Squareness
Squareness refers to the degree to which the actual angles at the four corners of a steel plate deviate from a right angle. The measurement method is as follows: a perpendicular line is drawn from the vertex of one corner of the steel plate to the opposite long edge (or the extension of that long edge); the ratio of the shortest distance from the resulting foot of the perpendicular to the adjacent corner vertex-along that edge-to the width of the steel plate constitutes the squareness. This value is expressed as a percentage and generally does not exceed 10%.
Flatness
Flatness refers to the degree of unevenness on the surface of a steel plate. Generally, the distance between two adjacent crests is defined as the wavelength, and the vertical distance between the line connecting the two crests and the trough is defined as the wave height; the ratio of the wave height to the wavelength represents the degree of unevenness. Specific requirements regarding flatness must be referenced in the relevant product standards.
Camber (Sickle Bend)
Camber refers to the maximum deviation of the steel plate's edge from a straight line; it is typically measured by placing a straightedge along the concave side of the edge. According to the Chinese standard GB/709-88, this deviation must not exceed 3 mm per meter of length.