How Aluminum Extruders Operate
Posted by Timothy Harvard , on Sep, 2015
Extruded aluminum is commonly found throughout the fabrication, construction, and manufacturing industries. Products made by aluminum extruders can be found in appliances, vehicles, spaceships, aircraft, computers, electronics, petrochemical and food processing plants, boats, lawn furniture and even as a structural component in commercial and residential buildings.
At first glanced what aluminum extruders do seems fairly simple and, in fact, the process itself is relatively low tech compared to some of the areas where the finished product will be used. However, to be able to create extruded aluminum to very exacting industry tolerances is not a simple process at all. It takes experience, expertise, and state of the art equipment. Further processing by precision saws also takes this same level of experience and expertise to ensure every piece cut is virtually identical to every other.
The Forming Process
All aluminum extruders use the same basic process. A large billet of aluminum is heated to between 800 and 925 degrees Fahrenheit. This hot billet or metal is then moved through a system which distributes a thin layer of smut, a black substance which will help prevent sticking in the extrusion press, to the exterior and to the dummy block.
The ram pushes on the dummy block which applies continual pressure to the heated alloy billet, forcing it through the die in the extrusion press. This forces the heated aluminum to form to the die and to move through the die as an exact replica of the shape.
Cooling of the die can be completed in different ways based on the different alloys and the system used by aluminum extruders. Often it is liquid nitrogen which is used to cool the die and also to prevent the formation of oxide on the aluminum alloy. If gas is used, there is no cooling involved, but there is still the elimination of oxygen in the atmosphere to prevent oxidation.
The Cooling Process
Then, depending on the specific alloy, the aluminum extruders will use a puller to keep the extrusion moving out and onto a very long table. Fans can be used for air cooling which water can also be used in the process, which is correctly known as quenching.
At specific lengths the aluminum extruders will cut the extrusion and then move it to a cooling area or cooling table. From here the extrusion is stretched to both relieve any internal tension as well as to straighten the extrusion. It is then further cut into pre-set lengths and aged in ovens to harden the alloy.
Different aluminum extruders may work to different tolerances for their extrusions as well as for their precision cutting. This information will be provided within the specs for the particular aluminum product.
At Howard Precision Metals, we work with the top aluminum extruders offering the best aluminum plate and bar available. To see our inventory and the brands we carry go to www.howardprecision.com.