Anodising technology • Energy systems
Microelectronics • System software

Anodising guide - 4. Anodising on your own

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Now we come to the practical part, where we show you how to anodise and color aluminum quite simple. The results are impressive and are - if you take care - at least as good as in industry.

Because of the sometimes harsh chemicals, gases and vapors, you should perform all steps in a ventilated and insensitive room.

4.1  What can be anodised?

How well a piece can be anodised depends mainly on the used alloy. Pure aluminum is the best, but due to its softness is rarely used as material. The most common alloy for anodizing is AlMgSi0,5. Aluminum-silicon alloys with high silicon content are known for their very good castability and often also build good anodized layers - but these have a dark discoloration and are therefore not suitable for bright colors. A list of the most common aluminum alloys and their anodising and staining qualities can be found in our download area.
In principle: the purer the aluminum is present in the alloy, the better it can be anodized - and unfortunately the more worse it is for machining processes (drilling, milling). The distinction of the various alloys is difficult for the layman, but here are some hints:

Furthermore, the surface of the workpiece plays an important role. When you cast parts, for example, you often get rough, porous, and sometimes cracked surfaces. By appropriate mechanical and chemical treatment such defects at least can be mitigated.
May be your profiles could be already anodised - please verify this before. An existing anodisation has to be removed by etching or mechanically before re-anodising!

In any case, with any new alloy you should do a trial with a piece of scrap!

During anodizing the workpiece becomes slightly larger due to the layer formation. Depending on the thickness produced 0.005 to 0.03mm are possible. Therefore in case of perfectly fitting parts this growth must be included. Threads, however, are not critical because of the relatively large backlash.

4.2  What do I need?

The necessary chemicals and materials should be available anywhere at a fair price. If you have problems in obtaining: all chemicals you need to anodizing you get in the pharmacy (of course some things are more expensive there). Below you find a list of quantities for first attempts:

Last Updated: Monday, 08 February 2016 14:28