Aluminium, renowned for it’s versatility and extensive applications, can be processed in many ways to suit different needs. Two of the most common methods of shaping aluminium are casting and extrusion. While both processes transform aluminium into useful products, they have distinct differences in their methods and the characteristics of the final products. Understanding these differences is important for selecting the right type of aluminium for specific applications.

What is Cast Aluminium?

Cast aluminium involves pouring molten aluminium into a mould to create a specific shape. This process allows for the creation of intricate designs that would be difficult to achieve through other methods. The casting process includes several steps:

  1. Melting: Aluminium is heated until it reaches it’s melting point.
  2. Pouring: The molten aluminium is poured into a mould, which is often made from sand, metal, or a combination of materials.
  3. Cooling: The mould is then cooled, allowing the aluminium to solidify into the desired shape.
  4. Finishing: The solidified part is removed from the mould and often undergoes further processing, such as machinery, heat treatment, or surface finishing.

Benefits of Cast Aluminium

  • Complex Geometries: Cast aluminium is ideal for producing parts with intricate shapes and complex geometries, which are often required in the automotive and aerospace industries.
  • Cost-Effective for Large Parts: Casting is generally more economical for producing large components as it reduces the need for extensive machining.
  • Range of Alloys: A wide range of aluminium alloys can be used in casting, allowing for customisation based on specific strength, weight, and durability requirements.

What is Extruded Aluminium?

Extruded aluminium is created by forcing aluminium through a die to produce objects with a fixed cross-sectional profile. The extrusion process involves the following steps:

  1. Billet Preparation: Aluminium billets (cylindrical blocks) are heated to make them malleable.
  2. Extrusion: The heated billet is pushed through a die of the desired shape using a hydraulic press.
  3. Cooling: The extruded aluminium is cooled and then stretched to straighten it.
  4. Cutting and Finishing: The extruded sections are cut to length and may undergo further finishing processes such as anodising or painting.

Benefits of Extruded Aluminium

  • Continuous Profiles: Extrusion is excellent for producing long sections of uniform cross-sections, such as pipes, rods, and rails.
  • Strength and Precision: Extruded aluminium often has high structural integrity and precision, making it suitable for construction, transportation, and consumer electronics.
  • Flexibility: The extrusion process allows for rapid adjustments and changes to the profile, making it versatile for different design requirements.

Key Differences Between Cast and Extruded Aluminium

  1. Process: The primary difference lies in the manufacturing process. Casting involves pouring molten aluminium into moulds, while extrusion involves forcing solid aluminium through a die.
  2. Complexity of Shapes: Cast aluminium is better suited for complex, intricate shapes, whereas extruded aluminium is ideal for long, uniform cross-sectional profiles.
  3. Strength and Durability: Generally, extruded aluminium can offer great strength and consistency in mechanical properties due to the controlled process of extrusion. Cast aluminium, however, can have variations in strength due to potential inclusions and porosity in the casting.
  4. Applications: Cast aluminium is commonly used for parts that require complex shapes and high detail, such as engine components and housings. Extruded aluminium is often used for structural applications like frames, beams, and rails.
  5. Cost Considerations: Casting is often more cost-effective for large, complex parts, especially when the quantities are high. Extrusion, on the other hand, can be more economical for producing long, straight sections in bulk.

Aluminium Extrusion at Simmal Aluminium

Here at Simmal, we are an established provider of aluminium extrusion in it’s wide range of forms. From large, single lengths to the manufacture of precision components, we have the know-how to help you complete your project.

For more information on what we can offer, please contact us today on 01772 324277 or email us at

Contact us today about our services on 01772 324277

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