Are you unsure whether to choose cast iron vs cast aluminium for your next product line? Wondering about their weight, strength, corrosion resistance, or thermal conductivity? Do you want a clear breakdown of which metal performs better in real-world applications?

Cast iron and cast aluminium are both widely used in industrial manufacturing—but they behave very differently under pressure, heat, and environmental exposure. This guide will help you compare their properties and decide which material is truly best for your needs.

You’re only one read away from saving thousands in production and performance mistakes. Let’s dive in.

What Is Cast Iron?

Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. It is produced by melting iron with high levels of carbon, silicon, and manganese, then casting it into molds.

Cast iron is strong, heavy, and brittle, making it ideal for compressive strength applications such as engine blocks, manhole covers, gear housings, and machine bases. Its relatively low melting point (~1150–1200°C) makes it easier to cast into complex shapes, although it is not very ductile.

There are several types of cast iron, including:

• Gray cast iron: Known for good vibration damping and thermal conductivity.
• Ductile (nodular) cast iron: Offers better flexibility and toughness.
• White cast iron: Very hard and wear-resistant but brittle.

Advantages of Cast Iron:

• Excellent wear resistance
• High compressive strength
• Stable under thermal cycling
• Good vibration damping
• Cost-effective for heavy-duty components

Limitations:

• Very heavy
• Brittle under tension or impact
• Requires preheating when welding
• Susceptible to corrosion without treatment

What Is Cast Aluminium?

Cast aluminium is a lightweight non-ferrous alloy, usually made from aluminium combined with elements like silicon, copper, or magnesium. It is formed by melting the alloy and pouring it into molds using gravity, die, or sand casting methods.

With a melting point of about 660°C, aluminium is easier to melt than iron, and its low density (about 2.7 g/cm³) makes it extremely popular for weight-sensitive applications such as automotive parts, aircraft components, and heat exchangers.

Advantages of Cast Aluminium:

• Lightweight and corrosion-resistant
• Excellent thermal and electrical conductivity
• Easy to machine and cast into complex shapes
• Recyclable and eco-friendly
• No rusting under most conditions

Limitations:

• Lower tensile and yield strength than cast iron
• Softer—more prone to surface scratches
• May deform under prolonged heat or pressure
• Cost can vary depending on alloy grade

Cast aluminium is widely used in transportation, aerospace, construction, and consumer electronics, where weight savings and corrosion resistance are prioritized over brute strength.

Cast Iron vs Cast Aluminium: Key Differences in One Place

Here’s where we dive deep into how cast iron and cast aluminium compare side-by-side across critical manufacturing criteria.

➤ Strength and Durability

Cast iron offers superior compressive strength and long-term structural integrity, making it ideal for load-bearing components and machinery that faces extreme pressure. It resists deformation but may crack under impact due to brittleness.

Cast aluminium, on the other hand, is more ductile and lightweight, but has lower strength, especially in high-pressure environments. However, it performs better in corrosive environments and in situations where weight reduction is critical.

➤ Weight and Density

• Cast Iron: ~7.2 g/cm³
• Cast Aluminium: ~2.7 g/cm³

Cast aluminium is about 60% lighter than cast iron, which can drastically reduce shipping costs and improve fuel efficiency in mobile applications.

➤ Melting Point

• Cast Iron: 1150–1200°C
• Cast Aluminium: 600–660°C

Lower melting temperatures of aluminium mean it is easier and cheaper to melt and cast, but also means it can deform under heat more easily.

➤ Thermal Conductivity

• Cast Aluminium: ~200 W/mK
• Cast Iron: ~50–80 W/mK

Aluminium is far superior in heat dissipation, making it ideal for engine parts, radiators, and electronics housings. Cast iron retains heat longer, which is better for cookware and engine blocks that require consistent temperature.

➤ Machinability

Cast aluminium is much easier to machine. It causes less tool wear, has smoother cutting properties, and produces finer chips.

Cast iron can be abrasive, depending on carbon content. It often requires special tooling and generates more dust, which needs dust collection systems.

➤ Corrosion Resistance

Cast iron must be coated or painted to resist rust. It oxidizes quickly when exposed to moisture and oxygen.

Cast aluminium is naturally corrosion-resistant, especially in dry or marine environments. Some alloys may still oxidize, but the oxide layer is protective rather than destructive.

➤ Cost

Material costs vary, but generally:

• Cast Iron: Cheaper in raw form and for mass production
• Cast Aluminium: More expensive per kg, but cost can be offset by lighter shipping and lower machining cost

Which One Should You Choose?

Here’s a quick decision-making guide based on your application type:

Choose cast iron if your priorities are:

• Extreme strength and rigidity
• Long-term mechanical stability
• Cost-effective mass production

Choose cast aluminium if you need:

• Lightweight performance
• Corrosion protection
• Better thermal conductivity

Still unsure? Ask your supplier for material samples or custom engineering support.

Conclusion

Cast iron vs cast aluminium is not a one-size-fits-all decision. Each metal excels in specific applications. Cast iron is perfect for durability and stability under pressure. Cast aluminium is your go-to for lightweight and corrosion resistance. Know your product’s environment—and choose wisely.