a) The purpose of cast iron square box: It is a hollow cube made of cast iron or steel with six specific working faces. One of the working faces has a V-shaped groove, which needs to be calibrated under normal temperature and humidity conditions. In addition to calibrating flatness, the accuracy also needs to be calibrated for contact spots using coloring method. The number of spots in any square with a side length of 25mm is: no less than 25 points for level 1 and level 2; Level 3 should not be less than 20 points.

b) The cast iron square box requires that all working surfaces must be free of rust, scratches, cracks, dents, and other defects that affect the metrological performance. Non working surfaces should be sandblasted, painted, and chamfered. There should be signs on the inner wall of the square box, indicating specifications, dimensions, grade, factory number, and manufacturer name.

c) The cast iron square box series products include square boxes, square box workbenches, T-shaped groove square boxes, square box pads, marking square boxes, special-shaped square boxes, and inspection square boxes, mainly used for checking and marking the parallelism, perpendicularity, and other aspects of components.

d) The specifications of cast iron square boxes can be customized according to user needs, and our company can provide design drawings.

Square box inspection method: For square boxes with a side length of 315mm or less, 1mm measuring blocks are placed at each end of the inspected surface of the square box during inspection. A straight edge shaped ruler is placed on the working surface of the measuring block, and then a measuring block is used to test the plug at each inspection point. The difference between the size of the measuring block group just inserted and the size of the measuring blocks at both ends is the deviation between the two ends of the inspected point. This verification should also be conducted on several sections of the square box working face in the longitudinal, transverse, and diagonal directions. When the error directions of the straight lines measured at various positions are consistent, take the larger value. When the error directions are not consistent, take the sum of the positive and negative differences to obtain the flatness of the inspected surface plane.

Square box accuracy: For scraping square boxes, in addition to checking the flatness, the contact spot should also be checked using the coloring method. The number of spots in any square with a side length of 25mm is: no less than 25 points for level 1 and level 2; Level 3 should not be less than 20 points.