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Aluminum versus cast iron

Some piston compressors use cast iron and others aluminum. But which is better? Here is a look at their differences and respective benefits

Contact us to learn more

March 23, 2020

Aluminum versus cast iron – Which piston compressor material is best?

Estimated reading time: 5 minutes

Thanks in large part due to their versatility and low cost, piston compressors are among the most common air compressors being used today. They are the right choice for a wide range of applications, from DIY to workshops to dentists.

Once you have concluded that a piston compressor also meets your needs best, there is one more decision to make: aluminum versus cast iron.

If you have used our guide on what type of air compressor to choose, then you will know that the first step in selecting the right material for your compressor (which in this case means the pump, cylinders, flywheel and valves) is to figure out how you want to use your new compressor.

When you know, the choice may be easier than you think – even for a layperson. 

Aluminum versus cast iron – lightweight versus heavy duty

stock-photo-aluminum-315611708

To anybody familiar with metals, the main difference between the two is obvious: Aluminum is much lighter. Despite its low weight, aluminum is very strong.

It features superior malleability and excellent corrosion resistance, is easy to machine, not susceptible to rust formation, and has good electrical and thermal conductivity. The latter is particularly important for piston compressors because it results in good heat dissipation. In addition, aluminum will heat up enough to vaporize any condensate in the oil.

Aluminum’s low density makes it the logical material to use for lightweight compressors that are easier to transport, install, and move around.

Automan AT Compressor
Cast Iron compressor block

Cast iron, on the other hand, is able to withstand high loads. It is a perfect shock absorber. While cast iron is sometimes viewed as problematic because it gives off dust that may be harmful to humans, this is not a problem with Atlas Copco compressors.

Among the advantages of cast iron compressors is also that they have long service intervals and feature a high cooling performance.

Because it is very durable and much heavier than aluminum, cast iron is the perfect material for compressors that need to operate in heavy duty environments and extreme conditions.

One drawback is that cast iron is not very flexible.

Aluminum versus cast iron – your needs decide

Because both materials have distinct advantages, it’s impossible to say which one is better. Ultimately, you have to decide which one is better for you.

However, here is a rule of thumb: If you need a small, flexible compressor, especially for non-stationary use, then aluminum is often the material of choice.

But if durability is most important to you and/or your compressor has to function reliably in tough conditions, then you will probably prefer a cast iron model.

One final note, which is less important for Atlas Copco compressors because of their outstanding durability but should be mentioned in a world in which sustainability is increasingly important: Of the two materials, aluminum is much easier to recycle.

Ask an air system professional about the best options for your needs.