Brief Introduction of Metal Powder Coating

April 27,2022

As we all know, in the process of metal powder spraying, the powder coating is transported to the spray gun through the airflow after fluidization. The spray gun generates corona discharge at the electrode needle of the spray nozzle through the high-voltage electrostatic generator, and dense negative charges are generated near the electrode. When the powder is ejected from the gun head, the captured charge becomes charged powder. Under the action of airflow, electric field, and gravity, it flies to the grounding workpiece and adsorbs on the surface of the substrate.


metal powder coating


The coating method of metal powder coating


In most cases, the electrostatic spray gun is used for coating, because the product contains metal pigment. When using an electrostatic gun for construction, ensure good grounding of the system, and set low electrostatic voltage and power output to prevent ignition during spraying. After long-term spraying, a lot of metal powder may accumulate at the discharge needle of the spray gun, and the constructor is required to sort out the discharge needle regularly.


A gloss of metal powder coatings


In most cases, because of the large error, it is not advocated to use the gloss meter to measure the gloss of the metal appearance film but only uses the visual comparison method to judge whether it is the same as the standard sample.


Recoverability of metal powder coatings


As for the powder made by the dry mixing method, because the separation phenomenon will occur in the process of spraying and recycling, there will be a certain difference in the content of metal pigment between the recycled powder and the new powder, which may lead to the different appearance of the film and color deviation. This is due to the different properties between metal pigment and powder particles. If the powder coating made by bonding and fixing method is used, because the ratio between metal pigment and powder particles is relatively fixed, the powder can be recovered from scratch.


Gloss coating of metal powder coating


Spraying a glossy coating on the metal powder coating has the following advantages: enhancing the stone impact resistance of the metal powder coating; The aesthetic effect of adding metal powder coating; Thoroughly handling the readability of metal pigments; Improving the weather resistance of metal powder coating. To ensure the appearance of the gloss layer, the workpiece sprayed for the first time shall not be polluted. Therefore, it is generally required to have a fully automated spraying line and two sets of independent spraying rooms for separate coating. Generally, do not spray the gloss coating.


Readability of metallic pigments


Whether the powder is made by the dry mixing method or the bonding fixation method, it can not completely deal with the problem of the readability of metal pigments. The only way to deal with readability is to spray a transparent coating on the metal powder coating.


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