Production of Aluminum

There are three steps in the primary aluminum production. They consist of bauxite mining, alumina production and electrolysis. Primary aluminum is produced in reduction plants where pure aluminum is extracted from alumina through the Hall-Héroult process. The reduction of alumina into liquid aluminum is operated at around 950° C in a fluorinated bath under a high intensity electrical current. This process takes place in electrolytic cells where carbon cathodes form the bottom of the pot and act as the negative electrode.

 

Hot Rolling

In terms of rolling aluminum, it is first sent through a hot rolling mill and then transferred to a cold rolling mill. You can produce many different types of cold rolled products. Some examples include single stand, 3 stands and 5 stands. The thickness for these can go as low as .05mm. Speeds vary, but modern cold mills reach speeds as high as 3000m per minute. There are multiple factors that affect the type of products for cold rolling. They include the type of alloy used, the rolling deformation, thermal treatment and adjustments to the mechanics and chemistry of the process.

Ingot and strip temperatures are used to control speed and reduction during the procedure. A hotter ingot needs to be processed slower in order to ensure that the aluminum doesn’t overheat.  On the other hand, a colder ingot needs to be processed at a faster in order to generate more heat.  Overall, hot rolling deals with thicker material.

Cold Rolling reduces the aluminum to tight tolerances. It is cold so that it can make the metal hard. If the metal is heated it will cause thermal expansion which may affect the dimensions of the strip. The heat can also soften the metal. Overall, cold rolling deals with thinner material.

 

Common Types of Aluminum

2024 - Very common aerospace grade that makes up wing assemblies and fuselage parts for airplanes.

6061 - Known in the industry as tool grade aluminum used for highly machined parts for all types of aluminum applications.

7075 - High strength corrosion resistant material used in aerospace applications such as beam parts, keel assemblies and wing panels.

1060 - Pure aluminum (99.5%) used in heat exchange applications, electrical conductivity, as well as medical and chemical instrumentation. Can be cold drawn and formed.

4032 - A highly wear resistant grade of aluminum with low thermal expansion used in piston brake cylinders and bearing applications.

5000 Series - Al-Mg alloys; Non-heat treatable alloys containing magnesium as the major alloying element.