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Forming & Fabricating

  • What is crazing?

    Crazing is a typical phenomenon on pre-anodised aluminium and is a micro-cracking of the anodic layer.  It occurs after re-coiling the anodised aluminium and the cracks are perpendicular to the rolling direction.  The crazing, caused during recoiling, is homogeneous and therefore less visible. 

    Pre-anodised aluminium is more sensitive to crazing with higher anodic layer thicknesses (> 10 µm) and with higher gauges (> 1.5 mm).

    Crazing has no influence on corrosion resistance.

    Post-anodising transformation can result in increased and inhomogeneous crazing and, therefore, specific know-how on further processing, such as cut-to-length is very important.

  • Can pre-anodised aluminium be welded?

    Yes, but first you need to remove the anodic layer at the welding areas.

  • Can pre-anodised aluminium be cut-to-length?

    Yes, with the right know-how.

    Special attention should be given on the cleaning of the CTL line before processing, including:

    • Removal of aluminium particles
    • Pull cleaning felt through the line
    • Working in production campaigns

    During cut-to-length; take into account :

    • Use oil or lubricant during leveling.
    • Too much pressure can crack the anodic layer
    • For higher gauges (> 2 mm) or higher anodic layer thicknesses (> 10 µm), apply protection film after leveling.
  • Up to which temperatures is continuously pre-anodised aluminium resistant?

    • Temperature < 80°C: the anodic layer is not affected.
    • >80°C < 180°C: exposure to these temperatures will cause a more pronounced thermal crazing but the influence on visual appearance will be minimal.  Some decrease in corrosion resistance may be experienced.
    • Temperature > 180°C: exposure to these temperatures will result in a pronounced thermal crazing, a decrease in corrosion resistance and might result in severe damage of the anodic layer.
  • How scratch resistant is continuously pre-anodised aluminium?

    Continuously pre-anodised aluminium is hard like glass, measuring 8 on the Mohs scale; the anodic film is more flexible than batch anodised aluminium permitting easier post transformation.

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