Steel, Aluminum, or Stainless? Here’s How We Decide.

We get asked about material choice all the time, and usually the question is some version of, “What’s the best metal to make this out of?”

Well…what are you doing with it?

There really isn’t a best material. Steel, aluminum, and stainless all have things they’re really good at, and they all have things that make them a pain in the ass. The trick isn’t picking the “best” one. It’s figuring out what matters for the thing you’re actually building.

Does it need to be light? Is it going outside? Is somebody going to stand on it? Does it need to look pretty? Are you making one or a thousand? And probably the question that gets forgotten most often…how much do you want to spend?

Those answers usually make the material decision a whole lot easier.

There’s a Reason We Build So Much Stuff Out of Steel

If there’s no compelling reason to use something else, steel is usually a pretty good place to start.

It’s strong, relatively inexpensive, easy to get, and we can cut it, bend it, weld it, machine it, and generally do whatever we need to do with it without too much drama. There’s a reason you see it everywhere.

The obvious downside is rust. Leave a piece of bare steel outside in Georgia and it’ll start reminding you pretty quickly that we have humidity here. But that’s also why paint, powder coat, galvanizing, and a whole bunch of other finishes exist. “It’s going outside” doesn’t automatically mean it needs to be stainless.

And that’s a conversation we have fairly often. Somebody will come in thinking they need stainless because the part is going to see some weather, when regular steel with the right finish will do the job just fine and cost a lot less.

Now, if it’s going to live at the bottom of a swimming pool…we’re having a different conversation.

Aluminum Is Great…When You Actually Need Aluminum

Usually the first reason somebody wants aluminum is weight.

And that’s a good reason.

If we’re building something you’re going to carry around, something that moves, something hanging off a vehicle, or something where taking a bunch of weight out of the finished assembly actually matters, aluminum starts looking pretty attractive.

It also doesn’t rust like steel does, which is nice.

But aluminum isn’t just lightweight steel.

That’s where people sometimes get themselves into trouble. You can’t necessarily take a part that’s made from 1/8-inch steel, make the exact same thing out of 1/8-inch aluminum, and expect it to behave the same way. Aluminum has its own rules. It moves around when you weld it, it handles loads differently, and depending on what you’re building, you may need more material or a different design to get the result you want.

So yes, aluminum is lighter…but sometimes you have to use more of it.

Which is one of those things that sounds obvious after somebody says it.

It’s also generally going to cost you more than mild steel, both in material and sometimes in the amount of work involved. If saving 40 pounds matters, great. If the thing is getting bolted to a concrete floor and never moving again…I’m probably going to ask why we’re paying for aluminum.

Stainless Is Not Just Fancy Steel

Stainless is where people tend to assume they’re automatically getting an “upgrade.”

Sometimes they are.

Sometimes they’re just spending more money.

Stainless makes a ton of sense anywhere corrosion resistance really matters. Food equipment, certain chemical environments, places that stay wet, things that need to be cleaned constantly…there are plenty of applications where stainless isn’t a luxury. It’s the right material.

It can also look really nice, and sometimes that’s the whole point. There’s nothing wrong with that either. If we’re building something architectural and the finished metal is part of the design, stainless might give you exactly the look you want without needing paint or powder coat.

But if you’re building a workbench that’s going to sit in your garage…do you need a stainless frame?

Probably not.

Can we build you one?

Sure.

I’m not going to stop you.

But I’m probably going to ask the question first.

Sometimes the Design Matters More Than the Material

This is the part of the conversation that I think gets overlooked.

People get really hung up on materials because that’s the thing they know to ask about. “Should this be steel or aluminum?” sounds like the important decision.

Sometimes it isn’t.

A well-designed part made out of a less exotic material can outperform a poorly designed part made out of something expensive. Adding a bend, moving a weld, changing where a load is carried, or adding a gusset in the right place can make a much bigger difference than jumping from one material to another.

We’ve had plenty of projects where somebody came in convinced that the answer was thicker steel. Once we looked at what was actually failing, more steel wasn’t really the answer. The way the part was designed was the problem.

Making a bad design heavier just gives you a heavier bad design.

And this is also where talking to your fabricator before everything is completely set in stone can save you some trouble. We might look at something you’ve designed in stainless and realize we could build it out of steel, powder coat it, and save you a bunch of money. Or we might look at the steel version and tell you that by the time we add everything necessary to make it work, we’d be better off starting with aluminum.

That’s the kind of stuff that’s much easier to change before we’ve started cutting metal.

So…Which One Should You Use?

If you were hoping for a chart that says steel is for this, aluminum is for that, and stainless is for something else…sorry.

That’s not really how we decide.

For most projects, we start with what the part actually has to do. Then we look at the environment it’s going to live in, how much weight matters, how strong it needs to be, what it needs to look like, how we’re going to manufacture it, and what the budget looks like.

Most of the time, one of those factors makes the decision for us.

If it doesn’t…steel is usually a pretty good place to start.

And if you come into the shop absolutely convinced that your project needs to be made out of some expensive, exotic material, we’ll happily take a look at it.

Just don’t be surprised if we ask why.