1、 Scope of application of cup protrusion tester for paint and varnish coatings
The lightweight coating cupping tester designed and manufactured according to the international standard ISO1520 and the national standard GB9753-88 is suitable for evaluating the resistance to cracking or separation from metal substrates of coatings (single-layer or matching system coatings) of paints, varnishes, and related products. It is used to conduct indentation tests under the standard specified experimental methods to gradually deform the coatings and evaluate whether the coatings pass or fail. The indentation depth can also be gradually increased to determine the minimum depth at which the coating begins to crack or detach from the substrate.
2、 Technical specifications of cup protrusion tester for paint and varnish coatings
1. Compression diameter: 20mm
2. Maximum depth of indentation: 10mm
3. Compression accuracy: 0.05mm
4. Digital division value: 0.01mm
5. Maximum indentation force: 1000N
6. Test piece specifications: 70mm * 70mm * 0.3mm~1.25mm

3、 Experimental procedures and operating methods
1. Preparation of test pieces
(1) The test piece is square in shape, with dimensions ranging from 70mm * 70mm * 0.3mm to 1.25mm
(2) The material of the test piece should be polished steel plate and meet the requirements of GB9271. The test piece should be flat without deformation.
(3) Prepare the coating on the test piece according to the standard requirements, dry it, and measure its thickness. The test can only be conducted after adjusting the state for at least 16 hours in an environment with a temperature of 23 ± 2 ° C and a relative humidity of 50 ± 5%.
2. Operation method
(1) Test of single-sided coated board: - Automatic zeroing
Rotate the handwheel of the testing machine in the downward direction (clockwise direction) to the bottom, loosen the clamping device on the upper test piece of the testing machine, insert the single-sided coated test plate with the metal side facing down and the coating side facing up into the gap on the upper part of the testing machine, align the punch with the central axis of the test piece, and tighten the clamping device. Press the red reset button on the instrument panel, and the display will show zero. Rotate the handwheel in the upward direction (counterclockwise direction) at a speed of 0.2 ± 0.1mm/s (i.e. 2-3 seconds per turn). When the reading reaches around 0.40mm, the punch touches the metal surface of the test plate, and the display automatically shows the zero point. At this time, the red light of the instrument is on. Continuing to rotate the handwheel, the display reading will be the rising height, which is the depth of indentation. It cannot be reversed during operation, otherwise the reading will be inaccurate.
(2) Test of double-sided coated board - manual zeroing
Rotate the handwheel of the testing machine in the downward direction (clockwise direction) to the bottom, loosen the clamping device of the upper test piece of the testing machine, insert a random zeroing steel plate into the gap of the upper part of the testing machine, and tighten the clamping device. Press the red button on the instrument panel to make the display show zero. Rotate the handwheel in an upward direction (counterclockwise) and slow down when the reading approaches 1.80mm. When the red light of the instrument is on, that is, when the display is zero, stop turning the handwheel. Release the clamping device and manually reset it (press the red button on the instrument panel). Rotate the handwheel in the upward direction at a speed of 0.2 ± 0.1mm/s, and the display will read the upward height, which is the depth of indentation.
(3) Check whether the coating on the test piece cracks or separates from the substrate with corrected vision or a 10x magnifying glass.
(4) The above procedure should be performed on two separate test pieces. If the results are different, additional tests should be conducted until the results of the two test pieces are consistent. If cracks appear on the substrate, the experimental results are invalid.
3. Paint and varnish coating cupping tester to determine the minimum degree of damage caused
(1) When the coating on the test piece cracks for the first time or separates from the substrate, the punch stops moving (the number on the display is the depth of advance). The above test needs to be repeated on the same substrate to verify the results until they are consistent.