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
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.
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.
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 ).
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.
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!
MIL-SPEC (Military Specification) standards are established by various government bodies to ensure the reliability, compatibility, and performance of materials and equipment used in military applications. When it comes to choosing between aluminum and mild steel for MIL-SPEC applications, several factors need to be considered: Strength and Durability: Mild steel generally offers higher tensile and yield strength compared to aluminum. This makes mild steel more suitable for applications where strength and durability are critical, such as structural components or armor. Weight: Aluminum is significantly lighter than mild steel, making it an ideal choice for applications where weight reduction is important, like aerospace or portable equipment. This can contribute to better fuel efficiency, increased mobility, and ease of transport. Corrosion Resistance: Aluminum has a natural oxide layer that provides good corrosion resistance. However, mild steel requires proper coating or treatment to prevent corrosion. In corrosive environments, aluminum might be a better choice to ensure longevity and reduce maintenance needs. Machinability: Mild steel is generally easier to machine and work with compared to aluminum. This can be an important factor in manufacturing and repair processes, especially in field conditions. Conductivity: Aluminum is an excellent conductor of electricity, making it suitable for applications where electrical conductivity is required. Mild steel, on the other hand, can be prone to electrical resistance. Heat Resistance: Mild steel tends to have better heat resistance than aluminum. This might be important in applications where components are exposed to high temperatures or rapid temperature changes. Cost: The cost of materials can vary, but in general, aluminum tends to be more expensive than mild steel. This cost difference might impact decisions, especially for large-scale applications. Weldability: Both aluminum and mild steel can be welded, but the processes and considerations differ. Aluminum requires specialized techniques due to its lower melting point and higher thermal conductivity. Aesthetics: Aluminum is often preferred when aesthetics and appearance matter. Its natural finish can be more visually appealing than the utilitarian look of mild steel. In the end, the choice between aluminum and mild steel in MIL-SPEC applications will depend on the specific requirements of the application. Factors such as the operational environment, required strength, weight limitations, corrosion resistance, and budget considerations will all play a role in determining the most suitable material. It's important to carefully assess the trade-offs and consult the relevant MIL-SPEC guidelines to make an informed decision.
