Precautions for metal powder spraying

       

Precautions for metal powder spraying

Abstract: As we all know, in the process of metal powder spraying, the powder coating is fluidized and transported to the spray gun through the airflow. The spray gun passes through the high-voltage electrostatic generator to produce corona discharge at the electrode needle of the nozzle, and a dense negative charge is generated near the electrode. Spout

 As we all know, in the process of metal powder spraying, the powder coating is fluidized and transported to the spray gun through the airflow. The spray gun passes through the high-voltage electrostatic generator to generate corona discharge at the electrode needle of the spray head, and a dense negative charge is generated near the electrode. When ejected, the trapped charge becomes a charged powder, which flies to the grounded workpiece under the action of airflow, electric field and its own gravity, and is adsorbed on the surface of the profile. Therefore, in our spraying process, we need to take adequate precautions.

 

1 Coating method of metal powder spraying

 

In most cases, electrostatic spray guns are used for painting. Because this type of product contains metallic pigments, when using electrostatic guns, you should ensure that the system is well grounded. At the same time, set a lower electrostatic voltage and powder output to prevent generation during spraying. Spark phenomenon. The effect of forming a coating film has a lot to do with the setting, quality or brand of the spray gun. After spraying for a long time, a large amount of metal powder may accumulate at the discharge needle of the spray gun, and the builder needs to clean the discharge needle regularly.

 

2 The gloss of metal powder coating

 

In most cases, due to the large error, it is not recommended to use the gloss meter to measure the gloss of the metal appearance coating film, and only use the visual comparison method to judge whether it is consistent with the standard sample.

 

3 Recyclability of metal powder coating

 

For powders manufactured by dry blending, separation occurs during spraying and recycling. Therefore, there will be a certain difference in metal pigment content between recycled powder and new powder, which may lead to inconsistencies in the appearance of the coating film and color cast. . This is due to the difference in properties between metallic pigments and powder particles. Experts recommend that the ratio of recycled powder to new powder is at least 1:4. If the powder coating manufactured by the bonding and fixing method is used, since the ratio between the metallic pigment and the powder particles is relatively fixed, the recycled powder can be reused.

 

Analyze the precautions for metal powder spraying

 

4 metal powder coating overcoat

 

Spraying the overcoat on the metal powder coating film has the following advantages: enhancing the stone-strike resistance of the metal powder coating film; increasing the aesthetic effect of the metal powder coating film; thoroughly solving the erasability of the metal pigment; improving the metal powder coating film The weather resistance. In order to ensure the appearance of the overcoat layer, it is required that the workpiece after the first spraying should not be polluted. Therefore, it is generally necessary to have a fully automated spraying line and two independent spray booths for separate painting. It is recommended not to spray overcoat under normal circumstances.

 

5 The erasability of metallic pigments

 

Whether it is powder made by dry blending method or adhesive fixing method, it can not completely solve the problem of the erasability of metallic pigments. The only way to solve the rub-off is to spray a transparent coating on the metal powder coating film.

 

6 Try to keep the spraying conditions as stable as possible.

 

Use the same set of spraying equipment, use the same voltage, air pressure and other parameters; try to keep the distance between the spray gun and the workpiece unchanged, and try to maintain the stability of the film thickness; ensure that the powder coating has been fully fluidized before spraying; when using recycled powder, ensure that it is recycled The ratio of powder to new powder is at least 1:4; try to avoid using metal powder coating to spray workpieces with complex shapes or deep depressions; it is recommended that multiple workpieces to be assembled together should be sprayed at the same time.

 

Environmental protection also means that human beings consciously protect natural resources and make them rationally used to prevent the natural environment from being polluted and destroyed; the polluted and destroyed environment must be comprehensively treated to create something suitable for human life and work. surroundings. Environmental protection refers to the general term for various actions taken by mankind to solve actual or potential environmental problems, coordinate the relationship between mankind and the environment, and ensure the sustainable development of the economy and society. The methods and methods include engineering technology, administrative management, legal, economic, publicity and education, etc.