Interested in trying out some metalworking without investing in special blacksmith equipment? Aluminum has a low melting point, so it’s a great way for beginners to learn how to cast and forge metal objects.
How to forge or cast aluminum. To cast aluminum, you’ll need a way to get it hot enough that it reaches its melting point of 660 degrees C (1200 degrees F.) Then you can either pour it into molds to create ingots, or cast it to create tools and other objects. Aluminum can be shaped and cold forged without any heating, although heating it makes the process easier.
In this article you’ll learn how to create a backyard aluminum forge using household items. Then you’ll learn how you can melt everyday aluminum objects like pop cans down and cast them into pure aluminum ingots. You’ll learn how to cast aluminum using the lost foam method. We’ll also discuss the safety precautions you need to take while working with aluminum, and much more.
Why Forge Aluminum?
Why should you consider working with aluminum as your first metal?
It has a low melting point. Aluminum’s low melting point means that it’s easy to get to a molten state without having to buy a specialized blacksmith’s furnace or forge. You can create a makeshift foundry out of objects you’ve got lying around your house.
Cheap materials. If anybody in your house drinks soda or beer from aluminum cans, then you’ve got a free source of quality aluminum that you can get started with.
Both of these points make aluminum a great choice for beginners who want to start crafting items out of metal.
Making A Backyard Aluminum Forge
You can make your own aluminum forge out of basically any container, as long as it has a higher melting point than aluminum.
Common choices include coffee cans, metal flower pots, and soup cans.
Once you’ve got a container of the size you want, you just need to mix together sand, plaster of paris, and some water to create an insulating layer for your forge.
I think this part is best explained visually. So rather than writing out step by step instructions, I’m just going to refer you to this video by Grant Thompson, aka The King of Random on Youtube. It’s much easier to watch someone do it.
If you want to use a different sized container, try looking up similar tutorials on Youtube and I’m sure you’ll find something.
Making a crucible
Besides a forge, you’ll need to make something to hold your aluminum while it’s melting. That’s what a crucible is. It’s basically just a metal container that you can get very hot without it melting.
Many people suggest cutting an empty fire extinguisher or propane cylinder in half to create your crucible. I DO NOT encourage this, because the container might explode if there is any gas left inside. It’s a big gamble.
Instead I’d look for some kind of cylindrical stainless steel object. The insert from a thermos would work well, and you can coat the outside with the same plaster of paris and play sand mixture that you use to create your forge.
You can use basically any kind of steel container like an empty paint can. It’s best to put a couple holes through and put a rod in that allows you to safely and easily tilt the container. Any metal container will eventually burn through, but the thicker the metal is the longer your crucible will last.
You could also experiment with using a ceramic container, although I haven’t done this personally or seen many other people talk about using a DIY ceramic crucible.
Melting Pop Cans Into Pure Aluminum Ingots
Once you’ve got a working aluminum forge, you can start making ingots.
Aluminum ingots are a convenient way to store your purified metal until you need it for projects.
I recommend crushing down pop cans before you put them in your crucible. That way you might be able to fit a few in at a time.
If your forge is at a high enough temperature, it shouldn’t take any time at all to melt down your cans. They should become molten within a couple of seconds.
You’ll notice a coating on the surface of your liquid aluminum. This is called slag or dross, it’s all of the impurities in the aluminum like the paint that melted off the cans. You’ll want something that you can use to skim or spoon this slag off the top so that it doesn’t go into your ingots.
Act Fast!
Even if you’re working with pure aluminum, it oxidizes and forms a skin on top of the molten metal. So you’ll want to act fast and get your molten metal poured into molds as quick as possible. Expect to lose a percentage of the total aluminum that you put into each batch. If you work with larger quantities of aluminum at a time, you’ll lose less refined aluminum at the end overall.
Once you’ve skimmed the slag off the molten aluminum in your crucible, you can carefully pour it into a mold. Any steel container will work. I’d recommend muffin tins or something similar because it will give you small, easy to work with ingots of pure aluminum.
Here’s another video by Grant showing you how to melt your aluminum cans down and turn them into ingots:
Casting Aluminum Using The Lost Foam Casting Method
You can either cast aluminum straight out of the crucible the first time you melt it down, or you can heat your pure aluminum ingots back up to their melting point at a later time.
There are several different methods of casting aluminum. But here I’ll discuss what I think is the easiest way to do it. It’s called lost foam casting, and you’ll understand why very soon.
The first thing you’ll need to do is find a piece of styrofoam larger than the final object that you want to create out of aluminum. Any kind of styrofoam will do, and you can use other similar materials like home insulation foam board.
You’re going to cut and shape the styrofoam to create an exact replica of the object you want to create out of aluminum. This can be a gear, a statue, or whatever you’d like.
Your styrofoam object will be buried in a bucket of sand, with an opening left at the top for you to pour molten aluminum into.
When you pour the aluminum into the bucket, it will instantly melt the styrofoam and fill the space it left before the sand can collapse in. So you should be left with a perfectly casted aluminum object.
Here is another video to demonstrate these steps, because I know that visually seeing it can be more helpful than just reading about it:
The main tip I’d give you is to avoid making your styrofoam cutout too ornate or elaborate. For your first few casts, try using more simple and straightforward shapes.
The reason is that some deformities like bubbles and air pockets can form in your final product, which is much more noticeable on something like a figurine.
Getting your sand a little wet before casting and making sure it’s really packed down well can help avoid any flaws in your end product.
Can You Cold Forge Aluminum?
If all this talk of getting aluminum molten hot seems like too much work or too dangerous for you, there is an alternative.
You can cold forge aluminum since it’s a pretty malleable metal to begin with. Usually there’s no need to heat it at all. Although a little heat can make it much easier to work with.
The one downside is that aluminum becomes brittle if you overwork it. But it’s a pretty versatile metal that you can make a lot of things with if you’re careful.
To see just how much you can do with cold forging, check out this video of a guy making a kitchen knife out of aluminum foil!
Safety Precautions When Working With Aluminum
The main thing that you should keep in mind when you’re working with aluminum is that you don’t want to inhale any dust or fumes. There’s a pretty strong link between aluminum exposure and neurological disorders like Alzheimer’s, multiple sclerosis, and Parkinson’s disease.
Make sure you’re working with aluminum in a well-ventilated area and use a respirator. Particularly when you’re heating up aluminum and paint or other impurities are being burned off.
As with any kind of metalworking, you’re going to be dealing with very hot materials. So proper protective clothing and footwear are a must. Also handle hot materials in a way to avoid any dropping or spilling.
Forging Aluminum
If you’re a blacksmith then you should be quite familiar with forging. It’s a process where metal is pounded, squeezed, or pressed to shape it the way we want. Aluminum can be forged in a similar way to how blacksmiths forge steel or iron.
The tricky part about forging aluminum is its low melting point, combined with the fact that it goes from a solid to liquid state really fast.
Steel is easy to forge because the transition from solid to liquid is very gradual as it heats up. You’ll know when a piece of steel is starting to go soft and have plenty of warning before it goes liquid. There’s plenty of leeway between the temperature when a piece of steel is soft enough to shape and when it turns in to a puddle.
Aluminum goes from solid to liquid a lot faster. There’s a much smaller window between where it’s soft enough to form and when it will just melt. So you have to be a lot more careful in precise with your temperatures when working with aluminum.
If you want to create a really complex piece of aluminum, it’s usually way easier and less work to simply cast it instead of trying to forge it. But forging aluminum isn’t impossible if you’re up for a challenge.
At home you can forge your aluminum with a basic hammer.
In more industrial settings, presses and larger pieces of machinery are used to forge aluminum. Companies forge aluminum into objects like surgical tools, hammers, wrenches, and garden tools.
There are three main ways that aluminum forging is done by the pros:
Open die forging. It’s the closest to what you think of as forging, with a big power hammer smashing aluminum into the desired shape.
Closed die forging. Closed die forging is also known as impression die forging. A piece of heated aluminum is put on to a mold and then struck, making it take on the shape of the mold. This can create a wider variety of shapes and can create pieces weighing just a couple ounces or several tons. Most aluminum forging is done using closed die forging, since it produces much more complex shapes and also allows for tighter tolerances and better quality control.
Roll ring forging. This forging method is specially designed to create circular rings of aluminum. Usually it starts off with an open die forged ring, which gets punctured like a donut and then stretched out. It can create thick metal rings, or make them flat like a washer.
Related Questions
Q: Why are most metal objects made of steel instead of aluminum?
A: Aluminum is great for specific applications where you need really lightweight metals. But it doesn’t come close to steel in terms of toughness or hardness. That’s why you’ll never see a building made with aluminum beams, or see aluminum knives or tools for sale in stores.
Aluminum does have its part though. Mainly in aircraft parts, racing wheels, scuba tanks, and beverage cans. But even in these cases, an aluminum alloy is typically used and not pure aluminum.
Q: Is there an easy way to get aluminum hot enough to work with but not melt it?
A: You can get a product called a Tempilstik. These are temperature indicating sticks that can be bought to indicate exact temperatures from 100 degrees F all the way to 2000 degrees F. These sticks work by instantly melting when they reach their designed temperature. Since aluminum melts at around 1,200 F, I’d get a Tempilstik designed to melt at about 800 F to give yourself plenty of leeway and avoid having your piece of aluminum turn into a puddle.
Another easy to way to test is to remove your aluminum from the forge and touch it to a piece of newspaper or wood. It should scorch either of these if it’s hot enough to work with. You can also drag it across the surface of your anvil and it should resist dragging a bit and seem tacky if it’s at forging temperature.
Have you ever melted down aluminum at home? Share your experience in the comments below!