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Aluminum extrusion

Dr. Dmitri Kopeliovich

Extrusion

Extrusion is a metal forming process involving shaping a metal billet (hot or cold) by forcing it through a die with an opening.

Extrusion does not produce tensile stresses (only compression and shear) in the deformed metal bar therefore it does not tear.

The two possible schemes of extrusion are presented in the picture:

extrusion.png

The metal billet is placed to the container of the extrusion press. The die with an opening is mounted at the end of the container.
When the hydraulically driven ram presses the billet, the metal starts to flow through the opening forming the extruded product of the required cross section.
In the direct extrusion the extruded metal flows in the direction of the ram motion.
In the indirect extrusion the metal flows in the direction opposite to the ram motion.
Indirect extrusion requires a lower force than direct process as there is no friction between the billet and the inside walls of the container.

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Aluminum extrusion process

Cylindrical billets of extrusion aluminum alloys are fabricated by the Direct Chill (DC) casting method. Aluminum extrusion process is based on a flow of hot and compressed aluminum alloy through the steel die. The aluminum billet is compressed in the heated container of the extrusion press by a hydraulically driven ram.

The diagram below presents the main steps of the aluminum extrusion process:

Fabrication of extruded aluminum profiles

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Extrudability of aluminum alloys

Extrudability of aluminum alloys Extrudability of an alloy is the maximum relative extrusion speed, which allows to obtain extruded profile without tearing and cracks.

Extrudability of an alloy depends on the following factors:

The Aluminum alloys having good extrudability are:

The alloys having moderate extrudability are:

The alloys having poor extrudability are:

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Properties of extruded aluminum alloys

Designation Forming Machining Welding Brazing Protective
anodizing
Aesthetic
anodizing
Temper Tensile strength,
ksi/MPa
Yield strength,
ksi/MPa
Elongation,
%
1060 good poor good good excellent excellent O 1.233 / 8.5 0.363 / 2.5 25
1100 good poor good good good good O 1595 / 11 435 / 3.0 25
2014 good good not
suitable
not
suitable
fair not
suitable
T4 50 / 345 35 / 241 12
2014 good good not
suitable
not
suitable
fair not
suitable
T6 60 / 414 53 / 365 7
2024 good good not
suitable
not
suitable
fair not
suitable
T3 57 / 393 42 / 290 12
2024 good good not
suitable
not
suitable
fair not
suitable
T81 64 / 441 56 / 386 4
3003 excellent fair good good good poor O 14 / 97 5 / 34 25
5083 good good good not
suitable
good good O 39 / 269 16 / 110 14
6061 good good good good good fair T4 26 / 179 16 / 110 16
6061 good good good good good fair T6 38 / 262 35 / 241 8
6063 good good good good good good T1 17 / 117 9 / 62 12
6063 good good good good good good T4 19 / 131 10 / 69 14
6063 good good good good good good T5 22 / 152 16 / 110 8
6063 good good good good good good T6 30 / 207 25 / 172 8
6101 good good good good good good T6 29 / 200 25 / 172 15
6463 good good good good good excellent T1 17 / 117 9 / 62 12
6463 good good good good good excellent T5 22 / 152 16 / 110 8
6463 good good good good good excellent T6 30 / 207 25 / 172 8
7075 fair good not
suitable
not
suitable
fair poor T6 78 / 538 70 / 483 7


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Applications of extruded aluminum

About half of the aluminum products are fabricated by extrusion:


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