Thickness: A thickness measuring instrument with a minimum graduation value of 0.01 mm is used to measure the thickness at least 20 mm inward from the edge of the panel. These measuring points should include at least a plurality of thicknesses at the four corners and the midpoint of the four sides. The limit value error between all measured values ​​and the nominal value is taken as the test result.
Length (width): The length is on both sides of the plate width, and the width is measured on both sides of the plate length with a steel tape with a minimum graduation value of 1 mm. The limit value error between all measured values ​​of the length (width) and the nominal value is taken as the test result.
Diagonal difference: Measure and calculate the difference between the lengths of the two diagonals on the same plate with a steel tape with a minimum division value of 1 mm. The maximum of the measured differences is used as the test result.
Straightness: Place the board flat on the water platform, and use the side of the 1000 mm long steel ruler to lean against the edge of the board, and then use the feeler gauge to measure the maximum gap between the edge of the board and the side of the steel ruler. The maximum value of all the measured values ​​on each side was used as the test result.
Warpage: Place the concave surface on the water platform, use a 1000mm long steel ruler to stand on the side of the board, and measure the distance between the steel ruler and the board with a ruler with a minimum graduation of 0.5mm. Maximum gap height. The maximum value of all the measured values ​​was taken as the test result.
Aluminum thickness: The aluminum material removed from the sample was used as a test piece. The thickness of the aluminum material was measured with a thickness measuring instrument having a minimum division value of 0.001 mm (the thickness of the coating or the like should not be included). Measurements should be made in sufficient numbers, but at least four corners and five centers should be measured on each test piece. The minimum value and the arithmetic mean of all measured values ​​were used as test results.
Coating thickness: The thickness of the coating refers to the total thickness of the coating. It is tested in sufficient places on the specimen according to the provisions of GB/T4957, but at least four corners and five centers are to be measured on each specimen. The minimum value and the arithmetic mean of all measured values ​​were used as test results.
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