What is anodizing?

On this page we would like to explain to you what anodizing is and what our possibilities and unique processes are for further improving your products. Our experienced staff will be happy to tell you more if you have any questions.

Anodizing is an electrochemical process in which aluminium is converted into aluminium oxide (Al2O3) in a controlled environment. This is done with electricity and an electrolyte (sulphuric acid). By continuously dissolving aluminium, a layer is formed containing a large amount of pores. An anodized layer is hard and brittle, with properties that can be compared to glass or ceramics; the layer will also ‘break’ during strong bending.

It is a material-specific layer, with an exceptional adhesion to the substrate (aluminium). Practical anodic layers are between 5 – 60 µm, depending on alloy and application. The physical law for the anodizing process is Ohm’s law: U = I x R, or Voltage (V) = Current (A) x Resistance (Ω).

During anodizing, the resistance of the formed layer increases and influences the anodizing process / build-up speed. This is controlled by programmed process steps. Anodizing is a galvanic process, but with a reversed pole. The workpiece is connected to the anode in contrast to standard galvanic processes (such as silver plating).

Why anodizing?

Aluminium is a metal with advantages in terms of weight and (mechanical) workability. However, there are also disadvantages to aluminium that can be improved by anodizing layers, such as

  • Corrosion resistance
  • Wear-resistance
  • Optical requirements
  • Insulation and reflection
  • Adhesive layer for lacquers or glues
  • Gliding properties
  • Non-stick

What do you want to improve your products with? Please feel free to contact one of our employees, they will be happy to tell you more about the possibilities.

The advantages and disadvantages of anodizing

Anodizing provides surface-improving properties. The impact resistance, however, remains low, despite the fact that the layer is very hard but also very small in thickness. The process always results in a roughening of the surface, which is also influenced by the alloy, pre-treatment and process. Anodizing greatly increases the applicability of aluminium. The layer formed consists of ‘vertical columns’ perpendicular to the surface. Sharp corners should be avoided in order to optimally follow the contours.

What possibilities do we have with anodizing?

We have fully automated production lines that are PLC controlled and where the processes are continuously monitored. We can treat products up to a length of 3,600 mm, including all pre and post-treatments.

Mechanical pre-treatments:

  • Blasting; in-house mechanical (carrousel), glass bead via external partner
  • Drumming; de-burring and polishing technique by means of ‘stones’.
  • Belt grinding

Chemical pre-treatments:

  • Standard (dimensionally stable) pickling; products delivered in final dimensions retain their dimensions
  • Mattifying pickling; a matting of the surface provides retouching of irregularities (not dimensionally stable)
  • (medium) gloss varnish; silk gloss effect which also makes light scratches less visible (dimensionally stable is possible)

After treatments:

  • Colouring; the absorbent colour baths provide a deep black colouring, other colours are negotiable
  • Sealing; the open pore structure is compacted using hot water (96 °C) to create corrosion resistance.
  • Application of primers and/or lacquers by wet painting (for project-based applications)
  • Impregnation with polymers; see Tufram® under process group polymer layers.

Our high-quality titanium stretching technology guarantees high quality standards and efficient production.

What processes of anodizing do we offer at Mifa Surface Treatment?

  • Normal anodising
    Is mainly used for protection against corrosion and preservation of the optics. The thickness of the layer depends on the alloy and the desired properties and is in practice 5 – 25 µm.
  • Hard anodizing
    Hard anodizing of aluminium is mainly used to increase wear resistance and can be combined with polymers (Tufram® see process group polymer layers). Layer thicknesses are usually between 20 – 50 µm.
  • GlissCoat®
    This process was developed for the surface treatment of aluminium shock absorbers and combines low roughness with high wear resistance and improves the Stick-Slip effect.
  • Magoxid-Coat®
    This process was developed for surface treatment of magnesium workpieces. It is a plasma-chemical treatment based on a melt on the surface of the workpiece. The spinel-shaped layer has different properties than the anodic layers on aluminium. The black variant is extremely light-resistant. The Magoxid-Coat® process is offered by a sister company.
  • Kepla-Coat®
    Is the same process as Megoxid-Coat®, but for application on aluminium or titanium and is also offered by a sister company.

Mifa Surface Treatment is part of Mifa

Mifa produces complete aluminium extrusion profiles with tolerances from ± 0.02 mm. Precision extrusion gives designers enormous freedom of shape, without the restrictions of standard norms. This allows you to realise the optimal product.

For our customers, we offer precision extrusion, machining, surface treatment, assembly and many other techniques. We have all these techniques in-house. Curious about our factory? View the Mifa tour here: