Aluminium
The metal aluminium as we know it in its daily use and in its industrial applications, is a fantastic material that has unlimited applications. The element aluminium is, after oxygen and silicon, the most widespread element on earth. About 8.5% of our earth’s crust consists of aluminium, however always in combination with oxygen as AI2O3. This is mostly the case in Bauxite which contains an average of 55% aluminium oxide. The name bauxite comes from the town Les Baux in the south of France where this ore was found for the first time. Important working areas for bauxite are now Brazil and Australia. Australia is the biggest supplier of aluminium oxide, also called ‘alumina’. One needs about 4 kg of bauxite for the production of 1 kg new aluminium. The mining of bauxite is done with the so-called opencast mining. The alumina is transported by ship to the companies that convert this ore into new aluminium. The primary process, the so-called electrolysis, always takes place near a sufficient number of energy sources. The liquid aluminium that is the result of this electrolysis, is then brought to a casting house. There it is cleaned and mixed with other components after which the whole is casted in slabs or billets. The billets are then used to make aluminium profiles with the aid of extrusion. Read more about this process in the chapter Extrusion.
Extrusion
When extruding the aluminium profiles, a part of an aluminium billet is pressed with great force through a metal die. The die’s openings allow the required aluminium profile to be created. The complexity and feasibility of a profile depends mainly on the size of the profile (the circumscribed circle), the number of hollow spaces in the profile, the aluminium alloy (e.g. EN AW 6060, 6063, 6082, 6005, 7020 etc.) and the required surface quality (decorative, industrial). When the profiles come out of the extrusion press, they undergo various treatments such as cooling, stretching, sawing, stress relieving treatment and wrapping. A surface treatment often follows, as the final application of an aluminium profile often also serves an optical purpose. This happens mostly by anodising or powder coating the profile. When anodising, an aluminium oxide skin is applied in an electrolytic way which ensures a natural hard and wear-resistant surface. Moreover, it gives the aluminium a nice, uniform and matt colour. Various lacquering techniques are available for the lacquering process, powder coating being the most common one. During this process, electrically charged particles of epoxy- or polyester powder are applied to the aluminium. Then, the whole is put into an oven where the powder melts and so ensures a smooth and wear-resistant skin on the aluminium. Nearly all desired colours and metallics are available. Earlier in the text, the extrusion, anodising and coating of aluminium profiles have only been explained briefly. Please contact our employees, should you be interested in more detailed technical information. One or more finishings, mostly machining, will nearly always follow, as an extruded, anodised or lacquered profile will hardly ever be used in this – unmachined – form. These processes are described in the chapter Aluminium Machining.
Aluminium Machining
The mechanical machining of aluminium profiles or castings can take place with, for example:
| Sawing |
Punching |
Brushing |
Deburring |
| Welding |
Grinding |
Engraving |
Glueing |
| Milling |
Drilling |
Honing |
Cutting |
| Blasting |
Turning |
Polishing |
Bending |
The machining of aluminium requires, in general, tools that are specifically suitable for working on aluminium. In general, tools that are also used for other metals, are not suitable for the machining of aluminium. It is important to keep these tools separate in a production area. For machining tools, the alloy to be shaped is often the criterium for the cutting tools to be used. Moulding alloys require a different cutting tool than extrusion alloys do. One can consult tables for the correct tools. These tables indicate e.g. the joining, cutting speeds, shaping angle, cutting angle and clearance per alloy. Moreover, the use of the correct coolant and lubricant is an important factor. Aluminium is, in general, easier to shape than steel as it is much softer. About 2 to 3 times less capacity is needed when shaping aluminium compared to steel with a comparable strength. The good machinability however also entails special problems, such as the difficulty in breaking fragments due to the great toughness and the strong ‘sticking’ of aluminium particles on the cutting tools. But also the stretching of aluminium products demands more attention due to the limited hardness. Special stretching tools are therefore often needed for the machining of aluminium profiles. ALUDEX mostly uses CNC-controlled machining centres for the milling, drilling, cutting and sawing of aluminium profiles and casting. Several 5-axis CNC machines are the show-pieces of our machinery, by which profiles up to a length of 9 meters can be processed on 6 sides in one go.
Casting, Steel and Non-Ferrous metals
Besides the core-business of ALUDEX, the delivery and machining of aluminium profiles, we also ensure the machining of casting, (refined) metals and non-ferrous metal parts for our customers. So also for the CNC-machining of non-aluminium parts and for “conventional metal machining”, ALUDEX is the right address!
We'd be glad to take on your machining ‘challenge’.
Please do not hesitate to contact us!
