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  • MIL-SPEC (general) using aluminum vs mild steel

    Discussion in 'The main mechanical design forum' started by ViewGator91, Aug 7, 2013.

    1. ViewGator91

      ViewGator91 New Member

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      My company designs explosion proof A/C units. A small percentage of our business is military and these units can only be made from aluminum.

      Can anyone tell me WHY... We make commercial units out of other materials, but the military is very pro aluminum and I was just wondering if there was a good answer as to why.

      These have to be explosion proof and very rugged. Pass drop test from 30' and so forth.

      Oh yeah, hello all, I'm new to this forum!

      ViewGator91
       
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    3. Mark Stapleton

      Mark Stapleton Active Member

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      Are these units to be used in maritime (naval) applications or in other transportation? If so the reason may be either weight or resistance to corrosion, and of course if it's the latter (especially in maritime applications) you would need to avoid using stainless fasteners (electrolytic coupling). "Naval brass" (closer to bronze than brass) is, in that sense, even better than aluminum but of course there's no weight saving there - just the opposite - and it's expensive. It's really hard to say unless you can find out more about how these units are to be used.
       
    4. maniacal_engineer

      maniacal_engineer Well-Known Member

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      you are using "why", and "military requirements" in the same sentence; this is not rational. There may be a reason, buried in antiquity or some back office, but finding it will be hard, and getting changed will be nigh on impossible.
       
    5. vidgolob

      vidgolob Active Member

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      The first reason to consider aluminium as a solution is because of its weight. Aluminium actually is not corrosion resistant, especially in harsh environments ( BUT compared to stainless steel its A LOT better in that aspect ). Another reason to consider is price - aluminium is a lot cheaper ( at least here in Europe ) and machining it is also cheaper ( and easier ).
       
    6. srdfmc

      srdfmc Well-Known Member

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      Al is a lightweight material, corrosion proof (much better in fact than other at the same price level as was said earlier) but mostly it can absorb high strain rate such as crash and.. explosion. It does not tears easily.

      Another material, much cheaper, than you could submit to your customer is the HSS: High Strength Steel. The entire auto-industry has switched toward this new kind of steel for its crash-worthiness qualities that it brings at a low weight (low price) level. Its price is now down to that of a mild steel (and even cheaper if you source it right).

      However, depending of your production rate and processes or magnetic impulse requirement, the Al might be the only right solution.

      Why don't you ask tho old one in your company? Goes down to the workshop and ask any metal worker you can find old enough. Usually one or an other own the answer.
       
    7. KevinK

      KevinK New Member

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      Really? I'm no corrosion expert, but I thought the hard oxide coating aluminum tends to form in air provides excellent corrosion resistance? Am I mistaken?

      I'm also new here, so hello all!
       

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