The relative ease of working a metal with machine tools. Aluminum has good machinability.

The quantified removal of metal from the die using a cutting tool or erosion through the electrical discharge process.

The chamber of an extrusion press into which hydraulic fluid is pumped to generate the desired ram pressure and movement.

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.

Damage in the surface of the product whose name is often described by source.

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.

A depression in the extruded surface caused by a change in bearing length in the extrusion die.

A line which is generally perpendicular to the rolling direction.

Defective surface about one inch long, crimped wire shaped and oriented in any direction.

Gray or black surface marking caused by contact with carbon runout blocks.

Numerous intermittent lines or grooves that are usually full width and perpendicular to the rolling or extrusion direction.

Faint intermittent marks at the edge of a cold rolled product which are usually perpendicular to the rolling direction. This mark is caused by action of devices designed to rewind coils without weave.

(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.

Brownish, iridescent, irregularly shaped stain with a slight abrasion located somewhere within the boundary of the stain. It is a result of metal-to-metal contact during the quenching of solution heat-treated flat sheet or plate.

Appearance of surface where actual inclusion or the void it left is observed. See also Inclusion, Stringer.

A continuous scratch (which may also be creased) near a slit edge, caused by sheet contacting the slitter knife.

A small solid protrusion or circular fin on a forging or a casting, resulting from the depression of a knock-out pin under pressure or inflow of metal between the knock-out pin and the die or mold.

Narrow continuous line near the rolled edge caused by a contacting micrometer.

(1) For rolled products, a small repeating raised or depressed area caused by the opposite condition on a roll. The repeat distance is a function of the offending roll diameter. (2) For extrusions, a longitudinal groove or indentation caused by pressure from contour rolls as a profile (shape) passes through them for dimensional correction.

A greatly enlarged roll mark whose height or depth is very shallow. See also Mark, Roll.

A full width line perpendicular to the rolling direction and repeating as a function of a work roll diameter.

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.

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.

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.

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.

A surface abrasion which is generally diagonal to the rolling direction. It is caused by a fluttering action of the metal as it enters the rolling mill.

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).

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.

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.

Any dimension, through a part of an extruded cross-sectional shape, whose length includes at least 75 percent metal, versus open space.

The location where the aluminum alloy enters the port opening of a hollow die or the initial opening of a solid die.

The manner in which metal moves both in the container and through the extrusion die.

Narrow continuous line near the rolled edge caused by a contacting micrometer.

A unit of length; 0.001 inch.

Steel with a maximum carbon content of about 0.25 percent.

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.

Removing metal with a machine tool something like a rotary chisel.

Small self-contained dies that fit into a housing.

The term applied to products, usually flat rolled, which have been processed to minimize internal stress of the kind that causes distortion when material is disproportionately removed from one of the two surfaces through mechanical or chemical means.

Error in register between two halves of a forging or casting by opposing die or mold halves not being in perfect alignment.

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.

Non-uniform surface appearance resulting from uneven pressure distribution between adjacent layers of the product.

Measurement of bursting strength of foil in pounds per square inch. Testing machine applies increasing pressure to one square inch of the sample until it ruptures.

A technique used in the expression of opinions regarding several topics.

See Aging.

A general class of joints with mating elements that serve to align adjoining parts with little or no self-locking action.

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.

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.

Not containing iron; a generic term for metals other than iron and alloys not containing iron.

Failure of metal to fill a forging die impression.

Aluminum alloys that are strengthened by cold working and not by heat treatment.

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.

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.

The deviation of a cross-section surface otherwise intended to be flat.

Deviation of thickness or diameter of a solid product, or wall thickness of a tubular product, from the standard or specified dimensional tolerances.

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.

Impervious to the transmission of light. Aluminum is opaque; even a thin aluminum foil completely blocks the transmission of light.

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.

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.

(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.

The placement of die openings for best profile attitude and consequent flow distribution.

The opening in an extrusion die through which the material is extruded.

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.

An embosses pattern distortion due to misalignment of the male and female embossing rolls.

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.

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.

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.