Aluminum Glossary

Definitions of words and meanings of abbreviations related to aluminum extrusion and aluminum anodizing.
Some definitions © 1999 by the AEC; used with permission.

AMS Abbreviation for Aerospace Material Specification.
ANSI Abbreviation for American National Standards Institute.
ASD Abbreviation for Aluminum Standards and Data book published by The Aluminum Association.
ASTM Abbreviation for American Society for Testing and Materials.
AWS Abbreviation for American Welding Society.
Adhesion Bonding strength. The attraction of a coating to the surface to which it is applied.
Adjustable Cores &
Die Plate Die
Die with inserts in the core and/or plate that can be adjusted to compensate for deflection or replaced because of wear.
Age Hardening An aging process that results in increased strength and hardness.
Aging Precipitation from solid solution resulting in a change in properties of an alloy, usually occurring slowly at room temperature (natural aging) and more rapidly at elevated temperatures (artificial aging).
Alloy A substance with metallic properties, composed of two or more chemical elements of which at least one is a metal. More specifically, aluminum plus one or more other elements, produced to have certain specific, desirable characteristics.
Alumina Aluminum oxide produced from bauxite by a complicated chemical process. It is a white powdery material that looks like granulated sugar. Alumina is an intermediate step in the production of aluminum from bauxite, and is also a valuable chemical on its own.
Aluminum A silver-white soft metal, noted for its lightness, high reflectivity, high thermal conductivity, nontoxicity, and corrosion resistance. It is the most abundant metallic element, comprising about 1/12th of the earth's crust. It is never found in nature as an elemental metal, but only in combination with oxygen and other elements. In ordinary commercial and industrial use, the word aluminum is often understood to mean aluminum alloy, rather than the pure metal.
Aluminum Oxide A chemical compound of aluminum with oxygen, which forms immediately on an unprotected aluminum surface exposed to air. Unlike iron oxide (the rust which forms on steel) aluminum oxide does not flake off, but forms a protective layer that blocks further oxidation and so protects the integrity of the metal. It is transparent and does not alter the appearance of the aluminum surface.
Angularity Conformity to, or deviation from, specified angular dimensions in the cross section of a shape or bar.
Annealing A thermal treatment to soften metal by removal of stress resulting from cold working or by coalescing precipitates from solid solution.
Anodizing Forming a coating on a metal surface produced by electrochemical treatment through anodic oxidation. This process may be used to increase the protective effect of aluminum's transparent natural oxide surface. It may also be given a decorative coloration.
Aperture In an extrusion die, the shaped opening through which the heat-softened metal is forced and which gives the extruded product its cross-sectional shape. Also called the orifice.
Architectural Finish An architectural finish is a standard finish characterized by a uniform appearance. This finish is most often specified for exposed surfaces.
Assembly Fit Refers to two parts designed for mating assembly and requiring exact dimensions and contours to assure a proper fit.
Assignable Cause A factor contributing to variation that is feasible to detect and identify.
Backer (back-up plate) A tool , or reinforcing part, which presses against the outer surface of an extrusion die, supporting it against the pressure of the extruding metal. The backer has an opening larger than the die aperture, allowing the extruded product to emerge without marring its soft surface.
Back Taper (Relief) Cut-away portion of die beginning at breakaway point to the die exit either angled or undercut (stepped back) for back clearance.
Bake The curing of paint at an elevated temperature for a specific period of time, allowing the paint to become hard and dry.
Bar A solid extrusion that is long in relation to cross section, which is square or rectangular (excluding plate or flattened wire) with sharp or rounded corners or edges; or is a regular hexagon or octagon; and in which at least one perpendicular distance between parallel faces is 0.375 inch or greater. (Smaller sizes are classified as wire.)
Bauxite One of the ores from which alumina is extracted and from which aluminum is eventually smelted. Bauxite usually contains at least 45 percent aluminum oxide (alumina), and the best grades have a low silica content. About four pounds of bauxite is required to produce one pound of aluminum.
Beam The principal horizontal load-bearing member of a structure.
Bearing The surface of the extruding aperture, at right angles to the die face, that controls metal flow and to some extent speed of flow which is also the conforming surface along which the aluminum flows.
Bell Electrostatic spray device whose paint applicator is bell-shaped, atomizing paint off its edge.
Belly The area of a liner that has an increased inside diameter from nominal, appearing convex (may be caused by a weak container).
Billet, Extrusion May be solid or hollow in form, commonly cylindrical, used as the final length of material charged into the extrusion press cylinder. It is usually a cast product, but may be a wrought product or sintered from powder compact.
Billet Container The part of an extrusion press into which the billet to be extruded is placed.
Blank A piece of metal cut or formed to regular or irregular shape for subsequent processing such as by forming, bending, or drawing. The piece of sheet stock cut out by blanking die. It will subsequently be drawn into a cup or end shell.
Blending The machining of the transition in the bearing length from long to short.
Blister A raised area on the surface of an extruded product due to subsurface gas expansion during extrusion or thermal treatment.
Blistering A defect in the paint film appearing as bubbles, usually caused by the expansion of air, solvent vapor, or moisture trapped beneath the film.
Blocking The use of graphite blocks to support the emerging extrusion as it exits the die.
Bloom A semi-finished hot rolled product, rectangular or square in cross section, produced on a blooming mill.
Blow Hole A blister that has ruptured and may produce a void. See also Blister .
Bolster (die block) A tool , or reinforcing part, which supports the backer -- which, in turn, supports an extruding die against the pressure of extrusion.
Bow Longitudinal curvature of rod, bar, profiles (shapes), and tube. Bow is measured after allowing the weight of the extrusion to minimize the deviation. Bow can be caused by a non-uniform extrusion rate across the cross section resulting in one portion of the extrusion being longer than the other or non-uniform contraction during quenching.
Bow, Lateral Deviation from straight of a longitudinal edge.
Bow, Longitudinal Curvature in the case of sheet or plate in the rolling direction, along the length of an extrusion.
Bow, Transverse Curvature across the rolling direction of sheet or plate, across the width of an extrusion.
Breakaway Point Is usually formed by the step where die undercut starts and bearing surface ends and is also where the extrusion leaves the bearing.
Breakout Pressure The initial pressure required to start metal flow through the extrusion die.
Breakthrough The point in time when the billet emerges from the exit side of the die as an extruded profile.
Bridge In extrusion: the part of an extrusion bridge die that supports a void-forming mandrel. During extrusion, the metal divides and flows around the bridge, reuniting as it is extruded through the die orifice. The resulting weld line can be detected upon microscopic examination, but the extrusion appears functionally and visually seamless.
Bridge Type Die A die having a stationary core or mandrel which is held in place by core supports or webs (bridge) bolted to the back of the die. The die contains a weld chamber so that when the billet is pushed the metal divides to flow around the core supports and welds together in the welding chamber before passing through the die. See Porthole Die and Spider Die . Bridge dies normally have unenclosed ports which protrude into the container liner.
Bridging (Webs Network) The network of support webs which hold in place the internal surface forming portion of the mandrel, created when the ports are machined into the mandrel.
Bridging (Design Purpose) Is used to reduce pressure on critical tongue areas of a semi-hollow or hollow die.
Bright Dipping Chemical polishing of aluminum, often by treatment with a mixture of nitric acid and phosphoric acid, yielding a mirror-shiny (specular), highly reflective surface. It is almost always followed by anodizing to protect the surface and provide some choice of colors.
Brinell Hardness See Hardness , Brinnell .
Broken Die A deviation from the desired cross section due to the absence of a certain portion of the die used to extrude the profile (shape).
Buckle A distortion of the surface of the metal.
Buffing A mechanical finishing operation in which fine abrasives are applied to a metal surface by rotating fabric wheels for the purpose of developing a lustrous finish.
Burr A thin ridge of roughness left by a cutting operation such as slitting, trimming, shearing, blanking, or sawing.
Burrs Tiny, almost microscopic shards of die steel protruding into the die aperture (opening), usually from either the entry or exit edge of the bearing. They are typically formed during the manufacture of the die but can also be formed by striking the die opening with a hammer, dies bumping together during handling or other abnormal impacts to the die face.
Bus Bar A rigid electric conductor in the form of a bar.
Butt The unextruded portion of the billet remaining in the container after the extrusion cycle is completed. The butt varies in thickness depending upon the alloy, die configuration, and extruded profile characteristics.
Butt End The residual portion of an extrusion billet that is not formed through the die at the end of the extrusion cycle.
Butt Weld The welding of two sections that butt against each other, end to end.
CAD Computer Assisted Design. The use of computer programs to generate, analyze and modify designs. Extrusion dies and their supporting tools, for example, may be designed with the aid of computers.
CAM Computer Assisted Manufacturing. The use of computers to monitor, regulate and control manufacturing processes.
Cap The outer part of a hollow die, which shapes the outside of a hollow extrusion.
Cap Bearings The surfaces in the aperture of a hollow die which form the outside contour of a hollow extrusion. These surfaces are located on that part of a hollow die which fits against the web or bridge base of the mandrel and are on the same plane as the mandrel bearing. See Bearings .
Cast To form a molten material into a desired shape by pouring into a mold and letting it harden.
Casting Alloy An alloy formulated for casting.
Caustic (Sodium Hydroxide, NaOH and derivatives). The active ingredient in an alkaline bath, generally with a pH higher than 10, which removes aluminum from used extrusion dies by etching. The primary ingredient, Caustic Soda (NaOH), dissolves the aluminum alloy by chemical reactions with no affect on the die steel.
Cavity See Prechamber , Pocket , Piastrina , and Weld Pocket. An area in the entry side of the die which serves to control flow of metal and in a solid die it permits a profile to be continuously extruded as metal from the succeeding billet face is welded to the previous rear face remaining in the cavity after shearing. The pocket generally follows the contour of the profile with milled depths varying from 0.040" to 1" or more depending upon its function.
Cell In aluminum production: the electrolytic reduction cell, commonly called a pot , which alumina dissolved in molten cryolite is reduced to metallic aluminum. A series of cells connected electrically is called a pot line.
Center The difference in thickness between the middle and edges (average) of a sheet.
Chalking A white powdery deposit on the surface of the exposed paint film caused by weathering.
Chamfer A bevel at the apex of an angle on a machined part to allow clearance and prevent interference when assembled with another machined part. The interference may occur from dirt, burrs, or incidental marring of the die surface. A chamfer aids in the assembly of closely fit machined parts. Large chamfers are sometimes used on the webs of hollow die entry ports to reduce the initial contact area between die and billet.
Chatter A surface defect consisting of alternating ridges and valleys at right angles to the direction of extrusion.
Chatter Mark Numerous intermittent lines or grooves that are usually full width and perpendicular to the extrusion direction.
Chemical Milling Removing metal from a piece by controlling chemical etching.
Chemical Polishing Improving the surface luster of metal by chemical treatment.
Choke The angle filed on a bearing surface at the point where bearing and die face meet (where aluminum enters aperture). Choke length and choke angle may vary independently. The angle of choke generally falls between 1 2 degrees to 5 degrees.
Circumscribed Port Entry An imaginary circle defining the maximum port entry for a given container liner where this diameter is typically approximately 75% to 90% of the die diameter.
Circumscribing Circle The smallest circle that will completely enclose the cross section of an extruded shape.
Cladding A protective layer of pure aluminum or appropriate alloy to increase corrosion resistance and/or to allow for brazing, applied to the surface of aluminum.
Cleanout Block A circular tool or block used for scraping the aluminum skull from the container liner's inside wall. The cleanout block diameter is greater than that of a dummy block and is sometimes called a scavenger block or cleanout disk.
Cleanout Plate Is similar to a cleanout block except that it is made from 2 or 3/4 inch mild steel plate.
Coating Continuous film on the surface of a product.
Coating, High or Low
Cobble (1) A jamming of the mill by aluminum product while being rolled. (2) A piece of aluminum which for any reason has become so bent or twisted that it must be withdrawn from the rolling operation and scrapped.
Coefficient of Thermal Expansion The relative rate at which a substance expands on heating, compared to a standard rate.
Cold Working Plastic (i.e., permanent) deformation of metal at such temperature and rate that strain-hardening occurs.
Coloring A finishing process, or combination of processes, which alters the appearance of an aluminum surface via coating, chemical, and/or mechanical operations.
Composite Alloy An aluminum alloy containing relatively large amounts of two or more other elements.
Composite Joint A joint that is both welded and joined mechanically.
Compressive Strength Strength to resist outside pressure (as distinguished, for example, from bending or stretching forces).
Concentricity Conformance to a common center as, for example, the inner and outer walls of round tube.
Condenser Tube The term Heat-Exchanger Tube is preferred, unless specific reference to a condenser application is intended and purpose is to dissipate heat as efficiently as possible.
Conductivity The ability of a substance to transmit heat, light or electricity. Aluminum has high electrical and thermal conductivity, making it useful in a wide range of electrical and heat-exchanging applications.
Conduit A tube used to protect electric wiring. See also Tubing, Electrical Metallic .
Conduit, Rigid Conduit having dimensions of ANSI Schedule 40 pipe in standardized length and threaded ends.
Container The steel cylinder, usually fitted with a removable liner, having an inside diameter slightly larger than the billet to be extruded which holds and confines the billet during the extrusion cycle. Its length may vary with the press tonnage rating and manufacturer.
Container Liner The removable, replaceable cylindrical unit of press tooling which holds or confines the billet during the extrusion cycle.
Container Seal The interface between the container and the die. There must be sufficient clearance between the outer edge of the die port and the inner edge of the container opening to prevent extrusion of the billet skin or skull.
Container Wall Clearance The difference in dimensions between the billet diameter and container liner internal diameter.
Contour That portion of the outline of a transverse cross-section of an extruded profile that is represented by a curved line or curved lines.
Contour Correction Rolling An operation in which the extrusion is passed between rollers to adjust profile dimensions so that specified tolerances in angularity, cross-sectional space dimensions, flatness, and contour are achieved. Bow and twist may also be minimized or eliminated by contour rolling.
Conversion Coating A chemical layer formed on the metal in the pretreatment process which aids in paint adhesion and corrosion resistance.
Corrosion The deterioration of metal by chemical or electrochemical reactions with substances in its environment.
Corrosion, Galvanic Corrosion associated with the current of galvanic cell consisting of two dissimilar conductors in an electrolyte or two similar conductors in dissimilar electrolytes. Aluminum will corrode if it is anodic to the dissimilar metal.
Corrosion, Pitting Localized corrosion resulting in small pits or craters in a metal surface.
Corrosion, Water Stain Superficial oxidation of the surface with a water film, in the absence of circulating air, held between closely adjacent metal surfaces.
Coupon A piece a metal from which a test specimen may be prepared.
Covering Area Yield expressed in terms of a given number of square inches in a pound. For metric units, use square meters per kilogram.
Cratering A paint film defect appearing as small, round bare spot on the painted part. This may be caused by gassing, incompatibility, or silicones.
Crazing A macroscopic effect of numerous surface tears, transverse to the rolling direction, which can occur when the entry angle into the cold mill work rolls is large.
Crease A sharp deviation from flat in the sheet which is transferred from processing equipment subsequent to the roll bite.
Creep The strain in a metal that results from continuing constant stress.
Crosshatch Test to demonstrate adhesion characteristics of a paint or powder coated surface, performed by scribing a crosshatch pattern at specified intervals.
Cryogenic Pertaining to very low temperatures. Aluminum gains strength as temperature is reduced, making it an appropriate material for cryogenic applications.
Cure The process of converting a liquid paint to a solid, durable film, usually accomplished by the action of heat and catalysts.
Curl An undesirable condition caused by uneven rates of absorption or evaporation of moisture, uneven rates of contraction or expansion, or internal stresses in the material. Curl is most prevalent in laminated structures where the components have differing physical properties.
Dead Metal Zone An area of inactive metal that generally remains dormant and stagnant throughout the extrusion process. These zones are inherent to the process and are normally found inside the mandrel of a hollow die and in direct extrusion inside the container adjacent to the die.
Dead Soft Fully annealed, the softest form of a metal, the temper of aluminum.
Deburring Removing burrs, sharp edges, or fins from metal parts by filing, grinding, or tumbling.
Deep Drawing Forming a deeply recessed part by forcing sheet metal to undergo plastic flow between dies, usually without substantial thinning of the sheet.
Defect A defect is anything that renders the aluminum unfit for the specific use for which it was ordered.
Deflection The distortion or bending of the die or components thereof. Insufficient support of die will cause it to deflect, lessening the effectiveness of the bearing; also termed dishing, caving, and sagging.
Density Weight per unit of volume (for example pounds per cubic foot). The density of aluminum is only about one-third that of steel, and this weight-saving characteristic is one of aluminum's best-known advantages.
Dent A sharply defined surface impression on the metal which may be caused by a blow from another object.
Dent, Repeating Repeating depression caused by a particle adhering to a rotating roll over which the metal has passed.
Depth of Fusion The depth to which base metal melts during welding.
Detection A past-oriented strategy that attempts to identify unacceptable output after is has been produced and then separate it from the good output.
Diametrical Temperature The temperature of a circular object, measured from the center to the edge (average).
Die In extrusion a tool with an opening through which heated aluminum is forced by pressure, taking on that cross-sectional shape.
Die Assembly In an extrusion press, the die and its associated tooling.
Die Face The surface of an extrusion die facing the billet.
Die Holder The press component which is located between the container and press platen to retain the extrusion die and its components. It may take many different forms and added functions depending upon its design. The holder can be unlocked and the die withdrawn for the removal of butt and scrap.
Die, Hollow A steel extrusion tool which forms extruded closed profiles containing one or more voids such as rectangular tubing. The tool generally consists of a die cap which generates the outer surface of the profile and the mandrel or core which generates the inside contour. Hollow or semi-hollow profiles are produced usually with either bridge, porthole or spider (taper seal) type dies or variants thereof. Extruded sections produced on such dies have seams or longitudinal weld lines, due to the metal flow around the web supports (bridges) that hold the mandrel. The latter determines the inside contour of the profile being extruded. After flowing around the supports, the metal is fused in a weld chamber before passing through the die (die cap) proper.
Die Kinks The sectional irregularities caused by an uneven extrusion rate, or by material either not being led from the die in a uniform manner or being adequately supported.
Die Lines A longitudinal depression or protrusion formed on the surface of drawn or extruded material. Die lines are present to some degree in all extrusions and are caused by a roughening of the die bearing.
Die Number The number assigned to a die for identification and cataloging purposes, and which usually is assigned for the same purpose to the product produced from that die.
Die Ring A cylindrical sleeve that holds the die and backer in axial relationship to each other.
Die, Semihollow A circular steel extrusion tool which forms an open profile with a high tongue ratio. Generally this tongue ratio is greater than three to one. This type of die is similar to a hollow die. The tongue is protected by a web or bridge which reduces the billet pressure. When possible, for maximum support the tongue should be bolted to the web.
Die Slide The extrusion press component located between the container and press platen. It supports, aligns to the press and retains the tooling (die, backer, bolster, sub-bolster, etc.) for the specified profile, as a unit. It may be designed to facilitate butt shearing and to provide die accessibility for replacement and repairing.
Die, Solid A steel disk, with one or more orifices or apertures, of similar cross-section and contour as the desired product, through which metal is forced forming open profiles such as bar, channel and angle.
Die Stop A defect resembling a weld around the entire extruded section, caused by stopping a press during extrusion and then restarting it.
Die Tool Assembly The various components making up the assembly within the tool carrier or Die Slide. A typical example would be (from front to rear): die and backer enclosed in a die ring, bolster and possibly a sub-bolster or spacer.
Die Weld A region in extruded hollow profiles created by two streams of metal within the die joining themselves in the weld chamber around the mandrel of a hollow type die. Die welds are generally present in all extruded hollow profiles and in most cases are not visible.
Dimensional Allowance The specified difference in size between mating parts.
Dimensional Stability The ability of an object to retain its original shape under varying physical conditions.
Disc (1) A circular blank fabricated from plate, sheet, or foil, from which a central concentric area has been removed. (2) An electrostatic paint application shaped like a disc which atomizes paint utilizing centrifugal force off the edge of the disc.
Discontinuities Abnormalities such as cracks, laps, folds, cold shuts, inclusions, segregation and porosity. Voids of any kind.
Distortion Any deviation from the desired shape or contour.
Dove-tail An interlocking connection frequently used for the assembly of interconnecting extrusions; it is assembled by a sliding action.
Draft Taper on the sides of a die or mold impression to facilitate removal of forgings, castings or patterns from dies or molds.
Drawing Stock A hot worked intermediate solid or tubular product of uniform cross section along its whole length, supplied in coils and of a quality suitable for drawing into tube or wire.
Drawn Product A product formed by pulling material through a die.
Ductility The property that permits permanent deformation before fracture by stress in tension.
Duct Sheet Coiled or flat sheet in specific tempers, widths and thicknesses, suitable for duct applications.
Dummy Block A tight-fitting steel block placed between the ram and the billet in an extrusion press to prevent metal from leaking backward along the ram during extrusion.
E.C. (or EC) Alloy or Grade Electrical conductor aluminum, an alloy specifically formulated for good electrical conductivity; it is about 99.5 percent aluminum. Typically AA1350 alloy.
EDM (Electrical Discharge Machining) A process that utilizes high frequency pulsating DC current in the presence of a dielectric to erode tool steel. The Ram or Plunge EDM process is utilized for burning relief into the back of the die, or burning the shape into the mandrel core. Wire EDM is utilized to cut die openings in dies.
Eccentricity Deviation from a common center, as, for example, the inner and outer walls of a round tube. The difference between the mean wall thickness and minimum or maximum wall thickness at any one cross section. The permissible degree of eccentricity can be expressed by a plus and minus wall-thickness tolerance.
Edge, Broken (Cracked) Edge(s) containing crack, split, and/or tear which may be caused by an inability to deform without fracturing.
Edge, Damaged Edge of a coil that has been bent, torn, or scraped by an object.
Edge, Dropped A continuous, downward edge deflection.
Edge, Liquated Surface condition remaining after portions of a side of an as-cast rolling ingot deforms enough during hot rolling to become top and/or bottom surface(s) of the rolled product at an edge.
Elastic Deformation A temporary dimensional change induced by stress. The body returns to its original dimensions when the stress is removed if its elastic limit has not been surpassed.
Elasticity The ability of a material or body to return to its original shape and dimensions after being deformed by stress.
Elastic Limit The maximum stress that a body can withstand without permanent deformation.
Electrical Conductivity The capacity of a material to conduct electric current. For


aluminum, this capacity is expressed as a percentage of the International Annealed Copper Standard (IACS), which has a resistivity of 1/58 ohm-mm2/meter at 68 º F and an arbitrarily designated conductivity of unity.
Electrical Resistivity The electrical resistance of a body of unit length and unit cross-sectional area or unit weight. The value of 1/58 ohm-mm2/meter at 68 º F is the resistivity equivalent to the International Annealed Copper Standard for 100 percent conductivity. This means that a wire of 100 percent conductivity, 1 meter in length and 1 square millimeter in cross-sectional area would have a resistance of 0.017241 ohms at 68 degrees F.
Electrochemical Pertaining to chemical reactions induced by an electric current such as electrolysis or electroplating.
Electrodeposition Application of a coating by immersing the parts in a bath of water containing resin, electrolytic stabilizers and pigments, an electric current is passed through the bath, using the parts as anodes, plating them with resins and color.
Electrolysis The separation of a chemical compound into its components by passing an electric current through it.
Electrolyte A dissolved or fused substance capable of conducting an electric current, examples include the molten solution electrolyzed in an aluminum reduction cell, or the acid solution in a wet-cell battery.
Electroplating Depositing a thin layer of a metal, usually copper, tin or silver, on the surface of another metal by electrifying the metal to be plated in an electrolyte containing the plating metal.
Electrostatic Application A system of applying paint in which the paint droplets or powder particles are given an electrical surface charge resulting in their attraction to a grounded workpiece. Higher transfer efficiency, better wrap and penetration, finer atomization and less overspray are distinct advantages.
Electrostatic Spraying Application of a coating by applying a static electricity charge to the droplets of a spray and an opposite charge to the part being sprayed, which then attracts the droplets directly to its surface.
Elongation The percentage increase in distance between two gauge marks that results from stressing the specimen in tension to fracture. The original gauge length is usually 2 inches for flat specimens and round specimens whose diameter is 0.5 inch, or four times the diameter for specimens where that dimension is under 0.5 inch. Elongation values depend to some extent upon size and form of the test specimen. For example, the values obtained from sheet specimens will be lower for thin sheet than for thicker sheet.
Embrittlement Reduction in the normal ductility of a metal, due to physical or chemical change.
Emissivity The relative ability of a material to radiate energy per unit of surface area expressed as a ratio to the radiation rate of an ideal black body of identical area and temperature.
Endurance Limit The limiting stress below which a material will withstand a specified large number of cycles of stress.
Equivalent Round The diameter of a circle having a circumference equal to the outside perimeter of other than round tube.
Etchant Chemical solutions used to change the metal surface for cleaning, examination or for finishing.
Etching Shaping or texturing a metal surface by controlled corrosive action.
Exposed Surface Any face of an extruded profile which is exposed to view or other critical end-use aspects.
Extraction The general process of separating a metal from its ore.
Extrude To force material through a die by pressure.
Extruded Length The length of a profile (section) extruded in a single push.
Extruded Profile A profile usually of constant cross section brought to final dimensions by extruding. The preferred term describing an extrusion formerly termed an extruded shape .
Extruded Shape Any aluminum extrusion other than rod, bar, or tube.
Extrusion Billet The starting stock for the extrusion operation. Extrusion billet is a solid or hollow form, commonly cylindrical and is the length charged into the extrusion press cylinder. It is usually a cast product but may be a wrought product or powder compact.
Extrusion Butt End Defect A longitudinal discontinuity in the extreme rear portion of an extruded product, which is normally discarded.
Extrusion Defect A cone-shaped abnormality such as a cavity in an extruded product (ring in a hollow profile or tube) formed in the extreme rear portion, if extruded too far.
Extrusion (Direct) The method of extruding wherein the die and ram are at opposite ends of the billet and the product and ram travel in the same direction.
Extrusion (Indirect) The method of extruding where the die is at the ram end of the billet and the product travels through the hollow ram and in the opposite direction.
Extrusion Ingot A cast form that is solid or hollow, usually cylindrical, suitable for extruding. See also Fabricating Ingot.
Extrusion Ingot (Scalped) A cast solid or hollow extrusion ingot which has been machined on the outside surface. Scalped billets are normally used with the indirect extrusion process.
Extrusion Log The starting stock for extrusion billet. Extrusion log is usually produced in lengths from which shorter extrusion billets are cut.
Extrusion Pressure That force employed to cause billet metal flow through a die.
Extrusion Seam A region in extruded hollow profiles observed after creating two streams of metal and rejoining them around the mandrel of a porthole or bridge die.
Extrusion Speed The velocity or rate at which an extrusion exits from the die usually expressed as feet per minute.
Extrusion Tools The auxiliary equipment required to produce extrusions, which is not an integral or fixed part of the extrusion press. Tools consist principally of container, dies, die backers, dummy blocks, etc.
Fabricate To work a material into a finished state by machining, forming or joining.
Fabricating Ingot A cast form suitable for subsequent working by such methods as rolling, forging, extruding, etc.
Fat Edge An application defect where too much paint accumulates along a square edge or corner of the part, often evidenced by higher gloss or blistering.
Fatigue The tendency for a metal to break under conditions of repeated cyclic stressing considerably below the ultimate tensile strength.
Fatigue Strength The maximum stress that a metal can sustain for a specified number of cycles without failure.
Faying Surface The surface of a piece of metal in contact with another to which it is, or will be, joined.
Feed Pertains to the amount of aluminum directed to a specific area of an extrusion die, generally achieved by adjusting the port size.
Feeder Die A die design which permits through certain design features the extrusion of profiles normally too large for an extrusion press if conventional means were employed or to assist in extrusion of difficult profiles.
Feeder Plate A plate employed in front of the extrusion die to alter the metal billet dimensions permitting extrusion of larger dimensioned product than normally possible or to assist in extrusion of difficult profiles.
Ferrous Pertaining, derived from, or based on iron.
Filler Metal Metal added in making a brazed, soldered or welded joint.
Fillet Generally, a concave junction where two surfaces meet.
Fillet Weld A weld, approximately triangular in cross section, joining two surfaces at right angles to each other.
Film Thickness The depth of applied coating, expressed in mils, i.e. 1/1000 inch.
Fin A thin projection on a forging or casting resulting from trimming or from the metal under pressure being forced into hairline cracks in the die or around die inserts.
Fin Stock Coiled sheet or foil in specific alloys, tempers, and thickness ranges suitable for manufacture of fins for heat-exchanger applications.
Finish In extrusion, the condition, quality or appearance of the final aluminum surface. Aluminum can be finished in a very wide variety of textures and colors.
Finishing Usually secondary operations applied to extrusions to improve product dimensionally or change surface condition (etching) or color (anodizing, plating, painting, buffing, etc).
Fisheye A defect in the paint film appearing as a circular depression resembling a crater but not revealing bare substrate.
Fishtail Die Extruding The utilization of a transition piece of tooling between the container and die (feeder plate), whereby a conventional round billet is forced to assume the elliptical shape of the cavity and opening in the transition piece, before reaching the aperture of the die proper, thus allowing sections to be extruded that are much wider than the container. Such dies can also be made in one piece (feeder die), incorporating the same principles.
Fit The range of clearance or interference between mating parts. The American Standards Association recognizes 33 classes of fits ranging from loose sliding fit to tight force fit.
Fixed Dummy Block A dummy block attached to the ram with self expansion capabilities.
Flag A marker inserted adjacent to the edge at a splice or lap in a coiled product.
Flaking A condition in coated sheet where portions of the coating become loosened due to inadequate adhesion.
Flash A thin protrusion at the parting line of a forging or casting which forms when metal, in excess of that required to fill the impressions, is forced between the die interfaces. Also, metal forced between container and die due to improper seal.
Flash Line A line left on a forging or casting where flash has been removed.
Flat Layout The design method of locating the apertures in a die so that the major axis of each profile is parallel to each other and may be mirrored.
Flatness (1) For rolled products, a distortion of the surface of sheet such as a bulge or a wave, usually transverse to the direction of rolling. Often described by location across width, i.e., edge buckle, quarter buckle, center buckle, etc. (2) For extrusions, flatness (off contour) pertains to the deviation of a cross-section surface intended to be flat. Flatness can be affected by conditions such as die performance, thermal effects and stretching.
Flexibility (1) The capability of a material to be curved, folded, or bent. (2) The ability of a paint to resist chipping, peeling, or cracking after the substrate has been bent, twisted, bowed, or punched.
Floating (Fixed) Dummy Block A fixed dummy block design which has self alignment capabilities.
Flow A term used when referring to the movement of aluminum through the die during the extrusion process.
Flow Line (1) Lines on the surface of painted sheet, brought about by incomplete leveling of the paint. (2) The line pattern revealed by etching, which shows the direction of plastic flow on the surface or within a wrought structure.
Flow Through A forging defect caused when metal flows past the base of a rib resulting in rupture of the grain structure.
Flow Coating Painting a part by directing streams of paint against it and letting excess paint drain into a tank for recirculation. Complicated shapes can be painted this way, but they must be correctly positioned for paint drainage.
Fluorocarbon A stable carbon compound in which hydrogen from a hydrocarbon has been replaced by fluorine. Coatings containing the fluorocarbon PVF2, among the most stable known, are applied by roll coating or spray.
Fluxing The removal of impurities from molten metal in a crucible, furnace, or scrap remelting furnace by bubbling a mixture of gasses up through the melt. The combined chemical and mechanical action carries oxides and other impurities to the top of the melt, forming a scum or dross that is skimmed off.
Formability The relative ease with which a material can be shaped through plastic deformation.
Forming Changing the shape of metal except by shearing or blanking without intentionally altering its thickness.
Fracture A generic term for measure of resistance to extension of a crack.
Frictional Heat That heat imparted to the extrusion or billet as the result of metal movement within the container or through the die.
Galvanic Corrosion Deterioration of a metal caused by the electric current produced when two unlike metals are in contact under certain condition.
Galvanizing An undesirable grainy or spangled condition on the surface of etched or anodized extrusions. This condition is not obvious in mill finish aluminum extrusions but can be revealed by etching or anodizing.
Gas Entrapment A situation that occurs when air is trapped inside the die or container, usually during the dead cycle, as a result of sloppy butt shearing or the upsetting of the billet inside the container.
Gasket A relatively soft sealer often of cork, asbestos, or rubber placed in a joint between two metal parts to prevent leakage through the joint.
Gauge A term previously used in referring to the thickness or diameter of a wrought product. Thickness or diameter is preferred in dimensional descriptions.
German Mandrel Fixed mandrel.
Gloss The degree to which a surface reflects light, generally, the smoother the surface, the higher the gloss.
Grain Flow The directional characteristics of the metal structure after working, revealed by etching a polished section.
Grain Size A measure of crystal size usually reported in terms of average diameter in millimeters, grains per square millimeter, or grains per cubic millimeter.
Grinding Removing material from a workpiece with an abrasive wheel.
Hard Coat Anodizing A combined electrical and chemical finishing process for aluminum that produces a hard, colored, protective film on the surface.
Hardening Increasing the hardness of metal by suitable treatment, usually involving heating and cooling.
Hardness Resistance to plastic deformation, usually by indentation. The term may also refer to stiffness or temper, or to resistance to scratching, abrasion or cutting.
Hardness, Brinell A measure of hardness (resistance to indentation) obtained by applying a load--through use of a ball indenter--and measuring the permanent impression in the material. The hardness value of aluminum alloys is obtained by applying a load of 500 kilograms to a ball 10 millimeters in diameter for 30 seconds; the applied load (in kilograms) is divided by the spherical area of the impression (in square millimeters).
Hardness, Pencil A method of evaluating hardness/adhesion using graded drawing
Hardness, Rockwell An indentation hardness test based on the depth of penetration of a specified penetrator into the specimen under certain fixed conditions.
Heat-affected Zone That portion of the base metal in welding, brazing or flame cutting whose microstructure and physical properties have been altered by the heat.
Heat Checking Horizontal cracks or separation of material usually observed initially on the inside of hollow profiles.
Heat-Treatable Alloy An aluminum alloy that can be hardened to produce desired properties by a controlled cycle of heating and cooling.
Heat Treating Heating and cooling a solid metal or alloy in such a way as to obtain desired conditions or properties. Commonly used as a shop term to denote a thermal treatment to increase strength. Heating for the sole purpose of hot working is excluded from the meaning of this definition -- see Solution Heat Treating .  Aging .
Hiding The ability of a paint to mask the color or pattern of the substrate it covers.
High-Solids Coating Coatings greater than 40% solids by volume, thereby reducing solvent emissions during the application.
Hinge Joint A joint which, when assembled, allows its parts to rotate relative to each other without separating. Hinge joints are extruded as relatively loose slip-fit joints with an open-sided ball-in-socket design.
Hollow Billet A billet prepared for extruding seamless tube or pipe. The outside diameter may be scalped and the inside diameter may be bored or cast hollow to assure sound metal.
Hollow Dies Are extrusion tools capable of forming profiles with voids where such dies are typically classified as either bridge, porthole or spider types. Extruded sections produced on these dies have one or more seams or longitudinal weld lines, due to metal flow around the supports that hold the stub mandrel. The stub mandrel determines the inside contour of the section being extruded. After passing around the supports, the metal is fused in a weld chamber before passing through the die proper.
Hollow Profile An extruded profile, any part of whose cross section completely encloses a void.
Hollow Shape An extruded shape, any part of whose cross section completely encloses a void.
Homogenizing Is a process whereby ingots are raised to temperatures near the solidus temperature and held at that temperature for varying lengths of time. The purposes of this process are to (1) reduce microsegregation by promoting diffusion of solute atoms within the grains of aluminum and (2) Improve workability.
Hook An abrupt deviation from straightness. Hook can be caused by non-uniform metal flow during breakthrough. See also Bow .
Horse Shoe Is a hardened tool steel, horse shoe shaped device intended to hold, position and retain the die ring in the die slide or tool carrier.
Hot Forming Working operations, such as bending, drawing or forging, performed above the softening temperature of the metal.
Hot Hardness The hardness of metals at elevated temperatures. For example in the case of H-11, H-12, and H-13 hot work tool steel hot hardness at 900 º F is lower than at room temperature.
Hot Tears Transverse surface scars or separations along the length of the extruded profile caused by excess speed and/or temperature.
Hot Shortness A condition of the metal at excessively high working temperatures characterized by low mechanical strength and a tendency for the metal to crack rather than deform.
Hot Spot Dark gray or black surface patches appearing after anodizing. These areas are usually associated with lower hardness and coarse magnesium silicide precipitate caused by non-uniform cooling after extrusion.
Hot Working Plastic deformation of metal at such temperature and rate that strain hardening does not occur.
Housing Part of a hollow die that replaces the die ring and is another term for a mandrel when referring to a self-contained die.
Housing Face The surface on the entry of a hollow die. On the aluminum entry side one usually finds ports while on the exit side is located the sealing face.
Hydraulic Press A press in which the ram is activated by fluid pressure.
Impact A part formed in a confining die from a metal slug, usually cold, by rapid single stroke application of force through a punch, causing the metal to flow around the punch and/or through an opening in the punch or die.
Impact Strength The ability of a material to withstand shock loading.
Inclusion Foreign material in the metal or impressed into the surface.
Inclusion, Stringer An impurity, metallic or non-metallic, which is trapped in the ingot and elongated subsequently in the direction of working. It may be revealed during working or finishing as a narrow streak parallel to the direction of working.
Inflation The term associated with hollow profiles that extrude convex rather than flat.
Ingot A cast form suitable for remelting or fabricating. See Fabricating Ingot , Extrusion Ingot , Forging Ingot .
Insulator A material that resists the flow of heat, sound, electricity or another form of energy.
Interference Fit The class of fit in which a mating part is deliberately made slightly oversize for the part into which it will be inserted.
Interleaving The insertion of paper or application of suitable strippable coatings between layers of metal to protect from damage.
Interlocking Joint A joint in which a curved projection on one part is inserted by a rotating motion into a similarly curved receiving groove on the other part. The parts cannot then be separated by straight-line motion.
Joint Efficiency The strength of a welded joint expressed as a percentage of the strength of the unwelded base metal.
Kerf The notch or slit made by a saw or torch when cutting.
Key-locked Joint A joint with two or more primary elements which are locked together only when an additional specialized part, the key is inserted to prevent them from separating.
Keyway A slot in the shaft of a mechanical drive system that provides a means of locking a gear or other part onto the shaft.
Kink An abrupt deviation from straightness. A kink can be caused by handling.
Lacquer A solution of natural or synthetic resin in an organic solvent with modifying agents, suitable for protective coatings. Lacquers may be clear or colored.
Lambda The Greek letter, corresponding to the letter L, used as a symbol for the coefficient of heat conductivity, the relative rate at which heat is transmitted through a material.
Lamination An internal crack or separation aligned parallel to the extrusion direction, usually caused by contaminants that feed into the metal flow during the forming process or by cracked billets.
Lap Joint A joint formed with one member overlapping the other; the simplest type of nesting joint.
Lapping A method of finishing metal to produce a very smooth, highly accurate surface.
Layout Sample A prototype forging or a cast used to determine conformance to designed dimensions.
Lead-out (equipment context) The initial adjustable and removable section of runout table which is usually stationary (non-activated).
Lead-out (process context) The initial portion of an extruded profile.
Light Walls Undersized wall dimensions often caused by shifting or caving of mandrel or housing section of hollow die.
Lineal Temperature Temperature along the extruded profile's length.
Linearity The extent to which a measuring instrument's response is proportional to the measured quantity.
Line, Flow The line pattern which shows the direction of flow on the surface.
Line, Looper Closely spaced symmetrical lines on the surface of metal which has undergone non-uniform deformation, usually in a drawing operation.
Liner The slab of coating metal that is placed on the core alloy and is subsequently rolled down to clad sheet as composite.
Liquation The bleeding of the low-melting constituents through the solidified ingot surface.
Location A general concept for the typical values or central tendency of a distribution.
Lock A condition in which the parting line of a forging is not all in one plane.
Log The starting stock for extrusion billet. Extrusion log is usually produced in lengths from which shorter extrusion billets are cut.
Long Transverse Direction For plate, sheet and forgings, the direction perpendicular to the longitudinal direction which is also at right angles to the thickness of the product. See also Longitudinal Direction .
Longitudinal Direction The direction of major metal flow in a working operation.
Lot , Heat Treat Material usually of the same mill form, alloy, temper, section and size traceable to one heat-treat furnace load (or extrusion charge or billet in the case of press heat-treated extrusions) or, if heat treated in a continuous furnace, charged consecutively during an 8-hour period.
Lot , Inspection (1) For non-heat treated tempers, an identifiable quantity of material of the same mill form, alloy, temper, section and size submitted for inspection at one time. (2) For heat treated tempers, an identifiable quantity of material of the same mill form, alloy, temper, section and size traceable to a heat treat lot or lots and submitted for inspection at one time. (For sheet and plate, all material of the same thickness is considered to be of the same size.)
Lube, High Lubricant limit exceeds the maximum agreed upon limit measured in weight per unit area.
Lube, Low Failure of the lubricant to meet the agreed upon minimum limit measured in weight per unit area.
Lubricant Any of a number of liquids or semi-solids such as oil, kerosene, grease, lard, fat, soap, tallow and wax used on metal to reduce friction and binding during extruding or forming operations.
Machinability The relative ease of working a metal with machine tools. Aluminum has good machinability.
Machining The quantified removal of metal from the die using a cutting tool or erosion through the electrical discharge process.
Main Cylinder The chamber of an extrusion press into which hydraulic fluid is pumped to generate the desired ram pressure and movement.
Mandrel The fixed or floating projection positioned in the die opening that forces metal to flow around it. The wall thickness of the extrusion is determined by the difference in the dimensions of the die aperture and the mandrel.
Mark Damage in the surface of the product whose name is often described by source.
Mark , Arbor Surface damage in the vicinity of a coil ID caused by contact with a roughened, damaged or non-circular arbor or by the end of the product.
Mark , Bearing A depression in the extruded surface caused by a change in bearing length in the extrusion die.
Mark , Carbon (Graphite) Gray or black surface marking caused by contact with carbon runout blocks.
Mark , Chatter (roll or leveller) Numerous intermittent lines or grooves that are usually full width and perpendicular to the rolling or extrusion direction.
Mark , Handling (1) For rolled products, an area of broken surface that is introduced after processing. The mark usually has no relationship to the rolling direction. (2) For extrusions, damage that can be imparted to the surface during handling operations.
Mark , Rub A large number of very fine scratches or abrasions. A rub mark can occur by metal-to-metal contact, movement in handling and movement in transit.
Mark , Stop A bank-like pattern around the full perimeter of an extruded section and perpendicular to its length. A stop mark occurs whenever the extrusion process is suspended.
Mark , Stretcher Jaw A cross hatched appearance left by jaws at the end(s) of metal that has been stretched. These marks are seen if insufficient metal has been removed after the stretching operation.
Mark , Traffic Abrasion which results from relative movement between contacting metal surfaces during handling and transit. A dark color from the abrasively produced aluminum oxide is usually observed. A mirror image of a traffic mark is observed on the adjacent contacting surface.
Maximum Speed The fastest practical extrusion rate or velocity which is related to the extrusion press ram's velocity. The formula is: Max. ram speed (ipm) x reduction ratio x 12 = maximum speed (ft/min).
Mechanical Properties Those properties of a material that are associated with elastic and inelastic reaction when force is applied, or that involve the relationship between stress and strain; for example, modulus of elasticity, tensile strength, endurance limit. These properties are often incorrectly referred to as physical properties.
Mechanical Working Subjecting metal to pressure exerted by rolls, dies, presses, or hammers to change its form or to affect its structure and its mechanical and physical properties.
Metal Dimension Any dimension, through a part of an extruded cross-sectional shape, whose length includes at least 75 percent metal, versus open space.
Metal Entry The location where the aluminum alloy enters the port opening of a hollow die or the initial opening of a solid die.
Metal Flow The manner in which metal moves both in the container and through the extrusion die.
Mil A unit of length; 0.001 inch.
Mild Steel Steel with a maximum carbon content of about 0.25 percent.
Mill Finish Mill finish is the finish obtained by standard extrusion practices and produced without the aid of any subsequent operations. This finish generally varies from a structural finish with surface imperfections to an architectural finish with uniformly good appearance.
Milling Removing metal with a machine tool something like a rotary chisel.
Mini Insert Die Small self-contained dies that fit into a housing.
Modulus of Elasticity The ratio of stress to corresponding strain throughout the range where they are proportional. As there are three kinds of stresses, so there are three kinds of moduli of elasticity for any material -- modulus in tension, in compression, and in shear.
Multivoting A technique used in the expression of opinions regarding several topics.
Natural Aging See Aging .
Nesting Joints A general class of joints with mating elements that serve to align adjoining parts with little or no self-locking action.
Nitriding The introduction of nitrogen into the surface of tool steels by holding at a suitable temperature in contact with a nitrogenous material, usually ammonia, to produce a hard wear resistant case.
Nitrogen Shrouding The process of injecting nitrogen, either liquid or gaseous, at the die openings to surround the emerging extrusion in an environment high in nitrogen and low in oxygen. This delays the formation of oxides on the exit edge of the die bearing providing a superior surface finish on the extrusion.
Nonferrous Not containing iron; a generic term for metals other than iron and alloys not containing iron.
Nonfill Failure of metal to fill a forging die impression.
Non-Heat Treatable Alloys Aluminum alloys that are strengthened by cold working and not by heat treatment.
Notch Double Shear An abrupt deviation from straight on a sheared edge. This offset may occur if the flat sheet or plate product is longer than the blade for the final shearing operation.
O.D. (Outside Diameter) The nominal overall measurement of tube or pipe diameter measured across its outer perimeter because of variations in actual wall thickness, it does not necessarily indicate true dimensions at all location.
Off Contour The deviation of a cross-section surface otherwise intended to be flat.
Off Gauge Deviation of thickness or diameter of a solid product, or wall thickness of a tubular product, from the standard or specified dimensional tolerances.
Offset-Yield Strength Yield strength by the offset method is computed from a load-strain curve obtained by means of an extensometer. A straight line is drawn parallel to the initial straight line portion of the load-strain curve and at a distance to the right corresponding to 0.2 percent offset (0.002 in. per in. of gauge length). The load reached at the point where this straight line intersects the curve divided by the original cross-sectional area (sq. in.) of the tension test specimen if the yield strength.
Opaque Impervious to the transmission of light. Aluminum is opaque; even a thin aluminum foil completely blocks the transmission of light.
Open Space Dimension A dimension, across a part of an extruded cross-sectional shape which only partially encloses a space, whose length includes more than 25 percent space, versus metal.
Operational Definition A means of clearly communicating quality expectations and performance; it consists of 1) A criterion to be applied to an object or to a group, 2) A test of the object or of the group, 3) A decision: yes or no; the object or the group did or did not meet the criterion.
Orange Peel (1) Surface roughening on formed products which occurs when large grains in the metal are present. (2) An irregularity in the surface of a paint film resulting from the inability of the wet film to level out, or become smooth after being applied, thus resembling the surface of an orange. This finish may be considered desirable or a defect depending on the end use.
Orientation (Laying Out) The placement of die openings for best profile attitude and consequent flow distribution.
Orifice The opening in an extrusion die through which the material is extruded.
Oscillation Uneven wrap in coiling and lateral travel during winding. Improper alignment of rolls over which the metal passes before rewinding and insufficient rewind tension are typical causes. See also Telescoping .
Ovality Deviation from a circular periphery, usually expressed as the total difference found at any one cross section between the individual maximum and minimum diameters, which usually occur at or about 90 degrees to each other. Since ovality is the difference between extreme diameters, it is not expressed as plus or minus.
Overbending Bending metal through a greater angle than that required in the finished part, to compensate for the tendency of the metal to spring part way back to its original shape.
Oxide A chemical compound of oxygen with another element. Hydrated (water-including) iron oxide is called rust; it does not cling tightly to the underlying metal, so the oxidation process is progressive and iron easily rusts away. Aluminum oxide is a hard, transparent compound which clings tightly to the underlying metal and protects it against further oxidation.
PSA Abbreviation for a process known as Pressure Swing Absorption which produces gaseous nitrogen for shrouding in the die area.
PSI (or P.S.I.) Pounds per square inch a measure of pressure or mechanical load.
Pancake Die A three piece hollow die composed of a die, backer and porthole, which shortens the feed length.
Parent Coil A coil that has been processed to final temper as a single unit. The parent coil may subsequently be cut into two or more smaller coils or into individual sheets or plates to provide the required width and length.
Parent Plate A plate that has been processed to final temper as a single unit. The parent plate may subsequently be cut into two or more smaller plates to provide the required width and length.
Parting Line A condition unique to stepped extrusions where more than one cross section exists in the same extruded shape. A stepped shape uses a split die for the minor or small cross section and after its removal another die behind it for the major configuration. Slightly raised fins can appear on that portion of the shape where the two dies meet.
Peen Gun A tool used to hammer the surface of a die.
Pencil Hardness A method of evaluating hardness/adhesion using graded drawing leads, often used as an indication of cure.
Permanent Set The plastic (non-elastic) deformation or deformation above the elastic limit, remaining after the load is removed.
Permeability The passage or diffusion of a gas, vapor, liquid or solid through a barrier without physically altering it; the rate at which this diffusion or passage occurs. Aluminum is essentially impermeable, an important factor in its widespread use in containers and packaging.
Physical Properties The properties, other than mechanical properties, that pertain to the physics of a material; for example, density, electrical conductivity, heat conductivity, thermal expansion.
Piastrina A pocket in the die cap of specified depth and distance from the bearing around the profile's contour before the bearing that allows additional control of the metal flow. Sometimes termed a Forming Pocket.
Pick-Off The transfer of portions of the coating from one surface of the sheet to an adjacent surface due to poor adhesion of the coating.
Pickup Small particles of oxide adhering to the surface of a product at irregular intervals.
Pigment An insoluble coloring agent suspended in a fluid medium, as in inks, lacquers, and paints.
Pigment A dry substanced dispersed uniformly in a paint to give color, opacity, or other special properties.
Pin Core A replaceable mandrel core.
Pin Gauges Precision machined pins used for measuring normally available as plus, minus and net size.
Pin Openings A method commonly used for checking wall thickness consistency in a die using pin gauges.
Pinouts The actual dimensions of a die opening measured with pin gauges.
Pinhole (1) Minute hole in foil. (2) A small-sized void in the coating of a sheet or foil product. A typical cause is solvent popping.
Pipe, Drawn Pipe brought to the final dimensions by drawing through a die.
Pipe, Extruded Pipe formed by hot extruding.
Pipe, Structural Pipe, brought to final dimensions by extruding through a bridge-type die or by similar methods at the option of the producer. (Typically used for structural, nonpressure applications.)
Pit (1) A depression in the rolled surface which is usually not visible from opposite side. (2) A sharp depression in the surface.
Plastic Deformation Distortion that remains after removal of the load that caused it.
Plasticity The ability of a material to be deformed extensively without rupture.
Plastisol A coating incorporating polyvinyl chloride (PVC), used mainly on such products as industrial building sheets and residential siding, and sometimes formulated for spraying. Plastisols require application of a special primer to achieve proper bonding to aluminum.
Plate A rolled product that is rectangular in cross section and with thickness not less than 0.250 inch with sheared or sawed edges.
Plate Circle Circle cut from plate.
Plate, Alclad Composite plate comprised of aluminum alloy core having on both surfaces (if on one side only, Alclad One Side Plate) a metallurgically bonded aluminum or aluminum alloy coating that is anodic to the core, thus electrolytically protecting the core against corrosion.
Platen Pressure Ring A hardened tool steel ring inserted into the platen to support the die and support tools.
Platen Ring Opening The recessed opening in the rear face of the front extrusion press platen into which the pressure ring is inserted to provide support for the tool stack.
Polishing Smoothing a metal surface, usually by rubbing with fine abrasives. A mechanical finishing operation for the purpose of producing a gloss or luster on the surface of a product.
Polymer A chain-like compound of high molecular weight formed by the linkage of simple molecules (monomers) under suitable conditions. When two or more different monomers are involved, the product is called a copolymer.
Pop, Solvent Blister and/or void in the coating resulting from trapped solvents released during curing process.
Porosity Fine pores or hollows within a body of metal.
Port Opening The openings or entry on the face of a porthole die through which the aluminum separates and flows into the welding chamber.
Porthole Die A die having a stationary core or mandrel which is held in place by integral core supports or webs. The porthole die is a modification of the spider die, except that the spider is replaced with a chambered disk that supports the mandrel (sometimes termed a stub mandrel); several portholes running through it annularly about the mandrel, distinguish the porthole types. The die contains a weld chamber so that when the billet is pushed the metal divides to flow around the core supports and welds together in the welding chamber before passing through the die. Porthole dies are used in producing extruded hollow profiles and tubing. See Bridge and Spider Dies .
Ports The feed area on the entry side of a hollow side of a hollow die which are the openings through which the metal stream flows.
Pot The common name for a single electrolytic aluminum reduction cell. See Cell .
Powder Coating Application of a coating in the form of a finely ground powder of coloring agents, resins, and additives; heating of the part, either before or after powder deposition, fuses the powder into a continuous coating.
Prechamber A recessed pocket built into the die cap of a hollow die with the approximate configuration of the die openings. The purpose of this pocket is to aid in correcting for small distortion.
Precision (of measurement) The extent to which repeated measurement of a standard with a given instrument yields the same result.
Preheating A high temperature soaking treatment to provide a desired metallurgical structure. Homogenizing is a form of preheating.
Press Alignment The relationship between the center lines of the container, ram, and tool stack.
Press, Extrusion The hydraulic machine which applies pressure to an aluminum billet inside a container, extruding it through the opening of a die.
Press Tools Parts of an extrusion press that are changed to produce a specific shape. This includes stem, fixed dummy, container and liner.
Pressure Ring A steel ring that is fitted into the center of the press platen against which the tooling stack is supported during extrusion.
Pretreatment The chemical alteration of a surface to make it suitable for application of paint or powder. The process usually includes cleaning and applying a conversion coating.
Primer Type of paint applied to a surface to increase its comptability with a topcoat, or to improve adhesion or the corrosion resistance of the substrate.
Profile A product that is long in relation to its cross-sectional dimensions, having a cross-section other than those of wire, rod, bar, and tube, produced by extrusion, rolling, drawing, or cold finishing. Formerly termed a shape.
Profile, Class 1 Hollow Extruded A hollow extruded profile, the void of which is round and 1 inch or more in diameter and whose weight is equally distributed on opposite sides of two or more equally spaced axes.
Profile, Class 2 Hollow Extruded Any hollow extruded profile other than Class 1, which does not exceed a 5-inch diameter circumscribing circle and has a single void of not less than 0.375-inch diameter or 0.110-square inch area.
Profile, Class 3 Hollow Extruded Any hollow extruded profile other than class 1 or Class 2.
Profile, Cold-Finished A profile brought to final dimensions by cold-working to obtain improved surface finish and dimensional tolerances.
Profile, Cold-Finished Extruded A profile produced by cold-finishing an extruded profile.
Profile, Cold-Finished Extruded A cold-finished section produced from an extruded profile which is brought to final dimensions by cold working to obtain improved surface finish and closer dimensional tolerances.
Profile, Cold-Finished Rolled A profile produced by cold-finishing a rolled profile.
Profile, Drawn A profile brought to final dimensions by drawing through a die.
Profile, Extruded A profile produced by hot extruding.
Profile, Fluted Hollow A hollow profile having plain inside surfaces and whose outside surfaces comprise regular, longitudinal, concave corrugations with sharp cusps between corrugations.
Profile, Helical Extruded An extruded profile twisted along its length. (Sometimes erroneously called spiral ).
Profile, Hollow A profile, any part of whose cross section completely encloses a void.
Profile, Hollow Extruded (Class 1) A hollow extruded profile whose void is round and one inch or more in diameter, and whose weight is equally distributed on opposite sides of two or more equally spaced axes.
Profile, Hollow Extruded (Class 2) Any hollow extruded profile other than Class 1, which does not exceed a 5-inch diameter circumscribing circle and has a single void of not less than 0.375 inch diameter or 0.110 square inch area.
Profile, Hollow Extruded (Class 3) Any hollow extruded profile other than Class 1 or Class 2.
Profile, Lip Hollow A hollow profile of generally circular cross section and nominally uniform wall thickness with one hollow or solid protuberance or lip parallel to the longitudinal axis; used principally for heat-exchange purposes.
Profile, Pinion Hollow A hollow profile with regularly spaced, longitudinal serrations outside and round inside, used primarily for making small gears.
Profile, Rolled A profile produced by hot rolling.
Profile, Semihollow A profile any part of whose cross section is a partially enclosed void the area of which is substantially greater than the square of the width of the gap. The ratio of the area of the void to the square of the gap is dependent on the class of semihollow profile, the alloy and the gap width.
Profile, Semihollow Extruded A semihollow profile brought to final cross-sectional area by extruding.
Profile, Solid A profile other than hollow or semihollow.
Profile, Spiral Erroneously used sometimes where the term helical extruded profile is intended.
Profile, Stepped Extruded An extruded profile whose cross-section changes abruptly in area at intervals along its length.
Profile, Streamline Hollow A hollow profile with a cross-section of teardrop shape.
Profile, Structural A profile in certain standard alloys, tempers, sizes, and section, such as angles, channels, H-sections, I-beams, tees, and zees commonly used for structural purposes. For channels and I-beams, there are two standards, namely Aluminum Association Standard and American Standard.
Profile, Tapered Extruded An extruded profile whose cross section changes continuously in area along its length or a specified portion thereof.
Puller A device which guides metal down the runout table as it is being extruded.
Quench, Air and Water Usually refers to quenching or rapid cooling at the die, where large volumes of forced air, water or a combination thereof are directed against aluminum extruded sections as they emerge from the die.
Quenching Controlled rapid cooling of a metal from an elevated temperature by contact with a liquid, a gas, or a solid.
Radial Layout The method of locating the apertures in a die so that the major axis of each profile lies along a circle of defined radius, giving each portion of bearing surface the same relationship to the center of the die as similar portions on other profiles.
Ram The press component which applies force against the dummy block. Ram and stem are interchangeable terms describing any extension of the main cylinder in an extrusion press.
Reciprocator A mechanical device which moves an applicator along a determined path repeatedly.
Recovery The amount of saleable aluminum in the form of extrusions obtained from a press run. The recovery ratio is the proportion of such saleable metal to either the original ingot or to the ready-to-extrude billet, as the case may be.
Reduction In metallurgy, the electrochemical process by which purified alumina (aluminum oxide) is broken down into its constituents, freeing metallic aluminum.
Reduction Ratio (Extrusion Ratio) The comparison of the cross-sectional billet area to total cross-sectional area of the resulting extrusions. This is determined by the cross-sectional area of the container or upset billet divided by the cross-sectional area of the combined die openings.
Refined Aluminum Aluminum of very high purity (99.950 percent or higher) obtained by special metallurgical treatments.
Reflectivity The ability of a surface to reflect light and other electromagnetic radiation. Aluminum has high reflectivity: 80% or more for visible light, and 90% or more for infrared radiation.
Reheating Heating metal again to hot-working temperature. In general no structural changes are intended.
Relieved Aperture or opening in a die where its entrance is smaller than the exit.
Residual Stresses Those stresses set up within a metal as the result of non-uniform plastic deformation which may be caused by drastic temperature gradients in quenching.
Resilience The ability of a material to regain its original shape after distortion. Aluminum is a resilient material.
Resolution (of a measuring instrument) The smallest unit of measure that an instrument is capable of accurately and repeatedly indicating.
Restrictor Bumps (dams, speed bumps) A bulge or hump in the die's metal flow area serving as a means of controlling the flow or feed of metal.
Rib An elongated projection on a shape, forging or casting to provide stiffening.
Ring Tooling (die ring) A cylindrical sleeve that holds the die and backer in axial relationship to each other.
Rivet (1) To connect two or more pieces of material by inserting in a hole through them a metal pin with a head on one end of it, and then forming a second head on the other end; (2) The connecting pin itself.
Rockwell Hardness See Hardness, Rockwell .
Rod A solid wrought product, long in relation to its cross-section, which is not less than 0.375 inch in diameter. (Smaller sizes are classified as wire.)
Rod, Alclad Rod having on its surface a metallurgically bonded aluminum or aluminum alloy coating that is anodic to the core alloy to which it is bonded, thus electrolytically protecting the core alloy against corrosion.
Rod, Extruded Rod produced by hot extruding.
Rod, Rolled Rod produced by hot rolling.
Rod Runout Length The length of extrusion rod from each billet.
Roundness This term is not recommended. The term Ovality is preferred.
Rub, Tool A surface area showing a scratch or abrasion resulting from contact of the hot extrusion with the press equipment or tooling or, in the case of multi-hole dies, with others sections as they exit the press.
Run, Statistics A consecutive number of points consistently increasing or decreasing, or above or below the central line. Can be evidence of the existence of special causes of variation.
Runout Table Table at immediate exit of press leadout equipment which helps to guide and support the extrusion.
Sag Downward flow of a paint film as a result of its being applied too heavily or too wet. Also called Runs.
Salt Spray Corrosion test using salt sprayed as a mist in a heated humidity chamber to simulate seashore conditions, or to accelerate corrosion at a controlled rate.
Sandwiching The simultaneous extrusion of two layers of metal failing to weld because of film impurities between them.
Scalping Mechanical removal of the surface layer from a fabricating ingot or semi-finished wrought product so that surface imperfections will not be worked into the finished product.
Screw Index A provision on some extrusion presses for moving the die in a horizontal plane with respect to the container.
Screw Boss The part of the die or mandrel bearing used to make screw holes in the extrusion.
Sealing Pressure The pressure which locks the container and die face during the extrusion cycle.
Seam The junction line of metal that has passed through a hollow die, separated and rejoined at the exit point. Seams are present in all extruded hollows produced from the extrusion process and in many cases are not visible.
Seam Defect An unbonded fold or lap on the surface of the metal, which appears as a crack, usually the result of a defect in casting or working that has not bonded shut.
Seam, Extrusion See Seam, Weld .
Seam, Weld The junction line of metal that has passed through a hollow die, separated and rejoined at the exit point. Seams are present in all extruded hollows produced from the direct extrusion process and in many cases are not visible.
Seamless A hollow product which does not contain any line junctures resulting from method of manufacture.
Secondary Aluminum Aluminum recovered primarily from scrap, segregated by alloy, and resmelted. Aluminum scrap is widely recycled and supports a large secondary aluminum production industry.
Section (1) A drawing showing an imaginary view through an item as though it had been cut by a plane (2) To cut through a piece of metal to expose an internal area for metallurgical examination.
Section Number The number assigned to an extruded or drawn profile for identification and cataloging purposes, usually the same number assigned for the same purpose to the die from which the profile is made.
Section Print An engineering drawing depicting the extrusion profile's cross-section.
Self-tapping Screw A hardened screw with a sharp point, so designed that its threads cut their own mating threads when inserted and rotated in an appropriately-sized hole.
Semihollow Profile An extruded profile, any part of whose cross section partially encloses a void, the area of which is substantially greater than the square of the width of the gap.
Shadow Surface discoloration.
Shear Bridge Die A bridge die that is recessed in a ring so that the butt can be sheared without any die stripping.
Shear, Butt The device which separates or removes the extrusion residue or discard (billet butt) at the end of each cycle.
Shear Edge The leading (entry side) edge of a mandrel or die cap bearing.
Shear Edge Shifted A condition where the mandrel shear edge is offset from the die cap bearing edge.
Shear Strength The maximum stress that a material is capable of sustaining in shear. In practice, shear strength is considered to be the maximum average stress computed by dividing the ultimate load in the plane of shear by the original area subject to shear. Shear strength is usually determined by inserting a cylindrical specimen through round holes in three hardened steel blocks, the center of which is pulled (or pushed) between the other two so as to shear the specimen on two planes. The maximum load divided by the combined cross-sectional area of the two planes is the shear strength.
Sheet A rolled product that is rectangular in cross section with thickness less than 0.250 inch but not less than 0.006 inch and with slit, sheared or sawed edges.
Sheet Stock See Reroll, Stock .
Sheet, Alclad Composite sheet comprised of an aluminum alloy core having on both surfaces (if one side only, Alclad One Side Sheet) a metallurgically bonded aluminum or aluminum alloy coating that is anodic to the core, thus electrolytically protecting the core against corrosion.
Sheet, Anodizing Sheet with metallurgical characteristics and surface quality suitable for the development of protective and decorative films by anodic oxidation processes.
Sheet, Clad Composite sheet having on both surfaces (if on one side only, Clad One Side Sheet) a metallurgically bonded metal coating, the composition of which may or may not be the same as that of the core.
Sheet, Coiled Sheet in coils with slit edges.
Sheet, Coiled Circles Circles cut from coiled sheet.
Sheet, Coiled Cut to Length Sheet cut to specified length from coils and which has a lesser degree of flatness than flat sheet.
Sheet, Flat Sheet with sheared, slit, or sawed edges, which has been flattened or leveled.
Sheet, Flat Circles Circles cut from flat sheet.
Sheet, Mill Finish (MF) Sheet having a non-uniform finish that may vary from sheet to sheet and within a sheet, and may not be entirely free from stains or oil.
Sheet, One Side Bright Mill Finish (1SBMF) Sheet having a moderate degree of brightness on one side and a mill finish on the other.
Sheet, Painted Sheet, one or both sides of which has a factory-applied paint coating of controlled thickness.
Sheet, Standard One Side Bright Finish (S1SBF) Sheet having a uniform bright finish on one side and a mill finish on the other.
Sheet, Standard Two Sides Bright Finish (S2SBF) Sheet having a uniform bright finish on both sides.
Shifting Walls Uneven walls caused by core (mandrel) movement.
Short Choke A condition in an extrusion die where a very slight chamfer is created on the edge formed by the bearing surface and die face which is much shorter than regular choke. This tends to slow metal flow.
Short Transverse Direction For plate, sheet and forgings, the direction through the thickness perpendicular to both longitudinal and long transverse directions.
Shrinkage Contraction that occurs when metal cools from the hot-working temperature.
Shut Off/Seal Off Semihollow Die A semihollow die where the die plate (cap) and the mandrel overlap each other at or near the tongue. The interior profile surface is formed by the mandrel and the outside surface by the die cap. The two tooling components mate together with an overlapping condition to crate the semihollow profile.
Side Set A difference in thickness between the two edges of plate, sheet or foil.
Skewed A nonsymmetric distribution is said to be skewed.
Skip An area of uncoated sheet which is frequently caused by equipment malfunction.
Skull A residual buildup of aluminum alloy from preceding billets that adhere to the container liner wall. The thickness is determined by difference in container I.D. and circumference of dummy block. See Cleanout Block.
Slip-fit Joint A joint assembled by sliding two mating parts together in the direction of their length.
Sliver Thin fragment of aluminum which is part of the material but only partially attached. Surface damage or residual liquation which is subsequently rolled are typical causes.
Slug A metal blank for forging or impacting.
Smudge A dark film of debris, sometimes covering large areas, deposited on the sheet during rolling.
Snap-fit Joint A self-locking joint whose mating parts exert a cam action, flexing until one part slips past a raised lip on the other part, preventing their separation.
Snap Ring A mark or blemish left on the surface of the extrusion caused by any sudden die or extrusion tooling movement.
Soaking In metallurgy: the prolonged heating period during several methods of heat treating metals, soaking allows the heat to penetrate completely the mass of metal, and so permits the required metallurgical changes to take place.
Soft Alloy A general term loosely describing most alloys of the 1xxx, 3xxx, or 6xxx series.
Soldering Joining metals by flowing a molten filler metal between the connecting surfaces at a melting range below an arbitrary temperature, usually about 800 º F. (At higher temperatures, the process is call brazing.) The filler metal, called solder, may have any of a variety of compositions formulated for the different metals to be joined; the so-called soft, or low-melting, solders are primarily of tin and lead.
Solid Dies A steel disk with one or more orifices or apertures of the same cross-sectional area and contour as the desired product, through which metal is forced. Such dies are generally employed where profiles other than hollow are required. If solid dies are used for hollow profiles (as opposed to the use of hollow dies of the bridge, porthole or spider type containing a fixed stub mandrel as an integral part of the die) then a mandrel actuated by the action of the ram must be employed. These may be fixed or floating mandrels which require hollow (cast or bored) billets. An exception is the piercing type mandrel, which needs no cored billet.
Solid Profile Any profile other than a hollow or semihollow.
Solution Heat Treating Heating an alloy at a suitable temperature for sufficient time to allow soluble constituents to enter into solid solution where they are retained in a supersaturated state after quenching.
Solvent Pop Blistering caused by entrapped solvent during baking, possibly caused by short flashoff or improper solvent balance.
Solvent Resistance The ability of cured paint film to resist attack by a particular solvent. Often used as an indication of cure.
Specification The engineering requirement for judging acceptability of a particular characteristic. A specification is never to be confused with a control limit.
Specimen That portion of a sample taken for evaluation of some specific characteristic or property.
Speed, Bearing Is a reduction in the effective bearing length and is the opposite correction technique to choke. See Relieved, Back Taper.
Speed Tear A series of surface cracks perpendicular to the extruding direction. Speed tearing normally occurs in corner radii or extremities of a section and is caused by localized high temperature.
Spider Die An extrusion die for producing hollow shapes, whose mandrel is supported by multiple legs attached to the cap. Metal flows between the spider's legs and reunites before emerging through the die aperture.
Splice The end joint uniting two webs.
Spot, Lube A non-uniform extraneous deposit of lube on the coated sheet.
Spreader An auxiliary tool sometimes attached to the end of the container to produce an effective billet of greater size than the I.D. of the container. Use of a spreader permits the extruding of sections considerably wider than container I.D., but only under definitely limited operating conditions.
Square Bearing A bearing surface exactly perpendicular to the die face and ideally to the metal flow.
Squareness (1) The measure of a bearing being perpendicular to the die face which can be accomplished with a toolmaker's square or equivalent techniques. (2) Characteristic of having adjacent sides or planes meeting at 90 degrees.
Stabilizing A low temperature thermal treatment designed to prevent age-softening in certain strain hardened alloys containing magnesium.
Stain, Heat Treat A discoloration due to non-uniform oxidation of the metal surface during heat treatment.
Stain, Oil Surface discoloration which may vary from dark brown to white and is produced during thermal treatment by incomplete evaporation and/or oxidation of lubricants on the surface.
Stain, Saw Lubricant A yellow to brown area of surface discoloration at the ends of the extruded length. It is the residue of certain types of saw lubricants if they are not removed from the metal prior to the thermal treatment.
Stain, Water See Corrosion, Water Stain .
Standard An established dimensional tolerance for a certain class of product.
Starvation Non-uniform coating application which results in absence of coating in certain areas.
Starving Wall Light walls on the extruded profile caused by a restricted flow of metal before the bearing entry.
Stepped Extrusion An extrusion having one or more abrupt changes in cross section at intervals in its length.
Stepped Extrusion Process A process similar to the conventional extrusion process producing an extrusion with abrupt changes in dimension. In this process the extrusion press is stopped when the billet is only partially extruded, the split dies are removed and replaced with dies of larger opening or orifice. Extrusion is then resumed. The result is an extrusion which has an abrupt change in cross section. The first portion extruded having the smaller cross section is called the minor section while the second portion having the larger cross section is called the major section.
Sticking Adherence of foil surfaces sufficient to interfere with the normal ease of unwinding.
Straightness The absence of divergence from a right (straight) line in the direction of measurement.
Strain A measure of the change in size or shape of a body under stress, referred to its original size or shape. Tensile or compressive strain is the change, due to force, per unity of length in an original linear dimension in the direction of the force. It is usually measured as the change (in inches) per inch of length.
Strain Hardening Modification of a metal structure by cold working, resulting in an increase in strength and hardness with loss of ductility.
Streak (Stripe) A superficial band or elongated mark which produces a non-uniform surface appearance. A streak is often described by source.
Streak, Bearing A longitudinal discoloration that can occur where there are large changes in wall thickness as a result of uneven cooling. These streaks usually appear lighter than the surrounding metal.
Streak, Bright A bright superficial band or elongated mark which produces a non-uniform surface appearance.
Streak, Buff A dull continuous streak caused by smudge buildup on a buff used at shearing or other operations.
Streak, Burnish A bright region on the sheet caused by excessive roll surface wear.
Streak, Coating A banded condition caused by non-uniform adherence of roll coating to a work roll. It can be created during hot and/or cold rolling. If generated in the hot rolling process, it is also called Hot Mill Pick-up.
Streak, Diffusion Surface discoloration which may vary from gray to brown and found only on Alclad products.
Streak, Dirt Surface discoloration which may vary from gray to black, is parallel to the direction of rolling, and contains rolled in foreign debris. It is usually extraneous material from an overhead location that drops onto the rolling surface and is shallow enough to be removed by etching or buffing.
Streak, Grease A narrow discontinuous streak caused by rolling over an area containing grossly excessive lubricant drippage.
Streak, Grinding A streak with a helical pattern appearance transferred to a rolled product from a work roll.
Streak, Heat Milky colored band(s) parallel to the rolling direction which vary in both width and exact location along the length.
Streak, Herringbone Elongated alternately bright and dull chevron markings.
Streak, Leveller A streak on the sheet surface in the rolling direction caused by transfer from the leveler rolls.
Streak, Roll A non-uniform surface appearance parallel to the rolling direction.
Streak, Structural A non-uniform appearance on an etched or anodized surface caused by heterogeneities (variabilities) remaining in the metal from the casting, thermal processes or hot working stages of fabrication.
Strength/Weight Ratio The relationship between the structural strength of a material and its weight. the strength-to-weight ratio of structural aluminum alloys is about twice that of mild steel.
Stress Force per unit of area. Stress is normally calculated on the basis of the original cross-sectional dimensions. The three kinds of stresses are tensile, compressive, and shear.
Stress Relieving The reduction of the effects of internal residual stresses by thermal or mechanical means.
Stretch Straightening The process of stretching extruded sections beyond the yield strength of the alloy to achieve longitudinal straightness.
Stretcher Flattening A process of removing bow and warpage where an extrusion is gripped between jaws and subjected to a stress higher than its yield strength and is elongated a definite amount to establish a permanent set.
Stretching In extrusion: straightening an aluminum member by pulling. An average stretch increases the length by about one-half of one percent, and produces correspondingly a slight decrease in the cross-sectional dimensions, called stretch-down.
Striation Longitudinal non-uniform coating thickness caused by uneven application of the liquid coating.
Structural Finish A structural finish is a standard finish where surface imperfections are acceptable and appearance is not a requirement. This finish could be characterized by the term non-exposed.
Structural Shape An aluminum section, now usually extruded, of any design accepted as standard by the structural industry. Such shapes include I-beams, wide flange or H-beams, channels, angles, tees and zees.
Sub-Bolster A hardened alloy steel disk often employed when the bolster does not fill the die stack. See Bolster .
Substrate The Layer below the paint; that is, the substance being painted.
Suck-In A defect caused when one face of a forging is sucked in to fill a projection on the opposite side.
Surface Tear Minute surface cracks on rolled products which can be caused by insufficient ingot scalping.
Taper Heating A staged or gradient heating.
Taper Seal Die A type of hollow die using a taper or conical angle to seal the die and its ring.
Tear, Speed A series of surface cracks perpendicular to the extruding direction. Speed tearing normally occurs in corner radii or extremities of a section and is caused by localized high temperature.
Tearing Typically cracks or separations due to high extrusion speed or extrusion temperature.
Telescoping Lateral stacking, primarily in one direction, of wraps in a coil so that the edges of the coil are conical rather than flat. Improper alignment of rolls over which the metal passes before rewinding is a typical cause. See also Oscillation.
Temper The combination of hardness and strength imparted to a metal by mechanical or thermal treatments and characterized by certain metallurgical structures and mechanical properties determining temper designation.
Tensile Strength In tensile testing, the ratio of maximum load to original cross-sectional area. Also called Ultimate Strength.
Thermal Conductivity The ability of a material to transmit heat through its bulk and, by direct contact, to other substances. Aluminum is a good heat conductor and is widely used in cookware and in radiators and other heat exchangers.
Tolerance Allowable deviation from a nominal or specified dimension.
Tongue That portion of die cap metal surrounded by the aperture except at one end which is termed the base of the tongue.
Tongue (of an extrusion die) An area of a die surrounded on three sides by the extrusion aperture.
Tongue Cave Distortion of the die tongue.
Tongue and Groove Joint A joint in which one part has a groove which receives a projection (tongue) on the other part, shaped to fit snugly.
Tonnage Press hydraulic pressure times cylinder area, expressed in U.S. tons.
Tool A term usually referring to the dies, mandrels, etc., used in the production of extruded or drawn profiles or tube.
Tools or Tooling The parts of an extrusion press that are changed to produce a specific shape. Tools include dies and mandrels, and various supporting parts.
Tool Deflection See Deflection . The distortion, displacement or caving in the extrusion direction of the extrusion die or tool surface under extrusion pressure.
Tool Rub A surface area showing a scratch or abrasion resulting from contact of the hot extrusion with the press equipment or tooling or, in the case of multi-hole dies, with other sections as they exit the press.
Tooling Plate A cast or rolled product of rectangular cross section of thickness 0.250 inch or greater, and with edges either as-cast, sheared or sawed, with internal stress levels controlled to achieve maximum stability for machining purposes in tool and jig applications.
Topcoat In a multi-coat system, the coat applied over a primer, usually the final coat applied.
Torn Surface A deep longitudinal rub mark resulting from abrasion by extrusion or drawing tools.
Toxicity The degree to which a substance is toxic, or poisonousness.
Traffic Mark Abrasion which results from relative movement between contacting metal surfaces during handling and transit. A dark color from the abrasively produced aluminum oxide is usually observed. A mirror image of a traffic mark is observed on the adjacent contacting surface.
Transverse Direction A direction perpendicular to the direction of working.
Transverse Weld A condition existing within an extrusion which is created by the interface of two separate billets. In practice the interface is extruded at different rates through the die and is formed into a conical or pointed configuration within a portion of the extrusion.
Tread Plate Sheet or plate having a raised figured pattern on one surface to provide improved traction.
Trend A gradual, systematic change with time or other variables.
Trim Inclusion Edge trimming accidentally wound into a roll of foil.
Tube A hollow wrought product that is long in relation to its cross section, which is symmetrical and is round, a regular hexagon or octagon, elliptical, or square or rectangular with sharp or rounded corners, and that has uniform wall thickness except as affected by corner radii.
Tube Bloom This term is not recommended. The term Tube Stock is preferred.
Tube Stock A semi-finished tube suitable for the production of drawn tube.
Tube, Butt-Welded A welded tube, the seam of which is formed by positioning one edge of the sheet against the other for welding.
Tube, Drawn A tube brought to final dimensions by drawing through a die.
Tube, Embossed A tube the outside surface of which has been roll-embossed with a design in relief regularly repeated in a longitudinal direction.
Tube, Extruded A tube formed by hot extruding.
Tube, Finned Tube which has integral fins or projects protruding from its outside surface.
Tube, Fluted A tube of nominally uniform wall thickness having regular, longitudinal, concave corrugations with sharp cusps between corrugations.
Tube, Heat-Exchanger A tube for use in apparatus in which fluid inside the tube will be heated or cooled by fluid outside the tube. The term usually is not applied to coiled tube or to tubes for use in refrigerators or radiators.
Tube, Helical-Welded A welded tube produced by winding the sheet to form a closed helix and joining the edges of the seam by welding.
Tube, Lap-Welded A welded tube the seam of which is formed by longitudinally lapping the edges of the sheet for welding.
Tube, Redraw This term is not recommended. The term Tube Stock is preferred.
Tube, Seamless Tube that does not contain any line junctures (metallurgical welds) resulting from the method of manufacture. This product may be produced by die-and-mandrel or by hot-piercer processes. Tube produced by porthole-die extrusion, bridge-die extrusion, or welding processes is generally not considered Seamless. (Seamless tube is typically used for fluid-carrying applications under pressure.)
Tube, Sized A tube that, after extrusion, has been cold drawn a slight amount to minimize ovality.
Tube, Stepped Drawn A drawn tube whose cross section changes abruptly in area at intervals along its length.
Tube, Structural Tube commonly used for structural purposes.
Tube, Welded A tube produced by forming and seam-welding sheet longitudinally.
Tubing, Electrical Metallic A tube having certain standardized length and combinations of outside diameter and wall thickness thinner than that of Rigid Conduit , commonly designated by nominal electrical trade sizes, for use with compression-type fittings as a protection for electric wiring.
Tubing Product A general term comprising tube, hollow profiles, and semi-hollow profiles.
Tubular Conductor A tubular product suitable for use as an electric conductor.
Twist (1) For rolled products, a winding departure from flatness. (2) For extrusions, a winding departure from straightness.
Two-Tone A sharp color demarcation in the appearance of the metal due to a difference in the work roll coating.
Ultraviolet Electromagnetic radiation at wavelengths shorter than violet light and just beyond the visible light spectrum. Sunlight includes ultraviolet radiation, which causes tanning or sunburn in human skin and which may cause chemical or structural changes in some commercial materials. Aluminum reflects ultraviolet radiation and is not damaged by it.
Unbalanced Feed Is insufficient metal in one or more locations within the die aperture and is the result of a situation where hollow die ports or flow plate openings do not permit uniform metal flow to all areas of the extrusion die.
Undercure The result of curing a paint at either too low of a temperature or too little time, resulting in inadequate hardness and solvent resistance.
V.O.C. Volatile organic compound; any organic compound that participates in atmospheric photochemical reactions as designated by EPA standards.
Vapor barrier A material which prevents or impedes the passage of water vapor through the walls of a structure or container. Aluminum is an excellent vapor barrier.
Vent The action of relieving entrapped air or gases by a venting or burp procedure during the extrusion process.
Vent Mark A small protrusion on a forging resulting from the entrance of metal into a die vent hole.
Viscosity That property of a liquid which enables it to resist flow. High viscosity means a fluid resists flowing; low viscosity means it flows readily.
Void An empty space. In extrusion, the number, sizes, positions, and forms or voids within a hollow shape influence the difficulty of production and the dimensional tolerances which can be assured.
Waving A ripple effect, usually in the leg or legs of an extrusion, caused primarily by either an excessive deflection in the tooling, excessive heat or unbalanced feed.
Web (1) A single thickness of foil as it leaves the rolling mill. (2) A connecting element between ribs, flanges, or bosses on shapes and forgings.
Webs The supporting members of a hollow die mandrel that support the internal surface forming portion of the die.
Weld To join two pieces of metal by applying heat or pressure, causing them to melt in the welded area, mingle and resolidify, forming a single piece.
Weld Chamber The space directly between the web of the mandrel and the die plate, designed to facilitate welding of the billet back together before it is extruded through the die aperture or opening.
Weld Line A region in extruded hollow profiles observed after creating the two streams of metal within the die and rejoining them around the web of a porthole or bridge die. Weld lines may appear as a narrow, dark line.
Weld, Incomplete The junction line of metal that has passed through a die forming a hollow profile (shape), separated and not completely rejoined. Flare testing is a method of evaluating weld integrity.
Welding Joining two or more pieces of aluminum by applying heat or pressure, or both, with or without filler metal to produce a localized union through fusion or recrystallization across the interface. (In cold welding, it is a solid state welding process in which pressure is used at room temperature to produce coalescence of metals with substantial deformation at the weld.)
Welding Rod A rolled, extruded, or cast round filler metal for use in joining by welding.
Welding Wire Wire for use as filler metal in joining by welding.
Wettability Test The degree to which a metal surface may be wet to determine the absence of or the amount of residual rolling or added lubricants or deposits on the surface.
Wire A solid wrought product that is long in relation to its cross section, which is square or rectangular with sharp or rounded corners or edges, or is round, hexagonal, or octagonal, and whose diameter or greatest perpendicular distance between parallel faces is less than 0.375 inch.
Wire, Alclad A composite wire product comprised of an aluminum-alloy wire having on its surface a metallurgically bonded aluminum or aluminum-alloy coating that is anodic to the alloy to which it is bonded, thus electrolytically protecting the core alloy against corrosion.
Wire, Cold-Heading Wire of quality suitable for use in the manufacture of cold-headed products such as rivets and bolts.
Wire, Drawn Wire brought to final dimensions by drawing through a die.
Wire EDM Is an electrical discharge machining except that a wire is used as the electrode and the dielectric is frequently ionized water. These machines are numerically controlled and computer programmed.
Wire, Extruded Wire produced by hot extruding.
Wire, Flattened Wire having two parallel flat surfaces and rounded edges produced by roll-flattening round wire.
Wire, Flattened and Slit Flattened wire that has been slit to obtain square edges.
Workability The relative ease with which various alloys may be formed by extruding, rolling, forging, etc.
Wrap A characteristic of liquid or powder coatings in an electrostatic application to seek out and adhere to parts of the substrate not in direct line of sight of the delivery system end point.
Wrap, Loose A condition in a coil due to insufficient tension which creates a small void between adjacent wraps.
Wrought Product A product that has been subjected to mechanical working by extruding, rolling, forging or other processes.
Yield Strength The stress at which a material exhibits a specified permanent set. The offset used for aluminum and its alloys is 0.2 percent of gauge length. For aluminum alloys the yield strengths in tension and compression are approximately equal.