Definition and Applicable Criteria for Film Flexibility

When the paint film coated on the substrate is bent due to external force, its comprehensive properties such as elasticity, plasticity and adhesion are called flexibility. The flexibility of the coating is determined by the composition of the coating and is related to the deformation time and speed of the coating during the test.

The cylindrical shaft bend Tester is suitable for soft metal plates not larger than 1.0mm, such as aluminum or other metal plates that will not twist the shaft. Conical mandrel bend Testers can also be used for full panel testing, avoiding the discontinuity in results obtained with a conventional set of mandrels.

GB/T 1731-93 stipulates the measurement method for the flexibility of the paint film. The flexibility of the paint film is expressed by the minimum diameter of the shaft that does not damage the paint film. The compliance testing machine has 7 steel shafts of different diameters. Put the paint film upwards on the test board with both hands, press the paint film tightly on the shaft of the specified diameter, and bend the test board around the shaft within 2 to 3 seconds. After bending, the thumbs should rest on the centerline of the shaft. Use a 4x magnifying glass to observe whether the paint film has damage such as mesh, cracks, and peeling.