How Are Aluminum Profiles Extruded?

Release time:2022-07-22

Many industries widely use aluminum profiles due to their valuable qualities, including high strength-to-weight ratio, durability, corrosion resistance, recyclability, and environmental friendliness. According to Technavio, the industry demand for aluminum extrusions has increased by around 4 % globally between 2019 and 2023. 

Since aluminum profiles have numerous crucial applications in construction and manufacturing, each product demands impeccable precision and quality. You may be wondering how exactly manufacturers produce best-in-class profiles. Herein is a comprehensive overview of the aluminum profile extrusion process.

What Is The Extrusion of Aluminum?

Aluminum extrusion refers to a technique manufacturers use to fabricate aluminum profiles. The process involves forcing a solid piece (sheet, plate, or bar) of aluminum alloy through a die, known as an extrusion die, with a defined cross-sectional profile. 

Aluminum extrusion leverages the unique physical properties of the metal. In particular, malleability and low density allow for easy machining and casting. As such, manufacturers can utilize extrusion to produce various types of profiles, from simple and complex to solid and hollow. 

Manufacturers can also apply additional methods during this process to customize the aluminum extrusions further. For instance, pins can be placed inside the die to produce hollow sections within the product. 

Extrusion Process

To visualize the aluminum extrusion process, you can think of the mechanism of the Play-Doh Shape Maker. The malleable Play-Doh flows through the opening of the press in the shape of the chosen mold as the user squeezes it through. Of course, the aluminum extrusion process is significantly more complex, requiring a hydraulic press and ancillary equipment. 

Nonetheless, the basic principle is similar, and manufacturers can leverage the technique to produce a wide range of aluminum profiles with the appropriate extrusion dies. Extrusion companies utilize two main types of extrusion processes – direct and indirect extrusion.

Direct Extrusion

This method produces less friction than the direct method, which results in better heat regulation. Indirect extrusions typically produce higher-quality products that are more consistent. It might be a result of the applied force being largely constant. Additionally, the stability of the temperature guarantees improved grain structure and mechanical qualities.

Indirect Extrusion

The indirect procedure, also referred to as backward extrusion, is distinct from the direct method. Here, the container and billet move concurrently while the die stays motionless. Manufacturers conduct this technique using a "stem." 

The stem that holds the ram in position must be larger than the size of the container. As a result, the stationary die is pushed through with the aluminum billet. This method produces less friction than the direct method, which results in better heat regulation. 

Indirect extrusions typically produce higher-quality products that are more consistent. It might be a result of the applied force being largely constant. Additionally, the stability of the temperature guarantees improved grain structure and mechanical qualities.

The Aluminum Extrusion Process Step-by-Step

The aluminum extrusion process comprises several important steps detailed below:

The first step involves choosing the appropriate aluminum alloy and designing the final shape of the finished profile. This crucial step largely determines the type of extrusion die and tooling that a manufacturer will use. A long cast of alloy material feedstock, referred to as an aluminum billet, is heated in a heating furnace.

Aluminum melts at around 660° Celsius (1220° Fahrenheit). For the extrusion process, manufacturers typically heat the aluminum billet to temperatures between 375° C (700° F) Celsius and 500° C (930° F). The precise temperature will depend on the aluminum alloy being extruded. Following this heating process, the billet stays solid but is softened considerably and more malleable.

The selected extrusion die is also preheated before being loaded into the extruder. Manufacturers heat the die to a temperature of approximately 500° Celsius. Preheating the die ensures the aluminum flows evenly during the extrusion process.

The next step is transferring the preheated aluminum billet into the extrusion machine. An extruder features a container into which manufacturers place the billet following the application of an industrial lubricant. The extrusion process begins when the extruder’s press ram applies tons of pressure to the billet within this container. 

Note that the powerful hydraulic presses can exert up to 15,000 tons of pressure. The capacity of a specific extruder determines the size of extrusions it can produce. Manufacturers also lubricate the press ram to ensure it doesn’t stick to the aluminum billet during extrusion.

As the press ram applies pressure to the billet, it is pressed against the die. The billet shortens and widens until the walls of the container impede its expansion. Consequently, the softened but still solid billet is forced out through the die opening under continuous pressure. It emerges as a fully fabricated aluminum extrusion profile.  

Manufacturers then cut off the formed profile at the die aperture using a hot saw. Any remaining metal is removed for recycling purposes. After leaving the die, the aluminum extrusion is still hot and undergoes a process known as quenching. 

Quenching is a method used to bring the aluminum profile back to room temperature quickly after extrusion. This crucial step helps prevent changes in the profile’s microstructure that may occur during the cooling process. Manufacturers use various quenching techniques, including soft industrial water, forced air convection (industrial fans), air-mist cooling, and pressure sprays. The cut aluminum profile is moved to a cooling plain, where it cools to room temperature.

Stretching, a form of mechanical treatment, can begin once the aluminum profile reaches room temperature. This corrective process helps fix bends, twists, or bows, which may be present on the profile following extrusion and cooling. Extrusion machines have stretchers that apply a pulling force on either end of the aluminum profile. Manufacturers conduct stretching and straightening to a level that meets the profile’s specified application requirements.

The mechanically treated aluminum extrusions are then cut to the required lengths. Manufacturers may choose to age the profile at room temperature or in an oven to improve their physical performance or metallurgical properties. The final step in the extrusion process is fabrication and surface finishing. 

Fabrication encompasses cutting, machining, welding, and assembling into specific final products. Surface finishing helps enhance the profiles’ aesthetics and corrosion resistance. The common types of finishes include painting, powder coating, anodizing, resin-based coating, and mill finish.    

Conclusion

Overall, producing items with unique cross-sectional profiles requires the aluminum extrusion technique. It is an exciting process that yields a variety of product shapes that manufacturers can heat-treat, construct, and polish to your specifications. For successful applications, it’s important to source extruded aluminum profiles from trusted and respected manufacturers.   

JMA Aluminium is one of the leading suppliers of custom aluminum extrusions. We are dedicated to providing high-quality aluminum extrusion products for residential, commercial, and industrial applications. Get in touch with JMA Aluminium today to learn more about our offerings and bring your project to life.