Aluminium anodizing

Clear anodizing forms a layer of 5 to 25 µm and is used mainly for corrosion protection and a decorative appearance. Hard anodizing forms a layer of 10 to 80 µm, is considerably harder and more wear-resistant and is used for functional, mechanically stressed parts. Hard anodizing changes the shade of the part depending on the alloy, from pale grey through olive green to dark brown. If you need exact values, see the Tech. specs tab.

No. The best results come from wrought alloys of the 1000, 5000 and 6000 series (EN AW-1050, 5083, 6060, 6082, 6063). Some 7000-series alloys can be processed after consultation. Cast aluminium with a high silicon content is unsuitable for standard anodizing; for high-pressure die castings we have developed a special process (Anodizing of castings). State the alloy type in your order: for some processes the material specification of the part is essential.

The maximum dimensions are 3700 × 1700 × 800 mm and the minimum part size is 10 mm. We are among the processors with the largest capacity in Central Europe. For larger parts, contact us and we will assess the options.

Yes, and you need to allow for it in the design. The oxide layer grows in both directions from the original surface, with the outward growth making up about 50 % of the layer thickness. With a 30 µm layer, a hole diameter decreases by 2 × 15 µm = 30 µm. Also allow for increased roughness, which we cannot estimate precisely in advance as it depends on the process conditions. The surface texture (E0, E6, polishing) also affects the dimensions.

Colours: black, gold in several shades, champagne, blue, orange, red and purple. Electrolytic shades C31 to C35 (from bronze to black) have high UV stability and are suitable for outdoor use and façades. We colour black, gold, champagne, blue and orange in tanks with a net size of 3200 × 1650 × 800 mm, red in 2000 × 1100 × 500 mm and purple in 950 × 300 × 950 mm. The surface can be fine matt (E0), matt (E6) or glossy after electrochemical polishing.

Yes, in two ways. Penetrated Teflon is hard anodizing impregnated with Teflon (PTFE 3 to 5 µm): the surface is slippery and the part’s dimensions do not change. Thermoset Teflon is a separate coating 10 to 50 µm thick, which on aluminium we apply over hard anodizing; some types are approved for food contact. You will find details in the Combined coatings and Non-stick coatings categories.

Parts must be free of oils, emulsions, pastes and swarf (especially threaded blind holes). Products based on silicones, rapeseed oil, drying oils and waxes are not permitted. Parts must not be marked with paint or markers, taped, or contain components made of metals other than aluminium. With leaking welds, residues of solutions will seep out of the gaps and impair the quality of the treatment; for hollow welded assemblies we recommend providing drainage through a technological hole. Do not pack parts in bubble wrap. You will find the full conditions in the document Conditions for the appearance and cleanliness of parts (PR 06/24).

The order and drawing documentation with the actual dimensions of the part, defined contact points and the marked visible surface; we need these to calculate the total surface area. If the contact point is not specified on the drawing, we choose it at our own discretion. State any requirement to protect holes, threads or surfaces directly in the order, not just on the drawing; masking is charged as a surcharge. We accept PDF, DWG, DXF, STEP and IGES. For every order we issue a certificate of the treatment performed; for aerospace and automotive we also issue extended quality documents on request.