Common Terms in Aluminium
material that has metallic properties and which is composed
of at least two chemical elements, one always being metal. The alloy's properties are usually different from
those of the components.
to subject to high heat, with subsequent cooling so as to
soften and render the product less brittle.
any treatment at elevated temperature which has for its principal
purpose softening and removal of residual stresses. Often, in wrought aluminium products, "annealing" generally
connotes a treatment above the re-crystallisation temperature.
the opening or openings in the die tool, of the same
cross-sectional area and contour as the product to be extruded.
a solid section that is long in relation to its
cross-sectional dimensions, having a symmetrical cross-section that is square or rectangular with sharp or
rounded corners or edges, of is a regular hexagon or octagon, and whose width or greatest distance between
parallel faces 3/8" or greater.
a solid semi-finished round, square or rectangular cast bar
produced in different diameters, sizes and lengths for use in the aluminium extrusion process. Billets may be
cast to diameter and length (book mould) or cast in logs and cut to length (direct chill). Billets may be
solid or hollow (longitudinal hole through centre) and are used in the as-cast or homogenized condition,
depending upon end use and alloy.
usually formed by the step where the die relief starts and
bearing surface ends; also where extrusion leaves bearing.
the un-extruded portion of the billet remaining in the
container after the extrusion cycle is completed. The butt varies in thickness depending upon the billet
condition. The butt is sometimes also called heel.
mechanical deformation of metal or alloy at temperatures below
those at which re-crystallisation occurs. Cold working aluminium can give increased hardness and improved strength.
Cold worked metal may be brought back to the original state of workability by proper
The distortion or bending of the die. Insufficient support of die
will cause it to deflect, lessening the effectiveness of the bearing.
The unit of press tooling with one or more machined
openings to product the desired extruded section or sections.
The surface of extrusion die facing the
reducing wall thickness and outside diameter of tubing. It
is a cold working process in which an extruded tube bloom is elongated by being pulled through a tapered die
or series of tapered dies. A mandrel determines the inside diameter (see sinking).
Conductivity is the capacity of a material to
conduct or allow the flow of an electric current. Conductivity values for aluminium are expressed as percentages of
the conductivity of the International Annealed Copper Standard, which, as indicated below, has a resistive property
of 10.371 ohms per mil foot (a wire 0.001" in dia. and 1' long) at 20° C (68 F).
Properties is the electrical resistance of a body
of unit length and unit cross-sectional area. The value of 10.371 ohms (mil, foot) at 20° C (68F) is the resistive
property equivalent to the International Annealed Copper Standard (IACS) for 100 per cent conductivity, 1 foot in
length and 1 circular mil in cross-sectional area, would have a resistance of 10.371 ohms.
The linear stretch of material during tensile loading. The
increase in distance between two gage marks that results from stressing the specimen in tension or fracture.
Original gage length is usually 2" for sheet specimens and round specimens whose diameter is 1/2", or four times
the diameter for specimens where that dimension under 1/2". Elongation values depend to some extent upon size and
form of the test specimen.
the application of an etching agent to change the metal
conversion of a billet into lengths of uniform cross-section by
forcing metal through or die orifice of the desired cross-sectional outline.
the method of extruding wherein the die and ram are at opposite
ends of the billet. The product and ram travel in the same direction.
the method of extruding where the die is at the ram end of the
billet and the product travels through the hollow ram in the opposite direction.
that level of force employed to cause cast billet to flow through
the auxiliary equipment required to produce extrusions, which is
not an integral or fixed part of the extrusion press. Tools consist principally of container, dummy blocks,
replaceable stems, etc.
the rate at which an extrusion exits from the die; this is
usually expressed as metres per minute.
usually secondary operations applied to extrusions to improve
product dimensionally or change surface condition or colour.
Elasticity is the ratio of stress to corresponding
strain throughout the range where they are proportional. As there are three kinds of
those stresses set up within a metal as the result of non-uniform
plastic deformation which may sometimes be caused by drastic temperature gradients in
the contraction of the extrusion due to such factors as cooling;
the term is also sometimes used for actual thinning by die deflection.
similar to plug drawing except that no inside mandrel or
plug is used. Wall thickness is not altered substantially in a sink pass.
Treatment a process in which an aluminium alloy is
heated to a suitable temperature, is held at the temperature long enough to allow certain constituents to enter
into solid solution and is then cooled rapidly to hold the constituents in solution.
an extrusion having one or more abrupt changes in cross section
at intervals in its length during production.
Process a process similar to the conventional
extrusion process; however, the extrusion press is stopped when the billet is only partially extruded, and the
split dies are removed and replaced with dies of larger opening or orifice.
The superficial etching of the surface from prolonged contact
with moisture in restricted air space. Such stains are usually white or gray in appearance. This condition can find
its water source from either condensation or wetting.