What is the Cupping test?

In addition to the various properties of general coatings, coil materials also need to undergo post-processing such as deep drawing, bending, drilling, and occlusion, so the requirements for flexibility are higher than those of traditional coatings. The main indicators are cupping, impact, T-bend, adhesion and so on. The cupping test evaluates the resistance of coatings of paints, varnishes and related products to cracking or separation from the metal substrate after gradual deformation under standard conditions.

The measuring instrument for the cupping test is the cupping Tester (Figure 4-15). During the test, the cupping Tester pushes the punch out from the back of the sample at a constant speed and punches it to a specified depth to observe whether the coating is cracked or not. Fall off from the substrate to evaluate the ability of the coating to resist cracking; or push the punch out from the back of the scribed part of the sample at a constant speed, punch to the specified depth, stick it on the scribed part with transparent tape and tear it off, and pass the coating The cross-hatch adhesion after gradual deformation of the coating is evaluated by the peeled off area of ​​the coating.