Extrusion profiles

Industrial Aluminium Profiles, also called Industrial Aluminium Extrusions or Industrial Aluminium Alloy Profiles, are profiles of aluminium shaped by the process of forcing it to flow through a shaped opening in a predesigned die. The extruded material emerges as an elongated piece with the same profile as the die opening. Depending on the final application of the aluminium profile or extrusion, the alloy used in the extrusion process varies. Theses various alloys have differing properties mainly characterised by the following 6 aspects:

Hardness:

Due to the nature of aluminium many customers are concerned by the materials hardness when buying an industrial aluminium profile. Hardening of aluminium profiles is achieved by “heat treatment” as opposed to flat rolled products which generally achieve greater hardness or strength by a cold working/rolling process. It is important to note that an aluminium extrusions hardness is directly related to the chemical composition of the alloy. Alloy 7××× series contains the highest achievable hardness followed by alloy 2××× series, alloy 4××× series, alloy 6××× series, alloy 5××× series, alloy 3××× series and finally alloy 1××× series respectively.

Strength:

Strength is an important factor when considering product design. When aluminium alloy profiles are used as industrial components, the appropriate alloy should be selected according to the structural integrity required. The strength of pure aluminium (1××× series) is the lowest, while that of heat treated alloys of the 2××× series and 7××× series are the highest.

Corrosion Resistance:

Corrosion resistance of industrial aluminium profiles includes chemical corrosion and stress corrosion amongst others. Generally speaking, alloy 1××× series of pure aluminium has the best corrosion resistance, alloy 5××× series performs well, followed by alloy 3××× series and alloy 6××× series, while alloy 2××× series and alloy 7××× series are fairly poor. The type of corrosion resistance should also be determined according to the profiles application. All kinds of anti-corrosion composite materials should be used in conjunction with a high strength alloy used in a high corrosion environment.

Machinability:

Machining performance indicates how easily the profile can be machined by drilling, cutting etc. Because the formability of the extrusion is related to the temper, the strength range of various tempers should be taken into account after the aluminium alloy number is selected, and more often than not, an alloy with high strength is not so easily formed but rather easily machined. The opposite is true for alloys that are easily formed, they are generally not so easily machined. The formability of annealed material is generally the best, whereas that of the heat-treated material is the worst. On the contrary, the machinability of low-strength aluminium alloy is poor.

Weldability:

The ‘weldability’ of most aluminium alloys is generally not an issue, particularly the 5 series alloy, which is specially designed for welding. It is important to note that welding aluminium will generally compromise the strength and temper of the alloy and should only be done so by an experienced aluminium welder.

Decorative Suitability:

When industrial aluminium profiles are used in decorative instances, the surface is usually anodised, polished or powder coated. In order to obtain the appropriate color and surface texture, the decorative nature of the application should be considered. In general, good corrosion resistance alloys have good anodic treatment performance, surface treatment performance and coating performance.