The stretching, ageing and strengthening aluminium extrusion process

Continuing our series on deconstructing the aluminium extrusion process, this post looks at the cooling, stretching, cutting and heat treating required to produce the profiles you need.

The billet ‘butt’ that remains from extrusion creation oxides from the billet skin. The butt is sheared off and discarded while another billet is loaded and welded to a previously loaded billet and the extrusion process continues.

When the extrusion reaches a desired length, the extrusion is cut with a profile saw or a shear.

Metal is transferred (via belt or walking beams systems) from the run-out table to the cooling table.

After the aluminium has cooled and moved along the cooling table, it is then moved to the stretcher.

Stretching straightens the extrusions and performs ‘work hardening’ (molecular re-alignment which gives aluminium increased hardness and improved strength).

The next step is sawing. After extrusions have been stretched they are transferred to a saw table and cut to specific lengths. The cutting tolerance on saws is 1/8 inch or greater, depending on saw length.

After the parts have been cut, they are loaded on a transportation device and moved into age ovens.

Heat-treating or artificial aging hardens the metal by speeding the aging process in a controlled temperature environment for a set amount of time.

Want more? Download our free Desperately Seeking Aluminium – Aluminium Extrusion Buyers Guide by INAL here.