You and your dining companion ordered from the same menu, but when the food arrives theirs looks so much more appetizing. It’s a familiar problem, but maybe you could avoid it by asking the server for advice. After all, they know what goes on in the kitchen.
It’s the same with choosing metal for your fabrication. You think you know what you want but your server, (which is how we think of ourselves,) might be able to suggest some alternatives. This happens a lot with the aluminum extrusion vs stainless steel decision. (Which perhaps isn’t so different from asking, “chicken or steak?”) If we haven’t made you too hungry, keep reading and we’ll share some pros and cons of these two materials.
Stainless steel is basically iron with sides of nickel, chromium and carbon. Together they make a metal that’s very hard and virtually immune to corrosion. It’s hardness can be an issue though because that makes stainless difficult to machine and form. Bend it too far and it cracks. There again, it’s relatively easy to weld (easier than aluminum anyway,) and can be given a range of attractive finishes.
Aluminum, which starts out as bauxite, is far more ductile. It’s readily machined or formed into complex shapes and can be extruded through a die. It melts at a lower temperature than stainless and is nowhere near as hard. It is corrosion-resistant, but not to the same extent as stainless. Acidic environments and even salt water will eat it away. It’s lightweight though with a density about 1/3rd that of stainless, and that gives it one very interesting property: it has a higher strength-to-weight ratio than stainless.
The Benefits of Extrusion
This strength-to-weight advantage is enhanced by using aluminum in extruded form. Extrusion is an excellent way of putting material just where it’s needed and eliminating it from where it isn’t. As a result, aluminum extrusion is both strong and lightweight. All a designer need do to take advantage of this is design in terms of two dimensional profiles.
If weight is a concern aluminum extrusion might be a better way of providing strength than using stainless. It’s also more machineable and formable, making it easier to cut and shape, but that doesn’t make it the best choice for every application. There are at least three design requirements that might lead you to stainless. These are:
- Elevated service temperatures
If you’re designing for the food or medical sectors, where sterilization processes are a way of life, aluminum probably isn’t the best choice. The same goes for many chemical processing situations. If however, weight reductionand strength top your list of needs, with corrosion-resistance coming third, then aluminum extrusion could be an excellent choice. This is why the automotive and construction industries consume so much of it!
Weighing the Choices
Cost figures in every material selection decision, but so too must the manufacturing implications. Pound-for-pound, aluminum is cheaper than stainless, just as chicken costs less than steak. But then you’ve got to look at what the chef has to do with it.
If aluminum has the properties your application needs it’s probably the way to go, especially if you’re able to use aluminum extrusion. Likewise, it’s usually pretty clear when only stainless will hold up, . But if you find yourself in the middle, unsure of whether to use aluminum extrusion vs. stainless steel, ask your server’s advice. (That’s us!) We know the ingredients, we know what the kitchen has to do, and we want you to like what we make for you.