Aluminium is a material with very good forming and machining possibilities. High cutting speeds, low tool wear and low tool costs are important advantages that make aluminium easy to machine. Furthermore, there are many options for electrochemical processing of the aluminium surface to produce new surface properties or apply colours. ProfilGruppen offer a complete machining and fabrication facility that gives you many opportunities for adapting an aluminium extrusion to your exact needs.
CNC is an abbreviation for Computer Numerical Control, a method of controlling machinery in the manufacturing industry, such as lathes, drills etc. with computers. The aim is to be able to manufacture complicated products rationally. CNC machines have at least three axis, X, Y and Z but can be found with up to seven axis. CNC machining is carried out in vertical or horizontal machines. Aluminium can be machining at very high speed with good tool life, little lubrication and yields excellent surface finishes. There are great opportunities for working with modular fixtures, which provides rational and effective production.
Cutting is usually carried out in circular saws and gives a finish of 3–5 Ra.
Milling takes place at a high number of revolutions and gives a finish of 1–3 Ra.
Drilling provides good results if special aluminium drills are used.
Turning with a rotating work piece is a process that provides very good finishes.
Threading with a screw cutting tool is performed both internally and externally.
Punching is often a cost-effective method that requires a certain investment in tools.
Deburring of sharp section surfaces is usually done with rotating brushes.
Aluminium is soft and flexible during manufacturing and machining but the material also develops a natural surface layer of aluminium oxide, which is very hard, second only to diamonds. This surface layer provides very good protection against wear and tear and corrosion. By strengthening the oxide surface layer through the controlled process of anodisation, the material properties can be further enhanced.
Anodisation is an electrochemical method of surface conversion. The aluminium parts are jigged and then pass through a rigorous multi-bath cleaning process. After cleaning, they are immersed in a bath of sulphuric acid at a temperature of 20°C and a DC current is passed through the material, which improves the surface layer strength by up to 3,000 times. The thickness of the anodised layer is directly determined by the immersion time and current. Finally, the aluminium parts are rinsed in a bath of deionised water in order to create a surface that is entirely free of pores.
For aestetic applications, the metal can be dyed in many different colours and long-length extrusions up to 7.5 m can be anodised in a range of UV resistant shades from natural to black. ProfilGruppens short-piece anodisation process can handle components of up to 1.6 metres. The customer can choose from an almost unlimited number of colours, which are not, however, UV resistant.
Alutin is ProfilGruppens’ unique process for converting the inert anodised surface into one which is electrically conductive. Environmentally, Alutin is better than many conventional methods, such as, for example, nickel or gold chromating. By adding tin to the anodisation process, a natural-coloured surface layer that conducts electricity is achieved. This improves earthing conditions in certain electrical devices enclosed in aluminium cases. This characteristic is particularly beneficial in applications where EMS is important, for example, the electrical and telecommunications industries. It is also a very cost effective solution by comparison.
Painting is a flexible method of providing aluminium with a durable colour or surface finish. By working closely together with co-suppliers, we offer powder coating in a wide range of colours.
An aluminium extrusion can be given the desired form through bending. One of the great advantages of this method is the ability to create a finished component from a single extrusion instead of joining together several parts. Extrusions up to seven metres long can be machined using a number of different methods. The method that is used in each individual case is determined by the size of the production run, radii, force of bending and tolerances.
Tensile bending is a method that provides great accuracy of radii and bend angle. Tensile bending is a CNC controlled process that is often suitable for medium-sized and large runs. Tooling investment is required for each extrusion section and there is often a great deal of opportunity for automation.
Roller-bending is suitable for components with large radii and which do not require precise form tolerances. The tooling investment is relatively low.
Stretchforming stretches the material beyond the yield point. This method provides a high degree of accuracy. Tooling and capital costs are high thus making the method relatively expensive.
Press bending is a cost-effective method for large runs and provides good accuracy. The investments in tools is relatively high and they are dedicated to each individual extrusion. Depending on the curvature, both T4 and T6 tempered materials can be used.
|Things to think about when choosing a bending method
Several different methods for joining aluminium extrusions exist, not only to each other but also to other materials. Depending on your needs, and the requirements for your application, we can offer the following methods:
Fusion welding uses heat, plus metal as a filler to join together two surfaces. The most common methods are TIG and MIG. TIG is most suitable for thin-walled materials and provides fine weld joints. MIG is used for welding thicker materials, has a higher welding speed but a worse finish at the weld joints.
Cold press welding
Cold press welding joins together two pieces of aluminium without either heat or metal being added to the process. The joint is achieved when the specially formed seam areas of the profile are pressed together under high pressure and movement. This unites the atoms in the two pieces with a durable joint.
Bonding can be compared to soldering or welding but uses plastic instead of metal as an additive. Common types of glue are one and two-component epoxy and polyurethane adhesive. As there are many different types of alternative bonding methods, it is extremely important to thoroughly consider the best alternative for each application.
Soldering is suitable for thin product sizes, small details and when joining with other metals.
Riveting is carried out in the form of blind riveting or Tog-LLoc. Blind riveting is the most common method and is carried out without a holding-up tool. Tog-L-Loc is carried out without the addition of other material and is done with the help of a support tool.
Screw joints are most often used where it has to be possible to dismantle the joint. Usually a thread-cutting, hot-galvanised slotted screw is used.