Log Aluminium Extrusion Process

Extrusion Log

These are forged in lengths of as much as 7 meters and obtainable in a variety of alloys and diameters. After casting they’re additional heat-handled, (homogenized), earlier than being equipped to the extrusion plant.

Pre-heating

In most extrusion vegetation as we speak the primary operation is to chop the lengthy extrusion log into appropriate lengths for extrusion based mostly on press capability and the ultimate extruded size. (Sometimes 400 mm to 1000 mm) The lower log or billet is fed into the billet heater the place it’s heated sometimes to 400 – 500 deg.C. The precise temperature will rely upon the alloy, form complexity and different course of parameters.

Extrusion

Extrusion entails urgent a preheated aluminium ingot (450-500°C) underneath excessive stress (1600-6500 tons relying on the scale of the press) by a die the opening of which corresponds to the cross-part of the extrusion. The extrusion press pace (usually 5-80 m/min) is determined by the alloy and the complexity of the die’s opening.

There are two primary forms of extrusion course of – direct and oblique. Within the conventional direct technique the die is stationary.

The pre-heated billet is loaded into the container and squeezed by the die opening, (which corresponds to the cross-part of the extrusion). Typical press sizes vary from 1,600 tones to six,500 tones – enough drive to trigger the aluminium to circulation plastically and exit the die at extrusion speeds within the vary of 5-80 m/min. On the exit of the die the temperature of the extrusion shall be in extra of 500 deg. C. The extruded size could also be so long as 50 meters and should consist of 1 strand or a number of strands of the identical part. With most business alloys the extrusion shall be cooled or quenched because it exits the press.

Cooling

Cooling is carried out for 2 fundamental causes:

  • To allow the next stretching and dealing with of the extruded lengths.
  • As the primary a part of the warmth remedy of age-hardening alloys – these kind the majority of business alloys. This “resolution cooling” operation could also be achieved with air, water or a combination of the 2 relying on the alloy and the ultimate mechanical property necessities. (The usage of resolution on this context is a metallurgical time period referring to what’s taking place within the aluminum extrusion profiles alloy and doesn’t describe the medium used for cooling).
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Stretching and Slicing to Size

The lengthy lengths are transferred throughout the press desk into the stretcher. Right here, stretcher jaws at both finish grip the steel and provides it a managed stretch. This straightens the lengthy lengths and can even have a minor impact on subsequent mechanical properties.

The as much as 50 meter lengthy extrusions are then fed to the noticed conveyor the place they’re lower to the shopper’s required size. Typical buyer lower lengths vary from 2-6 meters, however different lengths might be accommodated. The flexibility to provide longer lengths will rely upon the logistics of the person vegetation and shorter lengths are sometimes achieved by a further re-lower operation off-line.

Ageing

This can be a particular type of warmth remedy and sometimes entails heating the extrusions in ovens to a temperature within the vary of 170-190 deg. C for four to eight hours. This develops the mechanical properties of the extrusions, significantly their power. The minimal mechanical properties that have to be achieved after ageing are specified within the related EN/British Requirements for various alloys and tempers.

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