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Solid extrusions
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Hollow extrusions
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Semihollow extrusions
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The relationship between the cross-sectional area of the opening and the square of the opening in the extrusion hole determines whether the extrusion is semi-hollow or not.
Extrusion dies
Hollow dies or solid dies
The dies for solid extrusions consist of a flat plate which forms the external shape of the extrusion. The dies for hollow extrusions consist of two parts where the aluminium flows through the ports and then rewelds as it flows over the mandrel during pressing. The other die part creates the extrusion’s outside surface.
Up to twelve extrusions – depending on the size – can be pressed in multi-cavity dies.
The dies are made of high temperature resistant steel and the die’s opening is made by wire erosion in CNC controlled machines.
Occasionally open extrusions have a design that makes the use of a flat die inappropriate. A die with a deep tongue and a narrow gap will not withstand the extrusion pressure. Therefore the die will be designed with a mandrel to support the tongue even though the extrusion is open.
