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  • Can Someone Tell Me About the Basics of Aluminium Extrusion?

    Discussion in 'Metal casting & moulding' started by STRAYGOAT, Jan 7, 2011.

    1. STRAYGOAT

      STRAYGOAT New Member

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      Hello everyone,

      I've got to write a small article about aluminium extrusion design considerations and I was hoping someone might be able to help me (bearing in mind, I know absolutely nothing about the subject other than the handful of web pages I have read).

      From the bits I have read, it would seem that the things you need to consider when designing aluminium extrusions are:

      The thickness of the walls (different thicknesses are possible, but more difficult, so this will force costs up). Avoid sudden changes in thickness as this may compromise strength.
      The strength of the aluminium alloy (depends on what metal is used)
      The anti-corrosive properties of the aluminium alloy (again, depends on metal)
      The electricity conduction properties of the alloy
      The heat conduction properties of the alloy
      Manufacturing limitations - sharp angled corners, twists, flatness are all possible, but only to certain limits depending on alloy, thickness of walls etc.
      Weight - dependent on alloy
      Hardness/Durability
      Surface finish and reflectiveness
      Anodizing response - I have no idea what this means!
      Temper - again, i don't know what this means!
      Loading direction - ????
      Machinability -??????
      Whether it can be welded
      Whether it can be made into complex shapes - depends on alloy?

      What would really help me is if someone could tell me if I have missed anything major and also if they could explain the few terms that I have put ??? next to. I have tried looking them up on line, but so far, every description is pretty jargon-heavy.

      Thanks in advance for your help

      Regards

      C
       
    2.  
    3. nigelwatson

      nigelwatson Guest

      Re: Can Someone Tell Me About the Basics of Aluminium Extrus

      A major consideration that was not included on your list is the relative cost of specific aluminum alloys. Greater cost premiums are charged for alloys such as 6061 or 6005A. Unless specifically requested, it may be desirable to specify alloys like 6060 or 6063 which typically do not have associated higher premiums. The higher costs are related to the material cost of the alloy and the rate (speed) at which the alloys can be extruded. Alloys that have faster extrusion rates are also likely to have smoother surface finishes with associated higher reflectivity.

      Before an aluminum extrusion alloy is specified, it is important to understand the end-use requirements of the extrusions, including the anticipated structural loading (maximum stresses). Following extrusion, the alloy may be heat treated to improve the mechanical properties of the alloy. Generally, heat treatment will increase the hardness, yield strength, and the tensile strength of the alloy. The heat treated condition of an alloy is denoted by the letter T (temper) which is usually followed by one or more numbers i.e. 6061-T6. The temper designation corresponds to the alloy’s minimum mechanical properties.

      Anodizing is an electrolytic finishing process of aluminum, similar to plating. Anodizing generates a thin oxide layer on the surface of the alloy which improves the corrosion resistance of the extrusion. Anodizing “response†may refer to the alloy’s ability to generate a uniform anodized layer. Some alloys contain trace elements that interfere with the formation of a uniform coating. Non uniform coatings may give rise to surface blotches.

      I hope this helps
      Regards,
      Nigel
       
    4. LinkedIn Gopher

      LinkedIn Gopher Little furry chap

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      Re: Can Someone Tell Me About the Basics of Aluminium Extrus

      To make small cylindrical containers, a punch and die are used which produce the inner and outer diameter. The aluminium slug is a cylinder with the diameter slightly smaller than the diameter of the die and its height calculated to give a small excess over the volume of the finished product (the part will be trimmed after pressing, to give the desired length). For processing, the slug is coated with a thin layer of stearate compound to give lubrication. For short parts the tools can be fitted in a toggle press to give a high punch velocity. Longer parts can be made in a hydraulic press. I hope this is useful.

      Source
       
    5. GarethW

      GarethW Chief Clicker Staff Member

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      Re: Can Someone Tell Me About the Basics of Aluminium Extrus

      Hi STRAYGOAT, Would you like to add your finished article to our Knowledge Base? It would be great to have the info available as a tutorial to others. :)
       
    6. Michael

      Michael Active Member

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      Re: Can Someone Tell Me About the Basics of Aluminium Extrus

      Now reading this, I have a question (please forgive me; i'm still a highschool student...); when is the tempering done, before or after extrusion?
       
    7. Chris_jzw

      Chris_jzw New Member

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      it should be tempering after extrusion.
      purpose of termpering is relieve the process stress in the parts,to gain accurate profile and design dimension.
       
    8. frankzhou

      frankzhou New Member

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      maybe you could reference to this standard EN 12020 about the aluminium extrusion dimension, tolerance etc requirements
       
    9. CADJockey

      CADJockey Member

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