GMW GMW14665 PDF

This specification covers basic requirements for anodic coatings on aluminum and aluminum alloys.

Material Description. The anodic coating is an oxide layer produced by an electrolytic oxidation process. The oxide layer provides improved corrosion protection. This coating can be transparent or colored. Anodic coatings must be either sealed or painted to maintain their appearance.

Symbols. Not applicable.

Applicability. Anodic coatings are used for:

Decorative Parts For:

Interior Applications.

Exterior Applications.

Exterior parts, whether clear or colored, are further classified for chemical resistance and application as follows:

• Class A – Extreme alkaline resistance to pH 13.5.

Recommended for vehicles in regions where chemical exposures may be severe and where post-car wash polishing to restore gloss is not desirable. Supplemental inorganic or organic coatings may be used to meet the chemical resistance requirements. The three current strategies for achieving this performance are:

Class A1: Inorganic/ceramic coating per GMW16209.

Class A2: Organic coating per GMW16929.

Class A3: No supplemental coating, performance achieved via sealing chemistry.

The surface areas to be supplementally coated (A1, A2) must be clearly defined in the engineering drawing. As these coatings may influence part appearance, the total system must be approved before usage. Note that supplemental-coated parts must pass all requirements for both the anodize (GMW14665 Class A), and for the coating (GMW16209 or 16929).

• Class B – High alkaline resistance to pH 13.0.

Recommended for vehicles in regions where chemical exposures may be less severe and where post-car wash polishing to restore gloss is acceptable.

• Class C – Alkaline resistance to pH 12.0.

This performance level may be usable in emerging markets or other areas where environments are known to be mild. It is only usable via special drawing note for parts that are not shared among other regions.

Note: If no decorative exterior class is listed on the drawing, Class B is assumed.

Exterior applications should be limited to above beltline. Applications below beltline are subject to a special release and specific requirements of a higher level must be defined. Only Class A1 and Class A2 will be considered. The corrosion severity in that area is much higher than above beltline because of copper (etc.) containing brake dust.

Exterior colored anodized parts are required to be Class A1 or A2.

Functional Parts For:

Interior Applications.

Exterior Applications including painted aluminum parts and hard anodized layers. Hard anodized coatings are characterized by their hardness and a thickness of more than 25 μm. For applications that needminor corrosion protection and also high wear protection, the hard anodic layer may not be sealed. For applications that need a very high corrosion protection, but only moderate wear protection, the hard anodic layer has to be sealed. Anodized coatings used as a paint substrate (designation FETu) are used unsealed or partially sealed (e.g.; 5 minutes in hot water) to provide the best paint adhesion.