Extruded aluminum and Cast aluminum are named after the process chosen to make them. Both aluminum types have different strengths and properties. The preparation and machinery used in both processes are different. The choice of method depends on the needs of your project. The extrusion process is costly compared to aluminum die casting, but it can’t make complex and tedious shapes.

In this guide, we will discuss a few of the properties and methods used, as well as a comparison table to show how they differ from each other and what the benefits of using each method are.

What is Aluminum Extrusion?

Aluminum extrusion is a process used to form different aluminum shapes when passed through different cross-sectional dies. Aluminum extrusion helps in different industries, including electronics, building large structures, the automobile industry, etc. Extruded aluminum is strong and has a great tensile strength. The Aluminum extrusion process involves the steps given below.

1. Preparation of Billet and Die

Billets are usually seen in cylindrical shapes. They are heated at higher temperatures to soften them so they can easily pass through the die to make a shape. Like billets, Die is important as you need it to be precise and well-maintained to get the right shapes.

2. Extrusion

There are two types of extrusions: direct and indirect extrusions. Direct extrusions are those in which a big ram is used to push the aluminum cylinders or billets through the die. The extruded aluminum is passed through the die and forms its shape. The indirect extrusion is one in which the billets are not moved, but the die is moved toward the billet to form a shape. Both of these processes have their perks.

3. Cooling Process and Straightening Process

The extruded aluminum has heat in it and needs to be cooled down to room temperature. It is done through air or water quenching after cooling. The extruded aluminum requires straightening to achieve better straightness.

4. Cutting and Finishing

The cutting and finishing process starts when the aluminum is cut to the required lengths. Then, a finish treatment is applied to keep it safe from corrosion or get a decorative surface.

What is Aluminum Die Casting?

It is a manufacturing process in which aluminum is moulded in different shapes after heating at higher temperatures. The raw aluminum, ingot is used to melt into a liquid form at high temperatures. This process is efficient and helps you get the finest shapes. Here is how aluminum die casting is done.

1. Preparation of the Die

The die is one of the most important parts of aluminum die casting as you need to mould aluminum in different shapes by pouring it into these die shapes. The die is typically made of steel. The hard steel makes the aluminum die-casting process better.

2. Melting Aluminum at Higher temperatures

Aluminum is heated at higher temperatures, like 450-500°C, to give it a liquid shape.

3. Pouring into the Die

The molten aluminum is poured into the die shapes at higher pressures (ranging from 2000-15000 psi). This pressure is required as molten aluminum needs to settle in the die shapes.

4. Cooling Process

Now, the molded aluminum is cooled until it reaches room temperature. The aluminum solidifies in this process, and there is a chance of pores in the final product if the process is not carried out carefully.

5. Finishing

The finishing process includes the separation of the die from the solidified aluminum and further modifications like cutting and trimming the material. This trimming is needed to give the finest shapes possible. Complex shapes usually require these modifications.

Extruded Aluminum vs. Cast Aluminum

Here is a character comparison table for both processes.

Extruded Aluminum Cast Aluminum

Manufacturing process

 A heated aluminum extrusion billet is forced through a die to form a long continuous shape with a fixed cross-sectional profile under high pressure. Aluminum is melted, and injected into a die, cooled and solidified into the desired shape.

Alloys Used

 Usually 6063, 6061, 6060, 6082, 7075, 2024, etc. Usually A356, A380, etc.

Shape

 Long, uniform cross-section Complex shapes and helps get 3D shapes as well.

Design Flexibility

 Relatively simple Much more complex and irregular shapes

Surface Finish

 Smooth surface Relatively poor and rough

Dimensional Tolerances

 Higher tolerances Lower tolerances

Cost

 Cost-effective for large quantity Cost-efficient for small quantity

Weight

 Extrusion allows hollow section design, so the weight is usually ligher for the same volume. May be heavier for a thicker part.

Tensile Strength

 Higher Lower due micro-porosity in cast parts.

Yield Strength

 Higher and used in building tough structures. Lower and cannot be used in structures where high load is required.

Hardness

 The alloy can achieve higher hardness with heat treatment. 7075T6 alloy has replaced steel in some applications. Lower

Fatigue Strength

 Better, and it is more durable under repeated stress. Weaker because of internal voids and inclusions.

Corrosion Resistance

 Better More prone to corrosion due to porosity in the cast aluminum.

Heat Resistance

 Shows solidity at higher temperatures. Great at heat, but the pores and cracks might show different results.

Machinability

 Easier to machine Difficult to machine due to its less uniform structure and potential internal imperfections.

Environmental Impact

 More energy-efficient and environmentally friendly. Recyclable, but the casting process has higher emissions.

Thermal Conductivity

 Good Good, but it may be less efficient because of casting defects.

Impact Resistance

 Good Less resistant to impact because of internal flaws in the casting process.

Weldability

 It is easy to weld for common alloys like 6061 and 6063. It is difficult to weld alloys like 7075 and 2024. Difficult to weld due to its porosity and internal impurities.

Durability

 They are highly durable due to their uniform shapes. Durable, but the casting process defects might reduce the lifespan.

Applications

 Automobiles, Building structures, electronics and aerospace equipment, tools and machinery, windows and doors.  Machinery parts, automotive parts.

Which Process is Better for Your Project?

Aluminum extrusion and aluminum die casting are methods used to form different aluminum shapes for different applications. They have different properties and strengths based on the methods used. However, the best methods to choose is dependent on your product and design.

When you need to have parts that are of complex shape, you need to go for the aluminum die-casting process. This method will help you create fine shapes in automotive parts and components.

If your designed part is of a uniform cross-section, it is best to use aluminum extrusion. It offers a stronger and better finish for your aluminum parts.

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