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Extrusion Terminology

Standard shape Extrusions available to all customers.
Exclusive shape Extrusions manufactured to client design and produced for their exclusive use. These are not published in our catalogue.
Standard Alloys, tempers, dimensions and services always available and acceptable without further reference.
Non-standard Alloys, tempers, dimensions and services which are outside normal availability and always the subject of special inquiry.
Section drawings Profile outline drawings prepared for every extruded shape. Each one is identified by a die number (e.g. UA 1234)
Visible Face In a finished construction, the visible surface of any extrusion.
External periphery The measurement used in computing the price for surface finishes on hollow shapes in which the external perimeter only is measured, and the internal void excluded.
Total periphery The total distance around the extruded shape, including internal void surfaces.
Factor Result of dividing the total perimeter (internal and external for hollow shapes) of the section in millimetres by weight in kg/m.
Circumscribing circle Minimum circle inside which the extruded shapes fit precisely.
Thickness ratio Optimum desirable ratio of variation of metal thickness in any extruded shape.
Rod Solid round section, 10 mm or greater in diameter whose length is great in relation to its diameter.
Bar Solid section, long in relation to its cross-sectional dimensions, with a symmetrical square, rectangular, hexagonal, or octagonal cross-section (excluding flattened wire) with sharp or rounded corners or edges and whose width or greatest distance between parallel faces is 10 mm or greater.
Solid Shape Extruded shape whose geometry does not form a void and which is long in relation to its cross-sectional dimensions.
Hollow Shape Single enclosed void with a width to depth ratio of not less than 5:1. Wall thickness should be uniform except for radiused corners.
Semi-hollow Shape Solid shape with a cross-section that partially encloses a void, in which the area of the void is substantially greater than the square of the width of the gap, otherwise classified as a hollow as follows.

Ullrich Aluminium Australian Aluminium Council Ltd