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You are in: Kaye Aluminium Technical Manual > Contents > Extrusion Die Theory
 

Extrusion Die Theory

All Kaye Aluminium dies are manufactured by independent die makers. The hole in the die, which corresponds to the cross section of the finished extrusion, is produced by spark erosion. Dies can be classified into 2 groups, hollow dies, and flat dies .

Large and medium sized extrusions are produced through a die with one single cavity, but for smaller sections, dies with multiple cavities can be used, as long as the required size to weight ratio is observed. (See section DESIGN CONSIDERATIONS )

 
Hollow Dies

Hollow sections are created using a hollow, or "port-hole" die. The solid billet is forced through a die tool called a "bridge" that divides the metal into two or more separate streams (in the case of the figure below, four streams are created). The streams then flow under the bridge to be pressure welded together.

The metal emerges as an extruded section, through the orifice formed between the mandrel nose and the outer section shape that has been cut into the die.

Figure 2.2.01 shows the die plate, in which the outer shape of the proposed section is clearly visible.

 
Material flows into the plate from this side, once it has navigated the bridge (Figure 2.2.02 shows the die bridge itself, which incorporates the mandrel) supported by the four webs that divide the metal up into streams. The mandrel then fits inside the hollow of the plate, to form the desired shape of the final extrusion.

The final figure, 2.2.03, shows the whole die, incorporating both the mandrel and the plate. You can clearly see the mandrel nestling inside the hollow, which gives an idea of what the final shape will look like. It is also clear how problems can be occur with the wall thickness around the mandrel, especially if the mandrel is small. Dies with multiple hollows in the required section incorporate several mandrels. The design team try and avoid these as much as possible.

 
Manufacturing Time

To manufacture a typical flat die would take approximately five to seven full working days.
To manufacture a flat die approaching our maximum size would take approximately ten to twelve full working days.
To manufacture a typical hollow die would take ten to twelve full working days.
To manufacture a hollow die approaching our maximum size would take twelve to fifteen full working days.

These figures are based on dies ordered when the die maker has available capacity. At certain times during the year (company holiday shut-down) delivery times can be drastically afected.

 

Note
As most (including foreign) extruders use the same die makers, deliveries can occasionally become difficult. If a particular order is to be placed on a tight schedule a check of the current die delivery status should be made with the die shop.

     
Copyright 2004