Potential savings when polishing aluminium

Polishing aluminium: Aluminium hardness determines the cost-effectiveness of the process

The dependency between the degree of hardness of different aluminium qualities and the economic efficiency of the industrial polishing process can be determined. Automotive manufacturers and their industrial polishing suppliers benefit equally from the results of the scientific analysis. This is because polishing processes become much more calculable, which means that potential savings can be identified more easily.

The hardness of aluminium profiles is influenced by the manufacturing process

The example of the automotive industry can be used for a more precise explanation: the aluminium profiles relevant here have different specifications and degrees of hardness. These are influenced by the temperature exposure during the manufacturing process. The raw material is cast and then moulded by extrusion, whereby the material is pressed through a hollow tool. The way in which the subsequent curing process is carried out determines the degree of hardness of the material. Common proof stresses (Rp02) of the alloy EN AW 6401 (Al 99.9 MgSi) are, for example, FXX (30 N/mm2), F18 (100 N/mm2) and F24 (220 N/mm2).

Specification of the aluminium influences the economic efficiency of the polishing process

Load-bearing aluminium parts on the vehicle or roof rails have higher strengths than non-load-bearing decorative parts in the interior, for example. This has an impact on the polishing process. In systematic test series with aluminium test plates from a leading manufacturer of aluminium in polishing quality, it has now been proven for the first time that a higher cutting rate and therefore faster results can be achieved with lower tensile strengths than is the case with harder qualities of the same alloy. This has a significant influence on the polishing time and therefore on the costs of the polishing process. The advantage for industrial companies is great, as significant potential savings can be identified. By systematically determining the dependence of polishing performance on the degree of hardness of the aluminium, it becomes clear what potential savings can be made by switching to an alternative specification. Furthermore, polishing pastes can be matched even more specifically to the respective specification, as it is now possible to precisely determine the different cutting rates for grinding marks or ‘orange peel’. Thanks to the knowledge gained, industrial companies can achieve the best possible surface qualities more economically.

Conclusion: For the first time, it has been possible to determine the cutting rate when polishing aluminium of different hardnesses of the same alloy. This opens up new possibilities for industrial companies to increase the efficiency of their polishing processes. For this purpose, either a change to a more favourable aluminium quality or an optimised setting of the process parameters to the aluminium specification used is recommended.