Anodizing Line

Selection criteria

Bath temperature, current density, sealing quality.

Supply chain

Anodizing lines are built and run mainly by Chinese surface-treatment companies, often clustered near extrusion centres such as Foshan. Specify film thickness, colour and sealing tests in the drawing.

Buyer FAQ

What anodic film thickness should I specify for motor housings?

Indoor decorative parts usually need 5–10 µm, motor housings commonly 10–15 µm, and outdoor exposure 15–25 µm (classes AA15–AA25 in ISO 7599). Hard anodizing at 25–60 µm is for wear surfaces. Measure film thickness with an eddy-current gauge (ISO 2360) and state the minimum local value on the drawing.

How is sealing quality tested?

Common tests are the dye-spot test (ISO 2143), the acid-dissolution mass-loss test (ISO 3210, typically 30 mg/dm² or less) and the admittance test (ISO 2931). Poor sealing leads to staining, fingerprints and early corrosion, so include at least one of these tests in the drawing or purchase spec.

Why do some aluminium parts anodize badly or vary in colour?

Alloy matters most: 6063 extrusions anodize well, while high-silicon die-cast alloys such as ADC12 give a patchy grey film with poor protection. Colour also varies between alloy batches and with bath temperature and current density, so agree physical colour limit samples. Mask threads and electrical grounding points that must stay conductive.

Where it is used