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Extruded Aluminum Bar vs Cold Finished Aluminum Bar – What’s the Difference

Are you in the market for an aluminum bar but unsure of whether to pick extruded or cold finished? If so, you’ve come to the right place. Both kinds of bars offer a range of benefits depending on your application, and we’ll explore what makes them each unique. By the end of this post, you’ll be better informed about what kind of aluminum bar is best suited for your project.

What is Extruded Aluminum?

Extrusion, whether aluminum or other, is the process of transforming the material into a cross-sectional bar by forcing it through a die. While there are several steps to the process, it is quite simple. First, a manufacturer or designer must create a die to produce the extruded bar’s final outer dimension.

The completed die is inserted into an extrusion press, and the aluminum billet of the desired alloy is heated to the required temperature, causing the aluminum to become malleable. The aluminum is then forced through the die by the press, resulting in a consistently shaped lineal length of aluminum coming out the other side.

After cooling, the extruded piece is stress relieved and cut to the desired length. The aluminum can now be heat treated and undergo other post-production operations. Because the process takes place at a high temperature, up to 75% of aluminum’s melting point, less pressure is required to force the metal through the die. This means that it is more rapid than cold forming processes.

What Is Cold-Finished Aluminum?

Extrusion is typically performed at high temperatures because the aluminum is easier to form, whereas cold finishing is performed at room temperature. Cold finishing results in extremely close outer diameter tolerances. Drawing is the most common type of cold finishing.

A die is also used in the production of aluminum bars to reduce the material diameter. The smaller diameter end of the bar is placed through the draw die, and grippers are used to pull the bar through. While drawing can be done at higher temperatures, it is usually done at room temperature.

Difference between Extruded and Cold Finished Aluminum

The primary advantage of standard aluminum extrusions is that it is much easier to work with aluminum at higher temperatures. This translates to faster production speeds, which is why an extruded bar is typically less expensive than the cold finished product. Shorter lead times to market result from faster production.

Cold finished production produces tighter dimensional tolerances, which is advantageous when using the close-fitting collets found in today’s high-speed precision CNC machining centers. It also improves the mechanical and physical properties of the material, increasing machinability and producing smaller chips during machining that break away from the cutting tool’s work area faster.

Uses of Extruded and Cold Finished Aluminum

While extruded aluminum is widely used in a variety of applications, it is not suitable for all. Any requirement for enhanced properties may lead to the use of the cold finished product as a raw material. Cold finished bar is frequently specified in aerospace and defense products requiring high strength, as well as a variety of automotive applications. Alloys used in cold finished applications include 2011, 2024, 6061, and 7075.  Aluminum alloys commonly used in extrusions include 1100, 3003, 6061, 6063, and 6101. The most common is probably 6061, which is valued for its beneficial properties.

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