Metal extrusion forces raw metal material through a shaped die to create an elongated final shape. The shape of this die defines the profile of the extruded piece, which can be altered to suit many desired geometries. Due to their physical characteristics, aluminum alloys hold up particularly well to extrusion, and aluminum extrusion as a distinct process is popular for creating diverse components and products across industries.
Compared to alternatives such as die casting, extrusion promises a cost-effective, versatile method of manufacturing high-quality aluminum components.
The Aluminum Extrusion Process
The aluminum extrusion process occurs in multiple steps:
- The first step in the aluminum extrusion process is to determine and craft the proper die shape. This step ensures that the final extrusion is formed properly for its function.
- Next, the aluminum billet must be prepared for the extrusion process. The cylindrical metal form is heated to 800-925° F to allow it to progress through the die, then transferred into the machine.
- The machine applies sufficient pressure to force either the ram or the die itself to move, pushing the billet through the die. Adding liquid or gaseous nitrogen is often useful at this stage to prevent oxidation of either the die or the component itself, extending their working lifespans.
- Once the part has passed fully through the die, it is removed from the machinery and allowed to cool. Finishing work may include straightening, stretching, and sawing to improve specific physical properties or achieve the required geometries.
- Finally, heating the finished extrusions in an aging oven hardens the aluminum, making it more durable. Finishes conferring other benefits may be applied after the aging process is complete.
Direct vs. Indirect Extrusion
The exact method used to create an aluminum extrusion varies depending on a number of factors. Direct and indirect extrusion methods broadly represent the subcategories of the technique, and each poses a unique set of advantages suitable for certain manufacturing environments.
In direct extrusion—or forward extrusion—a motorized ram forces the billet through the die to achieve the final shape. While more common than other methods, direct extrusion is more energy-intensive due to the force required to release the billet from the machinery.
The main difference between direct and indirect extrusion lies in which component of the machinery moves. With indirect extrusion, the ram remains stationary and the die itself is what moves to direct the billet. This mechanism reduces friction, making indirect extrusion quicker and more energy-efficient than the alternative.
Factors That Affect Extrusion
In the extrusion process, care must be taken to control a range of factors that can affect the finished product. Changing the materials or procedures used alters the final component’s physical characteristics, which is part of why extrusion can be beneficial for such diverse applications.
Some controllable factors that alter the results may include:
- Speed of ram
- Shape of die
- Shape of billet
- Type of alloy
- Extrusion, tongue, and scrap ratios
Aluminum Extrusion Experts at Tri-State Aluminum
Aluminum extrusion is a highly desirable manufacturing technique for industries ranging from construction to energy and telecommunications. The experts at Tri-State Aluminum will work with you to determine the appropriate extrusion process for your individual specifications, ensuring that your finished pieces are precise, consistent, and of the highest quality.
For more information about how we can become your full-service aluminum component providers, please request a quote today.