Metal Surface Treatment Processes

Surface treatment is the surface protection technology which changes the surface of the matrix material’s mechanical, physical and chemical properties so as to improve the product’s property, such as corrosion resistance and wear resistance in the early days. The traditional surface treatment methods include galvanizing, electrophoresis, bluing, blackening, passivation, phosphating, spraying, coloring, baking finish, infiltration and shot blasting. At present, we have developed various surface treatment processes applied in surface decorations of metal, glass, plastic and other materials or other special functional required surface processing technologies, which help achieve excellent performance in many aspects such as products’ corrosion, appearance, texture, functions, etc. The detailed information is as the following.

 

Appearance

Colors, patterns, logos and gloss \ lines (3D, 2D) 

Texture

Feel, roughness, service lives (quality), streamlines, etc.

Functions

Hardening, anti-fingerprint and scratch resistance

 

Detailed information about surface treatment processes of metal, plastic and glass

1. Anodizing

Anodizing is mainly applied to surface treatment of aluminum, which uses electrochemical principles to form a layer of aluminium oxide film on surfaces of aluminium and aluminium alloys. The oxide film has special features of being protective, decorative, insulative, wear resistant, etc.

 

Processes of monochrome or gradient colors

Polishing, sandblasting or wire drawing, degreasing, anodizing, neutralizing, dyeing, hole sealing and drying
 

Processes of bicolours

① Polishing, sandblasting or wire drawing, degreasing, masking, 1st anodization, 2 nd  anodization, hole sealing and drying

② Polishing, sandblasting or wire drawing, degreasing, 1st anodization, laser etching, 2 nd  anodization, hole sealing and drying

 

Technical features

1. Improve strength.

2. Make metal parts have any color besides white.

3. Complete hole sealing without nickel and meet requirements of nickel-free for America, European and other countries.

 

Technical difficulties and the key points of improvement 

The passing rates of anodizing are related to costs of final products, and key points of improving the passing rates of anodizing are to have moderate amounts of oxidizing agents, suitable temperatures and electric current densities. This requires structure manufacturers to continue to explore and seek a breakthrough in the production process.

 

2. Electrophoreses   

Electrophoreses are used for stainless steel, aluminum alloys, etc., which can make products have various colors; maintain metal luster; improve surface properties and have good anti-corrosion performance.

Processes: preprocessing, electrophoreses and drying

Advantages

1. Electrophoreses can make metal parts have rich colors.

2. Electrophoreses can make metal parts have no metal texture and can have sand blasting, polishing, wire drawing and other treatment.

3. Electrophoreses can make metal parts have surface treatment of the complex structure in the liquid environment.

4. Electrophoresis processes are mature and can make metal parts have mass production.
 

Disadvantages

Electrophoreses have poor performance in covering defects of metal parts and die castings should have high requirements of preprocessing before having electrophoresis treatment.