Detection method of cylindrical shaft bending Tester

1. Scope and description

This method is applicable to the evaluation of the resistance of single-coat and multi-coat systems of paints and varnishes to cracking or peeling from metal substrates when they are bent around a cylindrical axis under standard conditions .

2. Instruments and Materials

(1) Bending Tester - one is the hinge type, as shown in Figure 1-4-22, there is a fixed hinge connected to each other

The axis of the column, the diameter of the axis is 2mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm,

16mm, 20mm, 25mm and 32mm, a total of 12 shaft rods. The gap between the shaft surface and the hinge seat plate is (0.55±

0.05)mm, the shaft can rotate freely in the shaft seat, and the instrument is equipped with a retaining bar to ensure that when the test plate is bent, the two parts

are parallel. The instrument is suitable for test panels with a thickness of less than 0.3mm.

The other is the lever type, as shown in Figure 1-4-23, the shaft rod diameter is also from 2 to 32mm, a total of 12 shafts, suitable for thick

A test plate with a thickness of 1 mm. When testing, push the handle to bend the test plate 180°.

(2) 10x magnifying glass.

3. Measurement method

(1) When testing, open the instrument completely, insert the test panel, and make the painted surface face the seat plate, close the instrument smoothly within 1~2s, and make the test panel bend 180° on the axis, as shown in Figure 1-4 -24 shown.

(2) After bending, check directly on the instrument or use a 10 times magnifying glass to see if the paint film is cracked or peeled off ( the coating less than 10mm from the edge of the test panel is not counted). If a magnifying glass is used, it should be noted in the report.

4. Result presentation

Expressed in the diameter of the shaft that first cracks or peels off the paint film. If the smallest diameter mandrel does not fail the film, record that the film does not fail when bent on the smallest diameter mandrel.

5. Reference standard

National standard GB/T 6742 "Bending test of paint film (cylindrical shaft)".