The main body of the Hebei Beizhong test equipment base iron base plate is made of high-quality granular gray cast iron or alloy cast iron, with hardness conforming to the national standard, which should be between HB170-220. The working surface should be processed by scraping; for "Grade 3" flat plates, planing can also be used. The surface roughness of the planed working surface, measured by the average deviation of the contour Ra value, should not exceed 5 μm. The working surface of the cast iron platform must be flat and smooth, free from scratches, bumps, rust, and other surface defects that could affect its use.
The flatness of the test equipment base iron base plate working surface refers to the distance between the two parallel planes that enclose the actual working surface with the smallest possible separation. This value can be determined through "datum transformation" based on the verification results of the diagonal method or the ring method. The flatness of the plate working surface is a key precision indicator for measuring plate quality. The accuracy level of the plate is determined based on the allowable tolerance values of the flatness of the working surface, so it is essential to prioritize the verification of the flatness of the plate working surface. The accuracy of the flatness verification ensures the quality of the plate's use.
The test equipment base iron base plate is often used as a reference surface, so the accuracy requirements for the working surface of the cast iron plate are very high. Additionally, the working surface dimensions are generally large, which determines the precision of the plate verification and the complexity of the verification technology. The flatness of cast iron platforms can be classified into three grades: laboratory grade, calibration grade, and toolroom grade. The appropriate grade should be selected based on actual needs.
Grade A*: Its flatness (μm) = 1 + 1.6D2 (where D is the diagonal length or diameter of the platform), used for highly precise measurements, often in laboratories; * Grade: Its flatness has twice the error of Grade A*, commonly used in tool inspection rooms for precision measuring tool inspections; Grade B: Its flatness has four times the error of Grade A*, often used in tool inspection rooms or on-site for inspecting measuring tools or marking. The test equipment base iron base plate measuring tools produced by our factory undergo strict testing and fully meet standards, ensuring reliable use.