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how aluminum profiles are made?

Aluminum profiles are produced through the process of extrusion. Every profile has to be designed first. During design, the function of the profile, its dimensions, shapes and material specifications are documented. Other factors such as durability, machinability and finishing are also considered. After the design has been completed on the computer, a steel die that can produce the design must be produced. With a hydraulic press, a billet is pushed through the die to form the desired profile. Herebelow are some details about the aluminum extrusion process:

Extrusion Billets

An extrusion billet may be in form of a solid or hollow cylindrical shape. Most billets are cast in an electric arc furnace with aluminum scraps. Billets are cut into an appropriate size for the length of the required profile.

The billet size may vary, with most lengths ranging from 25 inches to 72 inches. The external diameter may range from 3 to 33 inches, with 7 to 10 inches being the most commonly used diameter.

Pre-heating of the Billet

The billet and the extrusion die are pre-heated before the extrusion begins. Pre-heating the billet softens it so that it can be forced through the die. Care is taken not to heat it up to the melting point of aluminum, which is about 1,200 degrees Fahrenheit. Normally, the billet is usually heated to about 900 degrees Fahrenheit.

Direct Extrusion

The real extrusion process starts as soon as the ram starts putting pressure on the billet. The hydraulic press in the extrusion machine can exert up to 15,000 tons of pressure on the billet and die. The larger the pressure, the greater the extrusion, it can produce.

When the extrusion press applies the initial pressure, it crushes the billet against the die. The die gets shorter and becomes wider till it can no longer expand due to its restriction by the container wall. Then the aluminum starts to force its way through the orifice of the die to come out at the other side with the formed profile.

The length of extruded profile depends on the size of the billet and the opening of the die. An extrusion that is along as 200 feet may be produced with a single stroke of the press. A runout conveyor supports the formed extrusion as it comes out of the extrusion press. As the extruded profile comes out, it may be passed into a cooling bath immediately depending on the alloy. Cooling may be done with water or air. This is a vital step to ensure that enough metallurgical properties are retained in the metal. After cooling, a stretcher can be used to stretch the profiles and straighten any twisted parts.

Cutting and Packaging

If no special finish operations such as anodizing are required for special surface treatment, the profiles may be cut into shorter lengths. Typical lengths could be between 12 to 22 feet. Special devices may be used to clamp the profiles, cut them and then transfer them to a conveyor.

Aging

To achieve maximum strength, the extruded profiles are passed through a process of aging. While natural aging can take place at room temperature. Artificial aging occurs in an aging oven. The aging process is designed to ensure that there is even precipitation of fine particles through the metal. This will allow the metal to attain its full strength, hardness and elasticity.

Packing of Aluminum Profiles

After the aging has been completed, the profiles are carried to other parts of the plant for fabrication or packaging. Then they are prepared to be shipped to the customer.

Those are the basic stages involved in the production of aluminum profiles. Profiles that require special finishing or surface treatment will have to go through additional processing steps before aging and packaging.