Cast Iron vs. Aluminum: What’s the Difference?

Metal casting is over 6000 years old and is still widely practiced today. The metal casting process is the backbone of many industries from mechanical to household goods.

When it comes to metal casting, your choice of metals makes all the difference. There are hundreds of different alloy metals and grades with their own advantages and disadvantages.

Two of the top modern metal casting choices are cast iron and aluminum. But the two are different metals with different properties and uses. In this matchup, here are the major differences.

Cast Iron

One of the major differences between the two is the weight. Cast iron is a much heavier material, and that leads to different applications of the two metals.

Cast iron is an alloy that turns solid through a eutectic. A eutectic is a mixture of substances that solidifies at a temperature lower than the parts’ melting point.

When exposed to damp or humid air, cast iron can oxidize quickly and continue to oxidize if left in these elements. However, some treatments can prevent pieces of the iron from oxidizing.

Malleable irons have great castability and fluidity. They’re resistant to wear and deformation. The machinability quality makes cast iron an excellent engineering material for many applications.


As stated, one of the major differences between these two metals is the weight. Aluminum is very lightweight and low density, which makes this a popular metal for casting in various industries.

Aluminum is especially popular within the construction and transportation industries. It’s even used to create aerospace technology. Aluminum’s corrosion-resistant property makes it a vital material for these industries.

As one of the most abundant metals in Earth’s crust, making up about 8% of Earth’s solid surface. In nature, you would find aluminum mixed with almost 270 different materials, the most common being bauxite ore.

This material is also renowned for its ability to conduct thermal and electrical energy. Aluminum is non-magnetic, non-sparking, and can be corrosion resistant when it’s strong. This allows the metal to become a superconductor.

Applications of Cast Iron and Aluminum

Cast iron is a great metal for various machines, including automotive parts. Cylinder blocks and cylinder heads are also common applications. You may also find it in pipes and gearboxes as well.

Despite the many applications, the usage of cast iron has fallen significantly over the last few years. But it’s still a popular metal alloy to use in the metal casting process.

However, aluminum’s usage has grown. Aluminum casting is widely used throughout the automotive industry. Aluminum-cast products account for over half of the aluminum used in cars.

You can also found cast aluminum as a part of small appliances. Household tools and machinery like lawnmowers are common. And everyday uses like cookware are popular places for aluminum.

Aluminum vs. Cast Iron for Modern Metal Casting

Cast iron and aluminum both have their place in the world of metal casting. And while they have some similarities, the two are very different.

In summary, cast iron is durable, highly resistant to wear and deformation, great in engineering and machinery. At the same time, lightweight aluminum is highly conductive and used in the automotive industry and household products.

We can meet all of your metal casting needs through our wide range of products and industries served. Contact our experts to get a quote on a custom and quality product.