Everyone knows that the adhesion of aluminium alloy surface is poor. It is very difficult for direct spraying paint to have good adhesion with the surface of aluminium material. Even if it is applied reluctantly, it will soon fall off. So how to increase adhesion?

It is necessary to make a layer of primer on the aluminium alloy substrate to increase the adhesion of the paint, and then spray the finish. There are three main steps:

 Preparations and conditions before spraying:

Weather Conditions: Paint must be constructed in sunny weather. It is forbidden to construct under rainy, foggy, snowy and heavy dust conditions. The optimum temperature for spraying is about 25 C and humidity is below 80% RH.

2. Substrate treatment: Aluminum alloy substrates should be grinded and oxidized. Surface should be rust and oil removal, and ensure clean and dry without dirt, dust removal, fill, before painting, and before spraying to ensure the drying of the substrate.

3. Spraying gun standard: spraying gun with 1.5-2.0 mm caliber can be selected, and spraying gun pressure should be adjusted to 3-4 kg/cm 2. Modification of fog amplitude to medium pressure to 3-4 kg/cm

2. Spray the surface of the workpiece as wet as possible and spray it 2-3 times evenly. Properly adjusting the amount of oil, it is easy for particles to appear on the surface of paint film when the amount of oil is too small.

4. Air compressor: Before construction, air compressor and filter should remove water first to avoid pinholes in paint film.

 Primer spraying:

1. After good surface treatment effect has been achieved on the surface of aluminium alloy, epoxy zinc-rich primer special for aluminium alloy can be sprayed. The primer has good adhesion to the surface of aluminium alloy, especially the two-component epoxy zinc yellow primer. The paint has the unique high adhesion, toughness, hardness of epoxy paint, and good matching performance.

2. Mixing ratio: primer: primer curing agent: diluent = 4:1: appropriate amount. Mix the paint for 5 minutes before mixing. Use more accurate electronic scales to weigh according to the mixing proportion, so as to ensure the accurate mixing ratio. After mixing the paint, stir it with clean aluminium bars or iron bars until it is completely even. During construction, attention should be paid not to mix other kinds of paint, solvent, etc. and to keep the spraying environment clean. After mixing, it will be used up within 2H, and when the ambient temperature is over 30 C, the mixing time will be shortened.

3. In order to achieve the best effect, spraying can be done twice:

First spraying - fog spraying:

1. Viscosity - 14-16 seconds (20 degrees)

2. Spray volume - 1/2-2/3

3. Painting Pressure - 4.0-5.0 Bar

4. Distance of Spraying Tools - 25-30 cm

5. Standard Spray Full Open

6. Spraying time - slightly faster

Fog spraying was carried out on the whole in a scattered and thin way, and fused with the lower coatings initially. At the same time, confirm whether there is a shrinkage hole. If there is one, slightly increase the air pressure (6.5 bar) on the shrinkage hole and spray it centrally.

Paint to fill shrinkage hole.

Second Spraying-Primer Spraying

1. Viscosity - 14-16 seconds (20 degrees)

2. Spray volume - 2/3-3/4

3. Painting Pressure - 4.0 Bar

4. Distance of Spraying Tools - 25-30 cm

5. Standard Spray Full Open

6. Spraying time - slightly faster

Topcoat spraying:

1. Aluminum alloy paint is directly selected as topcoat. The paint is composed of imported hydroxyl acrylic resin, pigments and additives. The paint has strong adhesion on the surface of aluminium alloy, fast drying, self-drying or baking at room temperature, and has strong protective and decorative effect.

2. Spraying method:

FIRST SPRAYING-FIXED COLOUR SPRAYING

1. Viscosity - 14-16 seconds (20 degrees)

2. Spray volume - 2/3-3/4

3. Painting Pressure - 4.0 Bar

4. Distance of Spraying Tools - 25-30 cm

5. Standard Spray Full Open

6. Spraying time - slightly faster

The first spray is used to fix the color. Don't pay too much attention to the spray marks and metal stains, just spray one layer lightly to determine the color. The spraying tool should move slightly faster. Repeat spraying once.

Can solve the problem, if the color is not enough, can be sprayed according to the second method, and then a spray.

Second Spraying-Correction Spraying

1. Viscosity - 11-13 seconds (20 degrees)

2. Spray volume - 1/2-2/3

3. Painting Pressure - 4.5-5.0 Bar

4. Distance of Spraying Tools - 25-30 cm

5. Standard Spray Full Open

6. Spraying time - slightly faster

This spraying is to repair the paint spots and spraying marks left by the fixed color spraying, and to make the mechanical texture better displayed.

Safety and Environmental Protection Provisions:

This product contains flammable organic solvents. When used, it should comply with the safety rules of painting operation and technical operation specifications. At the construction site, attention should be paid to keeping away from fire sources, ventilation, fire prevention, anti-static electricity, poisoning and other protective measures.

Zhaoqing Xin Hi-Tech Co., Ltd. is a die-casting and painting processing plant in Zhaoqing. Its business scope covers Zhaoqing, Foshan and other places. The company was founded in 2010 (registration time is 2012). The company is located in the north of Jintao Industrial Park, Jinli Town, Zhaoqing City, Guangdong Province. The plant covers an area of 30 mu. The total investment is 30 million yuan and the annual output value is 150 million yuan. Main business: security accessories, automobile year matching, communication accessories, lighting accessories, furniture accessories. It has 400T-1, 280T-4, 200T-5, 180T-5 horizontal injection moulding machines, 5 vertical injection moulding machines, 40 CNC numerical control lathes, a batch of post-casting processing equipment and 2 large spraying lines. The company has a mold R&D and manufacturing department, and can develop die-casting molds for customers. The company has passed ISO 9001 (2015) certification of quality management system and ISO 1400 of environmental management system.