Aluminium and Anodisation

Aluminium and Anodisation

Aluminium (or aluminum) is the most plentiful metal in the Earth’s crust as well as being the third most abundant element on the planet. The metal is remarkable for its ability to resist corrosion and for its low density. In modern life it is widely used by the aerospace industry and is extremely important in other areas of transportation and building.

Bang & Olufsen is famous for using aluminium widely in the manufacture of its products. Many of its earlier loudspeakers - including the Beovox CX50 and CX100 - were made from aluminium instead of wood, although the company’s use of aluminium for hi-fi cabinets actually stems from the 1960s. So what benefits does aluminium have over other types of materials?

  • Strength

Pure aluminium is soft enough to carve but mixed with small amounts of other metals to form alloys, it can provide the strength of steel, with only 33% of the weight

  • Durability

Aluminium sprayed on a polymer forms a thin insulating sheet which can help insulation

  • Flexibility

The metal may be easily shaped by any of the main industrial metalworking processes - rolling, extrusion, forging and casting

  • Impermeability

Aluminium has excellent barrier functions which makes it ideal for food and drink packaging and containers. It keeps out air, light and microorganisms while preserving the contents inside

  • Lightweight

Aluminium can be used in transport reducing the weight of vehicles, giving greater fuel efficiency, reducing energy consumption and greenhouse gas emissions

  • Corrosion-resistant

The metal’s natural coating of aluminium oxide provides a highly effective barrier to the ravages of air, temperature, moisture and chemical attacks, making it ideal for construction and manufacturing purposes

  • Recyclable

Once manufactured into products, aluminium may be recycled again and again using only a very small fraction of the energy required to make ‘new’ metal. Recycling saves about 95% of the energy required for primary production

  • Other uses

Aluminium is a superb conductor of electricity which has allowed it to replace copper in many electrical applications. It is also non-magnetic and non-combustible, properties invaluable in advanced industries such as electronics or in offshore structures

Mastering aluminium

For Bang & Olufsen, the benefits of using aluminium are almost limitless. As a manufacturing material it is flexible, durable and lightweight, as well as being environmentally-friendly and 100% recyclable.

For many years, products from Bang & Olufsen have been characterised by the use aluminium in a multitude of different ways. During the 1960s, Bang & Olufsen began using aluminium in the production of audio receivers, which at that time was quite revolutionary. The ideas of the past were discarded and products were created which addressed the customer even before they were plugged into the mains.

Bang & Olufsen’s skills with aluminium surface treatment have now developed to the point where they are unparalleled in the industry.

During the 1990s the use of aluminium for loudspeaker cabinets increased greatly as the metal was particularly well-suited for loudspeaker cabinets.

  • It is light, but offers an impressive stiffness despite a thickness of only a few millimetres. And if you shape it in one piece, you eliminate problems of dissonance from joints and corners, which are characteristic of wooden cabinets
  • The use of curved shapes avoids internal parallel surfaces which helps eliminate trouble with standing waves inside the cabinet
  • It is a ‘dead’ material causing no distortion of the sound
  • Thanks to Bang & Olufsen’s competence in aluminium processing the company is able to polish and dye cabinets in many different colour finishes
  • One of the unique benefits of using polished aluminium for loudspeaker cabinets is that the surroundings are mirrored in it, meaning that no matter where the users chooses to place the loudspeaker, it will assimilate the colours of the surroundings
  • A less known fact is that Bang & Olufsen’s aluminium finishing skills also attract car manufacturers and other lines of business to Bang & Olufsen’s factory in Struer, Denmark
  • Aluminium also plays a vital role in Bang & Olufsen’s own unique automotive sound systems, as it is used for the elegantly shaped loudspeaker grills and the acoustic lenses in Audi, Aston Martin and Mercedes-AMG cars.

Specialists in anodising

One of the specialist skills refined by Bang & Olufsen is the surface treatment of aluminium. Anodising is an electrochemical treatment of the aluminium which creates a very durable oxide on the surface. The anodising will protect the beautifully-designed surfaces for many decades and resembles the glazing on porcelain.

The anodising process was introduced in Bang & Olufsen as early as the 1950s and large dominating surfaces in natural coloured aluminium were first seen in 1964. The current (2010) anodising facility is still the most modern plant in the world today. It has 50 baths and is 50m long. Each tank contains 3.800 litres and transport between the baths is handled by three portal robots on a rail in the ceiling. The equipment is manufactured by Galvatek of Finland.

Today anodising has replaced all the earlier heavy metal polluting galvanising processes at Bang & Olufsen. The company no longer uses chromium, nickel, cadmium or zinc.

Bang & Olufsen is able to make use of the countless possibilities offered by the mechanical and chemical surface treatment of aluminium to create the exact surface finish specified by its designers, including brushing to produce an attractive grain, or polishing to make mirror-like surfaces, using natural diamonds in the cutting process. Finally, the company uses a milling process to form edges, openings and functionalities in the aluminium plates and profiles. The removed aluminium is then recycled. Milling of items with surface finishes like grinding, polishing and so on can be complex as the surfaces are easily scratched during the milling process. The surface is therefore either protected with plastic coatings or pre-anodised.

Adapted from the Bang & Olufsen Newsletter February 2010

Anodisation facilities

Anodisation facilities

Anodisation facilities

^ Shown above are Bang & Olufsen’s anodising facilities in Factory 5, Struer, Denmark

YouTube Preview Image

This page is also filed under anodized aluminum (for US readers)

  • Share/Bookmark