Made of rubber insulation materials, the upper and lower surfaces of the insulation sheet should not have any harmful irregularities. The harmful irregularity of insulation pads refers to one of the following characteristics, namely, defects that disrupt uniformity and smooth surface contours, such as small holes, cracks, local protrusions, incisions, inclusions of conductive foreign objects, creases, gaps, concave and convex ripples, and casting marks. Harmless irregularity refers to the surface irregularity formed during the production process.
More than 5 different points should be randomly selected on the entire insulation sheet for thickness measurement and inspection. Micrometers or instruments of the same accuracy can be used for measurement. The accuracy of the micrometer should be within 0.02mm, the diameter of the measuring drill should be 6mm, and the diameter of the flat presser foot should be (3.17 ± 0.25) mm. The presser foot should be able to apply a pressure of (0.83 ± 0.03) N, and the insulation pad should be placed flat to ensure a smooth measurement between the micrometer measurements.
