What is the Aluminum Extrusion Process?

September 29, 2020

What is the aluminum extrusion process?

  1. Preparation of Die Tooling
  2. Heating of Aluminum Billet
  3. Press-Loading
  4. Transfer of Billet Into the Press
  5. Aluminum Quenching
  6. Shearing
  7. Cooling
  8. Cutting

Have you ever wondered about the process behind many of the aluminum products you see everyday? After all, aluminum has a wide variety of applications, whether it be decorative, structural, or industrial. Many of the fabricated aluminum components that you see today are the result of the aluminum extrusion process — without which, none of these fabricated parts would be possible. Read on to learn more about the process.

Preparation of Die Tooling

Before the extrusion process begins, a die tooling is first set up on the extrusion machine. These are often steel discs that contain the particular cross-section of the resulting extruded product.

Typically, these steel dies are further categorized into solid, semi-hollow, and hollow, depending on the kind of extruded product which the manufacturer intends. With the shape of the die, it’s possible to manufacture a wide range of aluminum extrusions, like tubes, window frames, hollow beam profiles, L-shaped profiles, and the like.

Due to the average wear and tear, aluminum manufacturers need to constantly have the tooling discs replaced. This is to ensure that there would be no surface defects during extrusion.

Heating of Aluminum Billet

Aluminum billets ready to be heated

The extrusion process starts out with the heating of an aluminum billet, or a solid log-shaped block of aluminum. By heating the billet, it’s easier to hydraulically force it into the die in order to get the desired shape and form.

Billets are not melted during the aluminum extrusion process, as some people may mistake. Instead, they’re heated in a temperature range of 375 degrees Celsius, up to 500 degrees Celsius — just enough to soften the material.

Press Loading

After both the die tooling and the billet are heated, they’re then passed onto the extrusion machine, where temperature and pressure both play a role in the hydraulic mechanism. Generally, the machine is divided into the following parts: main cylinder, ram, dummy block, container, loadout table, cradle, shears, and canister.

As the billet is being loaded into the press, it’s guided by the container which holds it in place while hydraulic pressure is applied from the main cylinder. The loadout table supports the billet while it is being heated by the oven.

Transfer of Billet Onto the Press

Billets being transferred into a press

As mentioned before, the billet needs to be first heated into a specific temperature range before its shape can be affected by the die’s cross-section. After the billet is cradled onto the loadout table, it is then carefully conveyed onto the extrusion press.

Due to errors in the extrusion process, it may oftentimes be the case that the billet gets attached to the ram. For this reason, a small amount of lubricant is applied onto the surface of both the extrusion ram and the billet to eliminate any manufacturing defects.

Through a high-powered hydraulic pressure and ample temperature, the ram is able to pass the heated billet into the die. It then takes the form of the cross-sectional openings as it’s being discharged on the other end.

Aluminum Quenching

Quenching refers to a kind of heat treatment process wherein certain metals — in this case, the aluminum alloy — are heated beyond their recrystallization point before they’re subject to rapid cooling. The purpose of this technique is to improve on the hardness and strength of the alloy.

As the aluminum extrusion is being guided on the other end of the die, it undergoes quenching either by air or water medium. This process effectively alters the aluminum’s grain structure, giving it a uniform shape throughout the extruded material.

Shearing

Aluminum factory working doing shearing

Shears are a part of the extrusion machine. They’re essentially designed to separate the extruded product from the process. Throughout this stage, it’s important that a consistent rate of temperature is applied.

Apart from separating the extruded material from the press, shears also help in removing unwanted materials on the surface of the extrusion. These may be excesses of aluminum film that may have stuck onto the surface of the extrusion during the die tooling phase.

Cooling

The quenching process is finalized in the cooling phase. After shearing the extrusion, it is then loaded onto a cooling rack. The extruded parts are placed onto the metal until such time that they have already reached room temperature.

Though the cooling stage might be a simple process, this is one of the critical steps to ensure that the shape of the extrusion is uniform throughout. Overall, all the stages in aluminum extrusion are critical in defining the shape of the final product.

Cutting

A factory working cutting aluminum

Once the extrusion has reached room temperature, it’s then brought onto a saw table where they’re cut into the desired length of the extrusion. This is ultimately dependent on what kind of product that the manufacturer is aiming for. Tubes may require longer lengths, while aluminum profiles might be of a shorter length.

After cutting the extrusion, they can now be prepared for other surface finish and powder coating treatments to better enhance the design and quality of the extruded aluminum.

Key Takeaway

The aluminum extrusion process is a multi-step method of fabricating aluminum into different parts. Some of the common products of this technique include tubes, window frames, and other types of profiles.

Throughout aluminum extrusion, it’s important that there is uniformity in the application of heat and pressure to avoid any problems. Post-processing techniques like powder coating are then applied onto the extruded material for both functional and decorative purposes.

Acumaster is the leading supplier of aluminum profiles that have been shaped by extrusion. Click here to learn more about their other products and services.


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