.
Aluminum
Aluminum is a silver-white metallic element, light in weight, malleable, ductile, and not readily corroded or tarnished. It is the third most common element, and is denoted by the symbol (Al). It has an atomic number of 13, an atomic weight of 26.9815, a melting point of 650°C, and a boiling point of 2450°C. It is also highly conductive, and resistant to wear. The most common uses for aluminum are beverage cans, aircraft and automobile parts, and electrical equipment.
Aluminum alloy
Pure aluminum that has been melted together with other ingredients to achieve specific physical and mechanical properties.
Aluminum oxide
A hard mineral comprised of aluminum and oxygen (AlO3), commonly used in abrasive products.
Annealed, fully
The heat treating process, by which metal is heated to a temperature above its critical range, held at that temperature until full recrystallization is achieved, then slowly cooled through its critical range. Final product is free from all work strains, and is at its maximum ductility.
Annealing
A process involving the heating and controlled cooling of materials, generally metals, for the purpose of reducing stresses, to induce softening, changing ductility, electrical properties and others. The term refers to treatments intended to alter mechanical or physical properties or to produce a definite microstructure.
Anode
A positively charged electrode.
Anodizing
The process of applying a controlled oxide layer to the surface of aluminum.
Arcs
Partial circles used to describe rounded corners of material and show bends in material.
Artificially Aged
Hardening process of material accelerated by temperature.
Aspect ratio
The maximum length-to-thickness ratio of which a process is capable.
ASME
American Society of Mechanical Engineers. Founded in 1880 as the American Society of Mechanical Engineers, is a professional organization focused on technical, educational and research issues of the engineering and technology community. ASME conducts technical publishing operations, holds technical conferences worldwide, and offers professional development courses. ASME sets internationally recognized industrial and manufacturing codes and standards that enhance public safety.
ASTM
American Standard of Testing and Materials. A non-profit organization that provides a forum for producers, users, ultimate consumers, and those having a general interest (representatives of government and academia) to meet on common ground and write standards for materials, products, systems, and services. Those standards are a series of documents, approved and published by ASTM, that include specifications or requirements, practices, guides, test methods, etc., covering various materials, products, systems or services. In the steel industry, the steel related ASTM standards are used by both the producers and users to ensure that a steel product or service meets all intended requirements. See ASTM - American Society for Testing and Materials.
AutoCAD
A brand name of CAD software prevalent in the computer aided design industry.
B
Back gage also back gauge, or back stop
Stop located in the rear of a metal forming or fabricating machine which is used to position the workpiece during an operation.
Banding
Strong, lightweight ribbons, generally of steel or nylon, applied under tension to strap packages on a pallet. Same as strapping.
Bar coding
Machine readable alphanumeric information used for identification of stations, processes, parts, or material.
Bare spot
A location on material where coating did not hold.
Barrel tumbling
Process in which parts to be deburred are put together with abrasive material into a drum, enclosed and slowly rotated for prolonged periods for the purpose of burr removal.
Bead
1) The term referring to material laid by a single welding pass.
2) A narrow ridge in a sheet metal workpiece or part, commonly formed for reinforcement.
Bed
Bottom transverse structural member on a metal forming machine.
Belt sanding
Material removing process in which an abrasive impregnated endless cloth belt uniformly and directionally sands material.
Bend angle
The angle through which a bending operation is performed, that is, the supplementary angle to that formed by the two bend tangent lines or planes.
Bend radius
The inside radius of a bent section or a formed feature.
Bend relief
The clearance notch at an end of a flange, allowing bending without distortion or tearing of the adjacent material.
Bendability
Indicated by the minimum bending radius attainable by a given material.
Bending
A term typically applied to a metal forming process. It is the creation of a formed feature by angular displacement of a sheet metal workpiece. The straining of material, usually flat sheet, by moving it around a straight axis lying in the neutral plane. Metal flow takes place within the plastic range of the metal, so that the bent part retains a permanent form after removal of the applied stress. The cross section of the bend inward from the neutral plane is in compression; the rest of the bend is in tension.
Bending brake or brake press
A single-action press that is comparatively wide between the housings, with a bed designed for holding long, narrow forming edges or dies. Used for bending and forming strip, plate, and sheet.
Bending dies
Dies used in presses for bending sheet metal into various shapes. The work is done by the punch pushing the stock into voids or depressions of similar shapes in the die.
Bending stress
A stress involving tensile and compressive forces, which are not uniformly distributed. Its maximum value depends on the amount of flexure that a given application can accommodate. Resistance to bending can be termed stiffness.
Bi-planar
Referring to surfaces that meet at an angle in different planes.
Black-oxide finish
Black oxide refers to a hot process using generic mixtures of caustic soda, sodium nitrite / nitrate, wetting agents and stabilizers or from proprietary mixes to produce an attractive but very thin and marginally corrosion-resistant, dark black iron oxide finish.
Black plate
Any steel that has not been coated also referred to as hot rolled.
Blank
In forming, a piece of sheet metal stock from which a product is made. Material, produced in cutting dies, that is usually subjected to further forming operations.
Blanking
The operation of punching, cutting, or shearing a piece out of stock to a predetermined shape.
Bleeding
A coating defect consisting of the movement of an ingredient to the surface of an applied coating to the base material: The outward creep of the applied process material generally in the silkscreening, or printing process, onto an adjoining area. The term "blooming" is also a form of bleeding, but it is normally used when describing lubricants rather than pigments.
Bleed-out
Leaching of entrapped plating solutions, causing surface discoloration and corrosion.
Blind fastener
Fastener which is capable of being permanently installed and used in a workpiece or assembly 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.
Blocking
Another coating defect consisting of the adhesion of two adjoining coatings or materials. Usually this term refers to the coating on one side of coated plate being tacky or sticky and adhering to the adjacent sheet.
Bottoming
Forming operation in which the punch and the die are closed completely on the workpiece.
Bottom bending
Press-brake bending process in which the upper die (punch) enters the lower die and coins or sets the material to reduce spring back.
Bow
Gradual deviation from straightness of the edge of sheet or coil stock.
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.
Brake press
A single-action press that is comparatively wide between the housings, with a bed designed for holding long, narrow forming edges or dies. Used for bending and forming strip, plate, and sheet.
Brass
An alloy of copper and zinc.
Breakage
The space, per side, between the punch and die on a trim or pierce die. Also called clearance or die clearance.
Brittleness
A tendency to fracture without significant deformation.
Brushing or Etching
Mechanical or chemical cleaning of parts before further processing.
Buckling
A deformation pattern perpendicular to the surface of a sheet caused by compressive stresses. Buckling in the flange of the part is referred to as wrinkling, and buckling in the wall of the part is referred to as puckering. A buckle is generally a bulge, bend, kink, or any other wavy condition of the workpiece caused by compressive stresses.
Buffing
To polish using a soft cloth or other similar applicator by applying polishing compounds or jewelers rouge.
Burn mark
Heat discoloration created in the contact area of a welding electrode.
Burr
A thin ridge, raised sharp edge, or roughness left on sheet metal blanks by cutting operations such as shearing, punching, blanking, or sawing.
Burr height
Height to which burr is raised beyond the surface of the material.
Burr rollover
Condition of burr displacement resulting from mechanical deburring operation.
Burr-free
Edge without sharp protrusions.
Burring
A common term for deburring or smoothing the rough cut edges of metal.
Buss bar
Bar, generally of copper with minor alloying constituents and high conductivity used for electrical applications.
Butt
The end of a bar, or "end to" orientation of a bar to another piece of material (to butt up against).
C
CAD
Acronym for Computer Aided Design.
CAM
Acronym for Computer Aided Manufacturing.
Camber
The gradual deviation from straightness of the edge of sheet or coil stock caused during the slitting operation.
Camber tolerances
Camber is the deviation from edge straightness. ASTM Standards define the maximum allowable tolerance of this deviation of a side edge from a straight line.
Canning
A dished distortion in a flat or nearly flat sheet metal surface, also referred to as oil canning.
CAR
Corrective action request.
Carbon steel
A steel that owes its specific properties chiefly to the presence of carbon, without substantial amounts of other alloying elements. It is also referred to as black steel, straight carbon steel, or plain carbon steel.
Cathode
Negatively charged electrode.
Center
The point that is defined midway between the extents (of a hole) in both the X and Y directions.
Chamfer
A beveled surface to eliminate an otherwise sharp corner that is typically about a 45° angle. A relieved angular cutting edge at a tooth corner.
Checking
Surface ripples and cracks induced by forming.
Chemical Etching
The process of removing material-etching, through the use of chemical activity
Chemistries (MTR - Mill test reports)
The documentation of the chemical composition of material denoting the amount of carbon, manganese, phosphorous, sulfur, lead etc.
Chromate
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 clear, or a variety of colours, as an esthetic enhancement.
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.
Chute
A trough in which blanks, workpieces, scrap, or parts are fed to or conveyed away from a die or press.
Circle
A perfect continuous arc, starting and ending at the same point.
Class 1 surface quality steel
A class of cold rolled steel processed to meet requirements for controlled surface texture, flatness, and temper requirements. This steel is commonly produced for use in exposed applications.
Clearance
1) The space, per side, between the punch and die. This space is also called breakage on trim and/or pierce dies. Clearance changes depending on material thickness.
2) The space between any two details.
Closed hem
A flange that is folded back over upon itself. It is used primarily for appearance and removal of dangerous sheared edges.
CNC
Acronym for Computer Numerical Control.
CNC machine centre punch press
Automatic punch press selecting the intended tool from a linear tool holder attached to the punch bed. Capable of higher tool holding capacity (up to 190 tools simultaneously), and faster tool changes than conventional turret presses. Computer controlled for increased efficiency and repeatability of punching operations (piercing, blanking and forming).
CNC turret punch press
Automatic punch press indexing the material and selecting the intended tool out of the rotary tool holding device (turret) by computer control for piercing, blanking and forming workpieces as programmed.
Coat
The paint, varnish or lacquer applied to a surface in a single application (one layer) forming a properly distributed film when dry.
Coating
The process of appling a coat to a surface.
Co-engineering
Process in which the customer and the supplier review and modify a design to simplify manufacturability of a part. See also "Manufacturing Review"
Coil
A length of steel wound into roll-form.
Coils
Coiled flat sheet or strip metal that is usually in one continuous piece or length.
Cold forming
See cold working.
Cold rolled
A metal finishing process that subjects strip or sheet steel to a cold-reduction mill. Steel that has been subjected to the cold rolling process is considerably stronger than hot-rolled sheet. See cold rolled sheet and cold rolled steel.
Cold rolled sheet
A mill product produced from a hot-rolled pickled coil that has been given substantial cold reduction at room temperature. The usual end product is characterized by improved surface, greater uniformity in thickness, and improved mechanical properties as compared with hot-rolled sheet. A product manufactured from hot rolled descaled (pickled) coils by cold reducing to the desired thickness, generally followed by annealing and temper rolling. If the sheet is not annealed after cold reduction it is known as full hard.
Cold rolled steel
Steel that was reduced to final thickness in the cold state by a rolling mill that creates a smooth surface with slight skin hardness.
Cold rolling
Rolling metal at a temperature below the softening point of the metal to create strain hardening (work-hardening). Same as cold reduction, except that the working method is limited to rolling. Cold rolling changes the mechanical properties of strip and produces certain useful combinations of hardness, strength, stiffness, ductility and other characteristics known as tempers. Term applied to the operation of passing unheated metal through rolls for the purpose of reducing its gauge.
Cold strain hardening
An increase in hardness and strength caused by plastic deformation at temperatures below the recrystallization range. Also known as strain hardening or work hardening.
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
The plastic deformation of metal under conditions of temperature and strain rate that induce strain hardening. Usually, but not necessarily, conducted at room temperature. Also referred to as cold forming or cold forging. Contrast with hot working.
Colour Chips
Paint samples.
Combined drill and countersink
Same as center drill.
Commercial tolerance
The range of difference that a product's specifications can deviate from the ordered specifications and still meet the industry accepted ranges as defined by ASTM Standards.
Commercial grade
Standard materials commonly available through supply houses.
Commercial drawing quality (CDQ)
Commercial drawing quality steel is a more flexible grade of steel. Flat-rolled products produced from either deep drawing rimmed steel or extra deep drawing aluminum killed steels. Special rolling and processing operations aid in producing a product that can withstand extreme pressing, drawing or forming, without creating defects.
Compressive strength
The maximum compressive stress a material is capable of withstanding without developing a predefined amount of deformation. With a brittle material that fails in compression by fracturing, the compressive strength has a definite value. In the case of ductile, malleable, or semi-viscous materials which do not fail in compression by a shattering or fracture, the value obtained for compressive strength is an arbitrary value dependent on the degree of distortion that is regarded as effective failure of the material.
Compressive stress
A stress that causes an elastic body to deform (shorten) in the direction of the applied load. Opposite of tensile stress.
Concealed Head Fastener
A fastener installed in a blind hole.
Concentricity
Dimensional relationship of 2 or more items sharing a common center line.
Conditional match
Perceived identity of colour exhibited by a pair of colours, each with different spectral distribution curves. Also called Metameric match.
Conductive Paint
Organic coating that conducts electrical current.
Conductivity
Ability of a material to conduct electricity or heat.
Continuous weld
Continuously welding one coil to another at the entry end and splitting off coils of a specific weight at delivery end.
Conversion Coating
Treatment, either chemical or electrochemical, of the metal surface to convert it to another chemical form which provides an insulating barrier of exceedingly low solubility between the metal and environment, but which is an integral part of the metallic substrate. It provides greater corrosion resistance to the metal and increased adhesion of coatings applied to the metal.
Corner
Three surfaces meeting at one point.
Corner radius
Outside radius.
Corrosion Resistance
The ability of a substance to resist deterioration due to a reaction with its environment.
Corrugated
Metal that has been formed using the corrugating process. As a defect, material with alternate ridges and furrows or a series of deep short waves.
Counterbore
A rotary, pilot guided, end-cutting tool, having one or more cutting lips and usually having straight or helical flutes.
Counterboring
Enlarging a hole to a limited depth producing a flat bottom in the enlargement. A machining or coining operation to generate a cylindrical flat-bottomed hole.
Countersink
A funnel shaped enlargement at the outer end of a drilled hole having an 82° included angle to allow the head of a screw to be flush with or below the surface. Also, a bit or drill for making a countersunk hole.
Countersinking
Machining or coining operation to generate a conical angle on a hole.
Cratering
A coating defect consisting of small, apparently uncoated, spots of coated plate consisting of a very thin film of coating that has been contaminated by oil, silicone, or other foreign matter. Similar to "fish eyes" and "eye holing", but with metal exposure in the crater.
Creep
A term used in a hemming operation for the amount the part reduces in size along the flange radius when forming from a 90° flange to a full fold or hem.
Crimping
The forming of relatively small corrugations in order to set down and lock a seam, to create an arc in a strip of metal, or to reduce an existing arc or diameter. See also corrugating.
Crop
Material left after the shearing and blanking process is complete. Unusable crop is also referred to as scrap.
Cross-section
Sectional view of a part or material.
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. A shape (crown) ground into a flat roll to ensure flatness of cold rolled sheet (and hot) and strip.
Curling
The act of forming an edge of circular cross section along a sheet, or workpiece
Cut
To separate any portion of a workpiece from any other portion of the same workpiece by a step of machining (e.g., grinding, drilling, boring, milling, planing), severing (e.g., breaking, sawing, slicing, shearing), or by intrusion of a sharp-edged or pointed tool without removal of material (e.g., stabbing, splitting, intrusive punching).
Cut edge
The normal edge that results from the shearing, punching, or sawing process.
D
Date of manufacture
A date, either mechanically punched, or permanently ink stamped on a finished or semi-finished part.
Datum's
Theoretically exact planes, lines or points from which other features are located on design drawings.
Deburr
To remove the sharp, knife-like edge from parts.
Dedicated tooling
Commonly referred to as hard tooling. This is tooling made to produce a specific part.
Deep drawing
The fabrication process of flat rolled steel to make drawn parts. The part is mechanically formed through or in a die. The blank diameter is reduced; the blank contracts circumferentially as it is drawn radially inward. Deep drawing is 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. Deep drawing is also called cup drawing or radial draw forming.
Defect
Anything that renders the steel unfit for the specific use for its intended use such as punchmarks, roll marks, oil spots, and scratches. However, what is defective for one user may be prime steel for another.
Deflection
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.
Die
Tool with a void or cavity that is precisely fitted to a punch used to form material on a punch or brake press.
Die angle
Forming term used to denote the inside angle of a matched punch and die set.
Die assembly
The parts of a die stamp or press that hold the die and locate it for the punches.
Die block
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.
Die clearance
Amount of space between the punch and die opening.
Die impression
The portion of the die surface that shapes a sheet metal part.
Die life
The productive life of a die impression, usually expressed as the number of units produced before the impression has worn beyond permitted tolerances.
Die line
A line or scratch resulting from the use of a roughened tool or the drag of a foreign particle between tool and product.
Die lubricant
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.
Die marks
Scratches, scrub marks, indentations, galling or burnishing of sheet metal workpieces by tooling. (can be virtually eliminated in pressing with the use of urethane die blocks)
Die match
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 or forming tolerances.
Die post
Lower section of die on which the part nests. Also called an adapter, boss, horn, locator, master, master plug, and stool. Guide post where wear plates are attached.
Die shoes
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.
Dimension
A measurement describing size and/or appearance of a part feature.
Dimensional tolerance
A range by which a product's width and gauge can deviate from those ordered and still meet the order's requirements. Also see commercial tolerance.
Dimpling
The stretching of a relatively small, shallow indentation into sheet metal. In aircraft/aerospace industries, the stretching of metal into a conical flange for a countersunk head rivet.
Discoloration
l) Staining.
2) Changing or darkening in colour from the standard or original.
Distortion
Any deviation from a desired contour or shape.
Dowel
A round pin, usually case hardened, that fits into a corresponding hole to align two mating parts.
Draft
The taper given to a die so as to allow the part to fall through the die or be removed.
Drawing
1) A drawing or document that illustrates a part, component, or assembly
2) A term used for a variety of forming operations, in metal forming. The stretching or compressing of a sheet metal part into a die by a punch to create a 3-dimensional part. The process of cold forming a flat pre-cut metal blank into a hollow vessel without excessive wrinkling, thinning, or fracturing.
Drawn
A process where material is mechanically formed by tension through or in a die.
Drawn sheet
Sheet metal that has been mechanically formed by use of tension though a die or in a die.
Dry Film Thickness
Thickness of an applied coating after drying or curing.
Ductility
A property of material that indicates the extent or ability of it to be deformed without fracture in normal metal working operations.
E
Eccentric
The offset portion of the driveshaft that governs the stroke or distance the crosshead moves on a mechanical or manual shear.
Edge
A transition between surfaces.
Edge bulge
Condition resulting from any forming, piercing, hardware insertion or spot welding operation too close to an edge.
Ejecting
The removal of a part from a die by an air blast or mechanical means.
Ejector
A mechanism for removing a part from a die. Also called kicker or knockout.
Ejector plate
A plate used to push out a formed piece.
Elastic deformation
Stretching of the material below the point at which a permanent set takes place. That is, in the range where the metal acts spring-like or elastic.
Elastic instabilities
A section of a part that has two equilibrium positions and can be manually switched between each position. Elastic instabilities are created when a highly deformed area is constrained on all sides by regions of less deformed areas. Elastic instabilities are also referred to as oil canning.
Elastic limit
The maximum stress a material can sustain without any permanent strain (deformation) remaining upon complete release of the stress. See also
proportional limit.
Elasticity
The property of a material by which the deformation caused by stress disappears upon removal of the stress. A perfectly elastic body completely recovers its original shape and dimensions after the release of stress.
Electrode
In welding, a tungsten rod (TIG), consumable metal wire (MIG), or stick (ARC) which is used as an electrical conductor and arc point between the welding torch and the workpiece. 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.
Electrolytic galvanized
Cold rolled or black plate to which a coating of zinc is applied by electro-deposition and typically used for applications in which corrosion resistance and paintability is a primary concern.
Electrolytically deposited
Depositing of one material on another, generally referred to 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.
Emboss
A relatively shallow indentation or raised design with basically no change in metal thickness.
Embossing
A process for producing raised or sunken designs or relief in sheet material by means of male and female dies, theoretically with no change in metal thickness or by passing sheet or a strip of metal by passing between rolls of desired pattern. (See patterned or embossed sheet). Examples are letters, ornamental pictures, and ribs for stiffening.
Heavy embossing and coining are similar operations.
Embossing die
A die used for producing embossed designs.
Entity
A predefined element that is placed 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.
Etching
Printing technique in which a metal plate is first covered with an acid-resistant material, then worked with an etching needle to create an intaglio image. The exposed metal is eaten away in an acid bath, creating depressed lines that are later inked for printing.
Expanded metal
Sheets of metal formed from the stretching of uniformly parallel, staggered slits in sheet metal. Product is sieve like in appearance and can be flattened (requiring an additional process) or left raised (as manufactured).
Extruded hole
Pierced and formed hole in sheet metal in which the metal has been stretched creating a tubular shape.
Extruding
The turning up or drawing out of a flange around a hole which has been punched in a previous operation. Also called hole flanging. The punching and flanging of a hole in one operation generating a slug. The cutting or tearing (piercing) and flanging of a hole in one operation without generating a slug.Also called spearing or spear punching.
Extrusion
A metal forming process which a punch compresses a billet (hot or cold) confined in a container so that the billet material flows through a die in the same direction as the punch.
Eye holing
A coating defect, similar to cratering, but with exposed metal in the void.
Eyeleting
The displacing of material about an opening in sheet or plate so that a lip protruding above the surface is formed.
F
Fabrication
The use of techniques such as welding, bonding, bending, cutting, shearing and others to create parts or components, from parent materials. Generally used as a term in the metal or plastic forming industries.
Feather edge
Material thinning toward an edge, creating an irregular knife edge, "feathered" appearance. This is done for coating control on edge.
Ferritic
Referring to material containing iron.
Ferro magnetic
Various alloys that exhibit magnetic qualities.
Ferrous
Metals containing iron as a major alloying constituent.
Fillet
The concave intersection of two surfaces.
Fillet weld
Joining method of filling an inside edge with welding metal.
Finish
The surface appearance or texture of a product, achieved either in production or through the addition of a post production process.
Finish form
The act of forming a panel shape to the finish position. Also see restrike.
Fish eyes
A coating defect consisting of undissolved particles in the coating usually surrounded by a circular crater. The particles are usually resinous and are raised up from the cured surface with the appearance of the eye of a fish.
Fit
Extent of physical match between two or more parts or components.
Fixture
Tooling designed to locate and hold components in position.
Flange
A projecting rim or edge of a part, usually narrow and of approximately constant width for stiffening or fastening.
Flange die
Die used to form a flange from a blank.
Flange relief
Flange material that has been cut to allow flange to lay flat after final hem.
Flange steel
A steel used in a forming operation in which a narrow strip at the edge of a sheet or part is bent down along a straight or curved line. Also called a wiping steel.
Flanging
A variable that is intentionally changed in a controlled manner during an experiment to observe its effects on the response variable, sometimes called an independent variable or causal variable.
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 rolled steel
Steel produced on rolling mills utilizing relatively smooth, cylindrical rolls. The width to thickness ratio of flat rolled products is usually fairly large. Examples of flat rolled steel products are hot-rolled, cold-rolled, and coated sheets and coils, plus tin mill products.
Flat surface
Contour with no radius.
Flatness
The absence of any gap or clearance when a strip is placed, without applying any pressure, between two parallel-faced plates.
Flattened hem
A flange that is folded back over upon itself. It is used primarily for appearance and removal of dangerous sheared edges. Also called closed hem.
Flattening dies
Dies used to flatten sheet metal hems; that is, dies that can flatten a bend by closing it. These dies consist of a top and bottom die with a flat surface that can close one section (flange) to another (hem, seam).
Floating fastener
Hardware which allows the threaded portion to move within its particular confines without rotating, to compensate for misalignment.
Flow lines
Texture showing the direction of metal flow during hot or cold working. Flow lines can often be revealed by etching the surface or a section of a metal part.
Foil
Metal in sheet form that is less than 0.15 mm (0.006 in.) thick.
Folds
Defects caused in metal by continued fabrication of overlapping surfaces.
Form
A bend, or the process of bending a metal formed part.
Form die
A die used to change the shape of a sheet metal blank with minimal plastic flow.
Formability
The ease with which a metal can be shaped through plastic deformation. Evaluation of the formability of a metal involves measurement of strength, ductility, and the amount of deformation required to cause fracture. The term workability is used interchangeably with formability; however, formability refers to the shaping of sheet metal, while workability refers to shaping materials by bulk forming.
Formed
A material, metal for this purpose, that has undergone plastic deformation between tools (dies) to obtain the final configuration.
Formed tab
Small flange bent at an angle from the body of a metal workpiece.
Forming
The plastic deformation of a billet or a blanked sheet between tools (dies) to obtain the final configuration. Metalforming processes are typically classified as bulk forming and sheet forming. Also referred to as metalworking. Making any change in the shape of a metal piece which does not intentionally reduce the metal thickness and which produces a useful shape.
Fracture
The surface appearance of metals when they are broken.
Friction gouges or scratches
A series of relatively short surface scratches variable in form and severity.
Functionality
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. It is used to generate little, if any, eruption above the original surface level.
G
Gage also gauge
1) The thickness of sheet or the diameter of wire. The various standards are arbitrary and differ with regard to ferrous and non-ferrous products as well as sheet and wire.
2) An aid for visual inspection that enables an inspector to determine more reliably that the size or contour of a formed part meets dimensional requirements.
3 ) A device used to position work in a die accurately.
Galling
The damaging of one or both metallic surfaces by removal of particles from localized areas due to seizure, during sliding friction.
Galvanizing
Free zinc coatings applied to a hot rolled or cold rolled steel to produce Galvanized steel. Application may by either hot-dip or electrolysis.
Galvannealing
An extra light coat of galvanizing metal (zinc) applied to a carbon steel sheet, after which the sheet is passed through an oven at about 1200°F. The resulting coat is dull gray without spangle that is especially suited for painting (also referred to as Satin Coat, Wipe Coat, or Light Coat sheet).
Gap-frame press
A general classification of press in which the uprights or housings are made in the form of a letter C, making three sides of the die space accessible.
Gas cylinder
A gas charged cylinder used in place of springs or die cushions in applications in which high initial pressure is required. Also called nitrogen die cylinder, nitro-dyne cylinder, and hyson cylinder.
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.
Gauge tolerance / gage tolerance
A range by which a product's gauge can deviate from the nominal size, and still meet the specified requirements.
Gouge
Surface imperfection, deeper than a scratch, often with raised edges.
Grain
Refers to grain fiber following the direction of rolling and parallel to edges of metal strip or metal sheets. In steel, the ductility in the direction of rolling is almost twice that at right angles to the direction of rolling.
Grain direction
Crystalline orientation of material in the direction of mill rolling or the orientation of a surface finish generated by an abrasive method.
Grain size
The average diameter of grains in the metal under consideration, or alternatively, the number of grains per unit area. Grain size is a significant issue since an increase in grain size is accompanied by lower ductility and impact resistance. The addition of certain metals to steel affects grain size. Vanadium and aluminum tend to give steel a fine grain when added. The ASTM has set up a grain size standard for steels.
Grinding
Process of removing material with abrasives.
Grippers
Material clamping devices often serrated for additional holding force to restrain material during a die operation.
Ground flat stock
Annealed and preground (to close tolerances) tool steel flats in standard sizes ready for tool room use. These are three common grades; water hardening, oil hardening and air hardening quality.
H
Haeger
Manufacturer of machines and tooling systems used to press in self-clinching fasteners into sheetmetal parts and components. Haeger machines are similar in basic function to an arbor press, though much more automated and precise.
Half shearing
A partial penetration piercing, creating a locating button with a height of about ½ material thickness.
Hard tooling
Tooling made for a specific part commonly referred to as dedicated tooling.
Hardened and tempered spring steel strip
A medium or high carbon quality steel strip which has been subjected to the sequence of heating, quenching and tempering.
Hardening
Any process which increases the hardness of a metal. Usually heating and quenching certain iron base alloys from a temperature either within or above the critical temperature range.
Hardness
The degree to which a metal will resist cutting, abrasion, penetration, bending and stretching. A measure of the "temper" of a material. Tensile strength is the indicator for the relative hardness of a material.
Hardware
Fasteners inserted into a sheet metal part.
Hardware list
See kitting.
Heat treatment
Heating and cooling a solid metal or alloy in such a way that desired structures, conditions or properties are attained. Heating for the sole purpose of hot working is excluded from the meaning of this term. Heat treatment usually markedly affects strength, hardness, ductility, malleability, and similar properties of both metals and their alloys.
Hem
Edge of material doubled over onto itself for the purpose of safe handling or to increase edge stiffness.
Hem steel
The steel in a hem die that finishes and flattens the hem. Also called hammer steel.
Hemming
A bend of 180° (made in two steps). First, a sharp-angle bend is made and then the bend is closed using a flat punch and a die.
Hemming die
A die which folds the edge of the part back over on itself. The edge may or may not be completely flattened to form a closed hem.
Hold down
An object used to secure a workpiece.
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 diameter
Units: mm (SI), inch (Imperial) The minimum hole diameter which can be created by the process. Casting, stamping and molding impose limits on minimum hole size which can be overcome by creating the holes with a secondary process such as drilling or laser cutting.
Hole flanging
The forming of an integral collar around the periphery of a previously formed hole in a sheet metal part. See extruding.
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.
Homing the die
Adjusting press ram/slide so die is on bottom or on the stop blocks at the bottom of the press stroke. Also called bottoming the die.
Homogenizing
An annealing treatment at a fairly high temperature designed to eliminate or reduce chemical segregation.
Hone
A fine grit stone used with a fluid for sharpening or smoothing a surface. Also see superior hone.
Horn
Lower section of the die on which the part nests. Horns are also called an adapter, boss, die post, locator, master, master plug, and stool. The portion of the die or part that protrudes.
Hot rolled sheets
Manufactured by hot rolling slabs to the required thickness. Steel which was rollerformed from a hot plastic state into final shape and is characterized by a rough, scaly surface.
Hydraulic press
A machine that exerts working pressure by hydraulic means.
Hydraulic press brake
A press brake in which the ram is actuated directly by hydraulic cylinders.
Hydraulic shear
A shear in which the crosshead is actuated by hydraulic cylinders.
Hydraulic-mechanical press brake
A mechanical press brake that uses hydraulic cylinders attached to mechanical linkages to power the ram through its working stroke.
Hydraulics
Hydraulics is the science pertaining to liquid pressure and flow. Hydraulics utilizes the transfer of energy in the form of a non compressible pressurized liquid, generally oil. The oil is kept in a reservoir and pushed within the circuit by a pump. Pressure exerted within the system by the pump is stored in the oil as potential energy. That potential is then used to operate machinery, through the use of high pressure cylinders, motors, hoses, valves and actuators.
I
Impact resistance
Ability of a material to resist deformation from an impact force.
Impression
A mark produced on a surface by pressure during common metal forming operations.
Inclusion(s)
Particle(s) 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.
Insert
A separate steel which is mounted upon or into another section to aid in ease of repair or to extend wearability. It may be of similar or dissimilar metal than parent metal.
Inserted fastener
A variety of pins, including nuts, studs, standoffs, panel fasteners, pilot pins, etc. or special hardware, which are installed in a workpiece by inserting it into a specifically punched hole.
Inside radius
The radius of a bend that is under compression. Normally defined as Ri.
Inspection criteria
Characteristics by which the part will be evaluated both dimensionally and cosmetically.
Inverted die
A die in which the conventional positions of the male and female members are reversed.
ISO drafting standards
Standards for the creation of technical drawings published by the International Standards Organization.
J
Jig
See fixture.
Joggle
An offset surface consisting of two adjacent, continuous, or nearly continuous short radius bends of opposite curvature.
Julian date
See "Ordinal date"
K
Kelly screws
A socket head cap screw with the head and the upper portion of the body turned down, leaving a minimum number of threads on the end of the body. Used where the screw hole in the detail does not align with the threaded hole in the mounting surface. Also called Chicago screws, Eberly screws, or rubber screws.
Key (external)
A block partially mounted in a pocket at the perimeter of a die member to locate, add support, and/or back up that die member. It is accessible without removing the die member.
Key (internal)
A block mounted in mating pockets between two die members to locate and/or add support to those die members. It is not accessible without removing the die members.
Kicker
A mechanism for removing a part from a die. Also called an ejector or knockout.
Kitting
The compilation of all necessary hardware for a specific part, work order, or job, into one container. All individual hardware types are maintained separately within that container.
Knockout
A mechanism for releasing workpieces from a die.
L
L.A.S.E.R.
Acronym for "Light Amplification by Stimulated Emission of Radiation".
Lanced and formed tab
See formed tab.
Lancing
Cutting along a line in the workpiece without producing a detached slug from the workpiece.
Lap-welded joint
Welded seam in which the two metal pieces to be joined overlap one another.
Laser cutting
A cutting process that severs material with the heat obtained by directing a laser against a metal surface. The process can be used with or without an externally supplied shielding gas.
Laser welding
Metal melting and fusing using the energy of a laser beam.
Lead time
Time required to manufacture a product from order placement until availability.
Leveling
The flattening of rolled sheet, strip, or plate by reducing or eliminating distortions. See stretcher leveling and roller leveling. The process whereby a coil of steel is flattened through several sets of opposing rollers which first overbend the blank and then progressively bend to true flatness.
Lifter
A mechanism for raising a part in a die to a height for advancing it to another station, as in a progressive die, or for ejecting it from the die. Also incorrectly called a kicker or ejector.
Liftout
The mechanism also known as knockout.
Limiting dome height
The greatest depth that a material can withstand under the pure stretching of a hemispherical punch. This is a standard measurement of stretchability.
Lines
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.
Louver
An opening with a series of slats so arranged as to permit ventilation, but minimize effects of rain, light, or vision.
Lubricant
Any substance interposed between two surfaces in relative motion for the purpose of reducing the friction and/or wear between them.
M
Machinability
The relative ease of machining a metal.
Machining
This is the group of processes in which a shape is generated by removing unwanted material. Machining can be used to make a component from stock material but more often it is used as a secondary process to impart a shape or a level of precision to a manufactured component that cannot be achieved otherwise. Shape restrictions exist for some machining processes.
Magnetic Thickness Gauge
Device, applicable only to ferrous substrates, which measures the thickness of non-conductive coatings
Malleability
The property that determines the ease of deforming a metal when the metal is subjected to rolling or hammering. The more malleable metals can be hammered or rolled into thin sheet more easily than others.
Manufacturability
The degree to which a product can be efficiently and accurately produced using modem manufacturing methods.
Manufacturing review
Precision Metalform conducts a manufacturing review to confirm aptitude to produce a part or product. The manufacturing review assesses all the technical requirements needed to produce consistent quality individual parts or assembled enclosures.
Map
A simplified detail print or sketch usually showing just the location and sizes of holes in a detail or steel.
Marriage gap
Space between the trim edge of the inner panel and the inside of metal of the outer panel flange before hemming.
Martensitic stainless steel
Select group of 400 or 500 Series stainless steels that are magnetic and are able to be hardened by heat treating.
Masking
Temporary shielding of a portion of a product to selectively prevent the application of a coating.
Master die
Universal tool receptacle for holding changeable tool systems.
Match
A condition in which a point in one die half is aligned properly with the corresponding point in the opposite die half within specified tolerance.
Material utilization
Extent to which optimal use of material is approached.
Mating flange area
Area of inner panel covered by flange of outer panel.
Mating surface
Area of inner panel that is in contact with outer panel.
Matte finish
A dull or grit surface appearance.
Maximum dimensions
The largest dimension of a component which can be created by a particular process. In most processes it is limited by the parent material capacity of the specific machine.
Measurement and inspection gauges
Precision-made mass production tooling used by workers to test and/or check mass produced components for conformance to engineering requirements and specifications, often to very high levels of dimensional and/or form accuracy.
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.
Mechanical properties
Properties of a material that reveal the elastic and inelastic reaction when force is applied, or that involve the relationship between stress and strain such as the modulus of elasticity, tensile strength, and fatigue limit. These properties are oftentimes referred to as "physical properties".
Metal
The material subjected to an operation of a forming class type. An elemental metal or alloy of metal mixture in a self-shape-sustaining state (this excludes molten, gaseous, or powdered).
Metal arc weld
Metal melting and fusing process using a continuous, consumable, metal electrode with an inert gas around the electrode to shield against oxidation.
Metal clearance
The running clearance on bottom of press stroke between flange steels or male and female form steels.
Metal forming
The process by which metal is worked either by shearing, punching, bending, spinning, drawing, etc., to create parts, blanks or components.
Metal thinning
The thickness reduction of material during any forming operation.
Metalworking
See forming.
Metameric match
See conditional match.
Micro ties
Thin bridges of metal which are left to hold parts in place during punch fabrication.
MIG Weld (Metal Inert Gas)
MIG stands for Metal Inert Gas welding and is often referred to as wire-feed welding. MIG welding is a commonly used high deposition rate welding process. During the welding process, wire is continuously fed from a spool with an inert gas around the electrode to shield against oxidation.
Mill
A factory in which metals are hot worked, cold worked, or melted and cast into standard shapes suitable for secondary fabrication into commercial products. A production line, usually of four or more stands, for hot or cold rolling metal into standard shapes such as bar, rod, plate, sheet, or strip. A single machine for hot rolling, cold rolling, or extruding metal.
Mill edge
The edge of strip, sheet or plate in the as-rolled state. It is unsheared.
Mill finish
A surface finish produced without being subjected to a special surface treatment (other than a corrosion-preventive treatment) after the final working or heat-treating step on sheet and plate.
Mill scale
The heavy oxide layer that forms during the hot fabrication or heat treatment of metals.
Minimum corner radius
The minimum radius of curvature at a corner that can be created by the process
Model
1) Pre-production sample made with limited emphasis on tolerance to test a design concept, also referred to as a prototype.
2) A computer graphic depicting exact geometry of a part.
Modified flat hem
Modified flat hem is believed to create better reflection characteristics on the finished panel assembly.
Modulus of elasticity
The number that represents the relative springiness of a given type of metal. All steels have the same modulus of elasticity or springiness regardless of the tensile or yield strengths. That is, until the yield point is reached they all stretch the same amount for a given load.
N
NC
Numerically controlled. See CNC.
NCMR
Non conforming material report.
Nest
To stack like parts within one another to occupy a minimum space. A plate having an opening to conform to the contour of a part used to locate the part in a die. To lay out a blank so that the outlines of parts produced will interlock with each following and each preceding part and require the minimum amount of material.
Nesting
Grouping of identical or different parts in multiples within a workpiece to conserve material. The process of accurately locating and holding the part in a die or fixture by using gages or the part's form.
Nibble marks
Slight irregularities at the edge of the stock surface after progressive punching ("nibbling") operations in a turret press.
Nominal
The targeted value for a dimension that defines the size of an ideal part.
Nominal strength
The maximum stress (tensile, compressive, or shear) a material can sustain without fracture; determined by dividing maximum load by the original cross-sectional area of the specimen. Also known as maximum strength or ultimate strength.
Non-ferrous metal
Elements and their alloys without iron as a major constituent.
Non-geometrical
Information other than that directly related to the shape of the product such as notes, part numbers, material lists, tolerances, and others.
Notching
A metalworking operation in which the punch removes material from the edge or corner of a strip or blank or part.
Nugget
Area melted together during resistance welding.
O
Obround
Contraction of the words oblong and round denoting a punched slot with semicircular ends and straight sides.
Oil canning
Out of flatness condition in sheet material also known as bow distortion 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.
Open hem
Also called as radius flat hem or loose hem. A flange that is folded back over upon itself with the edge of a mating part between the fold. This fastens the mating parts together.
Open surface
Rough surface on black plate, sheet or strip, resulting from imperfections in the original steel bars from which the plate was rolled.
Orange peel
Surface condition characterized by an irregular waviness of a paint finish, resembling an orange skin texture. A surface roughening (defect) encountered in forming products from metal stock that has a coarse grain size. It is due to uneven flow or to the appearance of the overly large grains usually the result of annealing at too high a temperature.
Orbital sanding
Non-straight-line abrasive finish with irregular circular marks.
Ordinal date
An Ordinal date is similar to a Julian date in the way it numerically represents dates and time. An ordinal date is specified with YYYY-DDD. Thus, April 5/1981 or 1981-04-05 is represented as 1981-095. The basic format of this drops the separator, becoming 1981095. Ordinal dates do not leave any implied variables in the ISO standard, as calendar dates do (which is what created the Y2K issue).
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.
Outside radius
The radius of a bend that is under tension. Normally defined as Ro
Overbending
Bending metal a greater amount than called for in the finished piece to allow for springback.
Overcrown
The term used to signify that the curvature of a surface is too high. Used for the overbending of a curved surface to compensate for spring back.
Overhaul
To overhaul a piece of equipment is to pull it apart, inspect it for damage, repair or replace damaged parts, then assemble the equipment and adjust so that it operates just as if it was new.
Overspray
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.
Oxidation
A common form of chemical reaction which is the combining of oxygen with various elements and compounds. The corrosion of metals is a form of oxidation, rust on iron for example is iron oxide.
Oxidation scale
Stained, discolored and/or flaky metal surface condition.
P
Parting
A specific kind of cutting operation in which complete severance of the stock strip is achieved by punching out a piece of stock material (scrap) from between the piece parts.
Passivating
Intended to improve the corrosion resistance of parts made from austentic, ferritic and martensitic corrosion-resistant steels of the 200, 300 and 400 series, and precipitation hardened corrosion-resistant steels. Passivation works by creating a protective oxide film on the surface of the stainless steel. This invisible film is extremely thin, less than 0.0000001 of an inch thick.
Pattern direction
Orientation of features or surface patterns on sheets and coils.
Patterned or embossed sheet
A sheet product on which a raised or indented pattern has been impressed on either one or both sides.
Pedestal
A block of steel or welded construction to which punch steels or punch retainers are mounted. Also called a punch rise or riser.
PEM fastener
Self-clinching inserted fastener (nut, stud, standoff, pin. blind stand off, etc.) made by Penn Engineering & Manufacturing Corp.
Penetration
1) depth of a cutting operation before breakout occurs.
2) In welding, the depth of material through which fusion occurs.
Perforating
The punching of many holes, usually identical and arranged in a regular pattern, in a sheet, workplace blank, or previously formed part. The holes are usually round, but may be any shape. The operation is also called multiple punching.
Perforator
A specific name for a punch that falls in the cutting punch category. See punch. Also called a pierce punch.
Periphery
The extreme outer edge of a part or drawing.
Permanent set
The deformation or strain remaining in a previously stressed body after release of the load.
Perpendicularity
Dimensional relationship of a part or datum located at right angles to a given feature.
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.
Pickling
Pickling restores the corrosion resistance to the same level as the basic material following welding. This is achieved by stripping the contaminated oxide layer via etching and allowing a new layer to form under controlled conditions.
Pickup
Small particles of oxidized metal adhering to the surface of a mill product.
Pierce
To cut, shear, or punch anopening in sheet metal, strip, plate or parts such as a slot or a hole.
Pierce block
An individual die part that contains one or more pierce holes or die buttons.
Pierce button
A small cylindrical die steel with an opening larger than the punch point size, generally by a percentage of the thickness of the material being pierced. It is also called a button or a die button.
Pierce punch
A specific name for a punch that falls in the cutting punch category. It is also referred to as a perforator.
Piercing
The general term for cutting (shearing or punching) openings, such as holes and slots, in sheet material, plate, or other material.
Piercing die
A die which cuts out a slug, which is usually scrap, in sheet or plate material.
Pilot
A pin or projection provided for locating work in a die from a previously punched hole. Also called locating pin or pilot pin.
Pinholes
A coating defect consisting of the randomly spaced small round holes (as a straight pin would make in the cured film) which quite often occur in large numbers. The open area (pinhole) usually exposes bare substrate. Contaminated substrate or improperly dispersed lubricant or additive may cause pinholes. Pinholes are typically caused by laminations, inclusions, scratches or gouges.
Pitting
A coating defect consisting of randomly spaced small depressions in the cured film. Pitting is similar to pinholing, except that pits do not expose the bare substrate.
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 anisotropy
This is the concept that a material has a preferred strain direction. In sheet material, plastic anisotropy is measured as the ratio of width strain to thickness strain. This value is called the r-value and measures the tendency of the sheet to thin under deformation. It also is an indicator of the directional differences in a rolled material like sheet.
Plastic deformation
Permanent deformation occurring in forming of metal after elastic limits have been exceeded under the action of applied stresses. The ability of metals to flow in a plastic manner without fracture is the fundamental basis for all metalforming processes.
Plastic flow
The phenomenon that takes place when metals or other substances are stretched or compressed permanently without rupture.
Plasticity
The property of a substance that permits it to undergo a permanent change in shape without rupture. See plastic deformation.
Plate
A flat-rolled metal product of some minimum thickness and width arbitrarily dependent on the type of metal. Sheet steel thicker than 7 gauge 0.179 in. (4.55 mm) or sheet aluminum thicker than 3/16 in./ .188 in. (4.76 mm).
Plating
A thin coating of metal applied on another material.
Pneumatics
If energy transfer is in the form of compressed airflow then it is known as pneumatics. In industry compressed air is generated by using a machine called a compressor, which draws in normal air, squeezes it to increase its pressure and then passes it through a moisture separator and stores it in the reservoir for later use in the factory.
Point
A piece of geometry at an exact location. Polishing Abrasive process in which the surface created takes on a bright reflective finish, scratch free to the unaided eye.
Point of origin
A point from which other dimensions are taken. See also construction hole.
Polishing
Abrasive process in which the surface created takes on a bright reflective finish, scratch-free to the unaided eye.
Powder coating
100% solids coating applied as a dry powder and subsequently converted into a film with heal.
Prefinished material
Stock which has been painted or plated prior to fabrication or stamping.
Press
A machine having a stationary bed or anvil and a slide (ram or hammer) which has a controlled reciprocating motion toward and away from the bed surface and at right angle to it. The slide is guided in the frame of the machine to give a definite path of motion.
Press attachment
A bed mounted device on a slide forming machine used for punching, piercing and other press operations.
Press bed
The stationary and usually horizontal part of a press that serves as a table to which a bolster plate or lower die assembly is mounted.
Press brake
An open-frame single-action press used to bend, blank, corrugate, curl, notch, perforate, pierce, or punch sheet metal or plate.
Press capacity
The rated force a press is designed to exert at a predetermined distance above the bottom of the stroke of the slide.
Press forming
Any sheet metal forming operation performed with tooling by means of a mechanical press or hydraulic press.
Press in fastener (PEM)
Fasteners utilizing self-clinching, broaching, or flaring technology combined with press tools to permanently attach to sheetmetal, providing strong and reusable attachments.
Press load
The amount of force exerted in a given forging or forming operation.
Press ram
See press slide.
Press section
A device that is built into a slide forming machine used for punching, piercing and other press operations.
Press slide
The main reciprocating member of a press, guided in the press frame, to which the punch or upper die is fastened. Sometimes called the ram, press ram, slide, plunger, or platen. See slide.
Press tool
A piece of precision-made, mass production, tooling used to cut, bend and shape metal components from flat, coil or sheet material. The components produced could range in size from car roof panels, to small clockwork gears in watches and timepieces.
Prime material
Any material produced that is to-spec with no quality related issues.
Product
The object or material that has had an operation of the class type performed upon it.
Production jigs and fixtures
Precision-made mass production tooling used to safely and accurately position and hold components during a production line process, to allow follow-on operations such as machining, welding, painting, assembly and/or packaging to be undertaken on the component.
Production rate
The production rate is the output-rate of the process. For batch processes, it is measured in number of units per hour, or in total mass per hour of product. For continuous processes, it is measured in total mass or length per hour. Automated processes have higher output rates than their manual counterparts.
Profile grinder
A machine used to grind contour on a steel. Can be used with mounted wheels or carburrs. Also called a diemaker's friend or helper.
Profiling
Machining or grinding the outline of die members.
Programmable back gauges
Stops on metalforming machines which can be adjusted during and between cycles by computer numeric control.
Progressive forming
Sequential forming at consecutive stations with a single die or separate dies.
Projection welding
Using protrusions on one of the two parts to be resistance welded, creating a positive conductance path.
Proof
Any first-off, or prototype for customer approval.
Proportional limit
The greatest stress a material is capable of developing without a deviation from straight-line proportionality between stress and strain.
Prototype
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 roll-over.
Pulse mode
Intermittant surging of power, used in laser cutting, AC-TIG and DC-TIG welding
Punch
The male part of a die-as distinguished from the female part, which is called the die. The punch is usually the upper member of the complete die assembly and is mounted on the slide or in a die set for alignment (except in the inverted die). In double-action draw dies, the punch is the inner portion of the upper die, which is mounted on the plunger (inner slide) and does the drawing. The act of piercing or punching a hole. Also referred to as punching. The punch is the movable part that forces the metal into the die in equipment for sheet drawing, blanking, coining, embossing and the like.
Punch direction
The direction from which a tool or punch enters the workpiece.
Punch press
Machine supplying compression force for reshaping materials.
Punch radii
The punch corner radius and/or the punch nose radius.
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.
Punch
1) The male steel on a brake press.
2) The male portion of the cutting tool set on a punch press.
Punching
1) Shearing holes in sheet metal with punch and die.
2) The die shearing of a closed contour in which the sheared out sheet metal part is scrap.
3) Forming metal components using a punch.
Q
Quarter hard
Referring to the temper of an alloy, characterized by tensile strength midpoint between fully annealed and half-hard temper.
Quick change inserts
Tool sections or parts that may be changed without removing the entire tool from the press.
R
Ram
Driven (movable) part of a metalforming machine.
Rapid prototyping
This includes a number of rapidly evolving techniques for making prototypes and models quickly thus allowing designers to check their designs and make any necessary changes before investing in expensive tooling. A CAD model of the part is required and the model is usually built layer by layer.
Relief
Clearance obtained by removing metal either behind or beyond the cutting edge of a punch or die. Also called undercut or back-off.
Repositioning
Operation in punch 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 (CNC).
Reproducibility
Extent to which parts from multiple lots are identical.
Reservoirs
A tank used to store fluid for a hydraulic system - this maintains the fluid at an even temperature by allowing circulation and cooling from the tank sides.
Reset
The realigning or adjusting of dies or tools during a production run; not to be confused with the setup that occurs before a production run.
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.
Reverse drawing
Redrawing of a sheet metal part in a direction opposite (mirror) to that of the original drawing.
Reverse flange
A sheet metal flange made by shrinking, as opposed to one formed by stretching.
Revision
A subsequent part drawing usually denoting new corrected or improved version.
Revision description
A written notice describing the nature of changes to a drawing.
Rib
A long V-shaped or radiused indentation used to strengthen large sheet metal panels. A long, usually thin protuberance used to provide flexural strength to a forging (as in a rib-web forging).
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.
Rod
A solid round section 9.5 mm (3/8') or greater in diameter, whose length is great in relation to its diameter.
Roll form
A metal shape that has been processed using roll forming.
Roll forming
A continuous bending operation in the metal forming process, 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 over
The 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 pull down.
Rolling
A term applied to the operation of shaping and reducing metal in thickness by passing it between rolls which compress, shape and lengthen it following the roll pattern.
Rolling mills
Equipment used for rolling down metal to a smaller size or to a given shape employing sets of rolls tie contours of which determine or fashion the product into numerous intermediate and final shapes, e.g., blooms, slabs, rails, bars, rods, sections, plates, sheets and strip.
Rough blank
A blank for a forming or drawing operation, usually of irregular outline, with necessary stock allowance for process metal, which is trimmed after forming or drawing to the desired size.
Roundness
Extent to which a feature is circular.
Run
1) Sag or accumulation in a paint or finish film prior to curing.
2) The extent of a work order in production, with reference to a specific part.
Run out flange
Feature on a formed part which is designated by the designer to absorb the tolerance accumulations created by multiple forming operations.
Run stamps
Stamps used in a die to stamp the date the part was run. Normally this is the Calendar or Ordinal date.
Running clearance
The amount of, clearance designed in a die between two mating steels to allow for stock thickness at bottom of press stroke.
S
Salt spray test
An accelerated corrosion test in which the metal specimens usually coated steel are exposed to a fine mist of salt water solution either continuously or intermittently. Spray is usually 5% NaCl.
Scale
Thick oxide coating on material normally associated with hot working. Deposit formed from solution directly in place upon a confining surface.
Scale weight
Used alternately with actual weight.
Scaling
A process used for spotting large contoured areas by using a spotting stick. See also spotting stick.
Scallop
Edge condition resulting from nibbling a feature in a turret press.
Scoring
The marring or scratching of any formed part by metal pickup on the punch or die. The reduction in thickness of a material along a line to weaken it intentionally along that line.
Scrap
Leftover, unused material relegated to recycling.
Screw press
A high-speed press in which the ram is activated by a large screw assembly powered by a drive mechanism.
Section (normal and extreme)
Units: mm (SI), inches (Imperial) The 'normal' range of section thickness which lies within the capacity of the process. As with mass, an 'extreme' range is also stored. Minimum section is determined by considerations of fluid flow in castings, of plastic constraint in forgings and so on. It can usually be reduced by machining.
Sections
See details.
Segment die
Same as split die.
Selective perforation
Hole or slot pattern over a specific portion of a workpiece, normally used for ventilation purposes.
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.
Semi-perfs
See half shear.
Sever
To forcibly part or separate a discrete portion from a body of material. See cut.
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.
Shape control
Ability to produce material to a given geometric flatness standard. See flatness.
Shape defect
Geometric non-uniformity of a strip, such as bent strip, coil set, center buckle, wavy edge, etc.
Shaving
A secondary shearing or cutting operation in which the surface of a previously cut edge is finished or smoothed by removing a minimal amount of stock.
Shear
A type of cutting operation in which the metal object is cut by means of a moving blade and fixed edge or by a pair of moving blades that may be either flat or curved. The type of force that causes, or tends to cause, two contiguous parts of the same body to slide relative to each other in a direction parallel to their plane of contact.
Shear strength
The maximum shear stress a material can sustain. Shear strength is calculated from the maximum load during a shear or torsion test and is based on the original dimensions of the cross section of the specimen.
Shearing
Cutting force applied perpendicular to material causing the material to yield and break.
Sheet
Any material or piece of uniform thickness and of considerable length and width as compared to its thickness. With regard to metal, such pieces under 6.5 mm (1/4 in.) thick are called sheets, and those 6.5 MM (1/4") thick and over are called plates. Occasionally, the limiting thickness for steel to be designated as sheet steel is No. IO Manufacturer's Standard Gage for sheet steel, which is 3.42 mm (0.1345") thick.
Sheet forming
The plastic deformation of a piece of sheet metal by tensile loads into a three-dimensional shape, often without significant changes in sheet thickness or surface characteristics. Compare with bulkforming.
Sheet products
1) Hot Rolled - Uncoated, heavy gauge, fully processed in Strip Steel, never cold reduced at Tandem Mill.
2) Cold Roll - Uncoated, heavy gauge, primarily processed in Strip Steel, although some goes to the Tin Mill, always cold reduced at Tandem Mill.
3) Galvanized - "Bath" coated with zinc, heavy gauge, primarily processed thru Strip Steel &amkp; Sheet Mill, majority is cold reduced at Tandem Mill.
4) Galvannealled - "Bath" coated with zinc, then "Air Knife" thinned and reheated. Also called Satin Coat, Wipe Coat, and Light Coat.
Shielding gas
Inert gas used for oxidation protection during welding.
Shot blasting
Cleaning surface of metal by air blast, using metal shot as an abrasive.
Shunting
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.
Silkscreening
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.
Single-action press
A forming press that operates with a single function, such as moving a punch into a die with no simultaneous action for holding down the clank or ejecting the formed work.
Sinkhole
In welding, a dimple on the surface of stock caused by shrinking of the weld during cooling.
Slit edge
The relatively smooth edge produced from side trimming or slitting. See mill edge.
Slug
The metal removed when punching a hole in a forging; also termed punchout. The forging stock for one workpiece cut to length. See also blank.
Slug pulls
Surface defects caused by the slug material being pulled back to the topside of the workpiece and indented into the metal surface on the successive stroke by the punch.
Spalling
The breaking off of flake - like metal particles from a metal surface.
Spangle free
A galvanized product in which the spangle formation has been suppressed; accomplished by eliminating Antimony and Lead in the molten zinc bath during the production of Hot Dipped Galvanized. Galvannealed is always spangle free.
Spatter
In welding, droplets of matter deposited as contaminants.
Spear punching
The process of cutting or tearing a hole in metal, which does not generate a slug. Instead, the metal is pushed back to form a jagged flange on the backside of the hole. Also called spearing.
Spearing
The process of cutting or tearing a hole in metal, which does not generate a slug. Instead, the metal is pushed back to form a jagged flange on the backside of the hole. See spear punching or extruding.
Spinning
The forming of a seamless hollow metal part by forcing a rotating blank to conform to a shaped mandrel that rotates concentrically with the blank. In the typical application, a flat-rolled metal blank is forced against the mandrel by a blunt, rounded tool; however, other stock (notably, welded or seamless tubing) can be formed. A roller is sometimes used as the working end of the tool. The procedure of making sheet metal discs into hollow shapes by pressing the metal against a rotating form (spinning chuck) by a tool.
Split die
A die made of parts that can be separated for ready removal of the workpiece. Also known as segment die.
Spot face
Circular flat surface as a bearing area for hardware. Also refers to the smooth area around a hole for a fastener. Also called sump.
Springback
Elastic recovery that follows plastic deformation when the flanging load is removed.
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 | |
