Extrusion  
 
 

 

Profile designing

Die designing

Die machining

Extrusion

Anodizing

Powder coating

Wrapping

Fabrication

Aluminium glossary


 
 
 Various stages of aluminium extrusion process                                              
 

Aluminium alloys

 

Pure aluminium is relatively soft. To overcome this, the metal can be alloyed and/or cold worked. Most of the aluminium reaching the marketplace has been alloyed with at least one other element.
There is a long-established international system for identifying aluminium alloys (see the table below). The first digit in the four-digit alloy code identifies the major alloying element.The European standard uses the same codes.

The table below gives the broad outline of the systems.

Alloying element Alloy code Alloy type
None (pure aluminium) 1000 series Not hardenable
Copper 2000 series Hardenable
Manganese 3000 series Not hardenable
Silicon 4000 series Not hardenable
Magnesium 5000 series Not hardenable
Magnesium + silicon 6000 series Hardenable
Zinc 7000 series Hardenable
Other 8000 series

The 6000 series is by far the most widely used alloy in aluminium extrusion.
As cold working is the only way to increase the strength of the alloys that cannot be hardened, most of these go for rolling. In extrusion, on the other hand, hardenable alloys are the most commonly used.

The 6000 series, which has silicon and magnesium as the alloying elements, is by far the most widely used in extrusion. In a 7021 alloy, zinc and magnesium are responsible for the hardening effect. Some alloys use manganese, zirconium or chrome to increase toughness.
Iron, which is found in all commercial aluminium, can have a negative effect on toughness and finish (amongst other things) if present in high quantities.

Two hardening methods are used on alloys in the extrusion process. ‘Solution’ heat treatment is carried out during extrusion by carefully controlling the temperature of the emerging profile. ‘Precipitation’ hardening (ageing), which takes a few hours, occurs in special furnaces after the extrusion process.

Amongst the factors affecting the choice of the right alloy for an extruded product are:
– Strength, finish, suitability for decorative anodising, corrosion resistance, suitability for machining and forming, weldability and production costs.

 

 

Go starting

 
When finished creating the die shape design, the extrusion process begins in the furnace for heating cylindrical billets of aluminum alloy where the material is heated to a temperature of extrusion, about 500~600 ° C to prepare for the next step.
 
Photo: direct press
Direct Press
1.Counter platen; 2.Die slide or rotary die head; 3.Shear; 4.Billet container;
5.Moving crosshead; 6Stem; 7.Mandrel; 8.Piercer; 9;Cylinder crosshead; 10.Oil tank
 
Photo: indirect press
Indirect Press
1.Counter platen; 2.Die slide; 3.Shear; 4.Billet container;
5.Moving crosshead; 6.Die stem; 7.Sealing element; 8.Cylinder crosshead; 9.Oil tank.
 
Then the guillotine cut billet to the required length and through the tray is delivered to the press. In the press billet is placed in a container at the end of which there is a die.
 
By pressing billet, hot aluminum is squeezed through a steel die which gives the desired shape of the profile. The die can extrude from one to several profiles depending on the size and weight of extruded profiles.
 
 

Theoretically can extrude profiles of any profile sections - the shape is limited only by the die strength and plastic properties of aluminum. Outgoing profiles are cooled by air or water spray depending on the desired mechanical properties.

 



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