Factors that affect the quality of powder coatings

Update:06-12-2019
Summary:

In the strict sense, powder coating is just a semi-fini […]

In the strict sense, powder coating is just a semi-finished product. For customers, it is a special raw material. It must be used by customers to form the final product-coating. Therefore, the quality of the coating is not only directly related to the quality of the powder coating, but also closely related to the quality of the coating process.

At present, there are few technical personnel specializing in powder coatings and coating services on the market. Most of the technical personnel in powder coatings companies have developed from chemical, material, paint and other professional studies, and some have been trained from the front line for a long time. Those who change careers generally lack rich theoretical and practical knowledge.

Although there are many factors influencing quality, there are usually only one or two key influencing factors on the site, so quickly eliminating interference factors to determine the influencing factors is the key to service success. The determination of influencing factors generally adopts the screening method, that is, according to the test results of the quality of the coating products, analyzes and excludes non-relevant factors, quickly locks the point-of-contact factors, and creates conditions for formulating test plans and confirming influencing factors.

If the coating adhesion is poor, as long as there is a wide range of coating adhesion (such as a coating area of ​​not less than 20cm2, a qualified workpiece is greater than or equal to one, etc.), powder coatings, phosphating agents, substrate materials and Influencing factors of spraying process.

For slightly rusted workpieces and workpieces with obvious water marks after washing, the coating adhesion will not be seriously reduced; and the problem of poor adhesion caused by insufficient curing can be checked during the cross-section test; The poor focus is mainly caused by the unqualified surface treatment of the workpiece. One is the incomplete degreasing and the other is the too loose phosphating film.

Another example is the problem of air bubbles and pinholes. As long as there are no uniform or regular air bubbles or pinholes on the surface of the workpiece after painting, the effects of powder coatings, surface treatments, substrate materials, and spray curing processes can be basically eliminated. Local treatment failure, such as local over-corrosion (corrosion voids, deposited oxides), impurities (oil spots, mud spots, rust spots), etc. Large-area uniform bubbles or pinholes are mainly caused by problems with substrates (such as castings and galvanized parts).

To find out the influencing factors, a detailed demonstration must be carried out before the test plan is formulated. A single service person must also perform a self-demonstration. From the test data, process parameters, process test results, and other information collected on site, etc., the positive factors are determined. Discrimination and analysis of the negative aspects to ensure that the initial test direction is accurate.

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