We use the Erichsen test to check the deformation ability of powder lacquer coatings under permanent load. We perform deep-drawing on sample plates with standard size and composition. Using a mechanical gauge, we press a 20 mm spherical cap in the surface of the sample plate, by turning the driving wheel at constant speed, until the first crack appear on the coating. The test result is the distance at which the spherical cap is pressed into the sample plate until the appearance of the first crack.
During the cracks, the following phenomenon can be observed on the sample plates.
This procedure is suitable for checking the coatings made on workpieces exposed to loads causing permanent deformation. We use this procedure to simulate stresses that affect the coating with a permanent stress and cause deformation in the meantime. During the procedure, we examine the maximum deformation tolerance of coatings. Such stresses appear during deep-drawing, bolt connections, bending, etc. From the test results, we can draw conclusions on the appropriateness of the baking cycle and/or the appropriate preliminary treatment of the workpieces. This measuring process is suitable only to verify the coating of fine plates or standard sample plates.