The challenges of choosing an optimally thick surface plate (SP) were noticed during the calibration of pressure measuring instruments against pressure balance type primary and secondary standards. This has motivated authors to investigate this issue in detail. It is observed that the traditional workstation made of steel sheets may not be flat enough to generate accurate pressure measurement results. These SPs are also regularly used in the metrology laboratories, inspection rooms, and manufacturing industries. Whenever precise and accurate measurements and inspections are performed, the irregularities of the working surfaces lead to incorrect results. Therefore, focused research is carried out by analyzing some of the standard granite plates. Usually, manufacturers design, fabricate, and install the SPs as per the recommendation of the respective documentary standards. The standards provide the requirements and specifications of the flatness tolerances for different sizes of the SPs. However, these standards do not precisely specify the optimum thickness of the SP. Standards also suggest using finite element analysis to avert complex mathematical procedures. The simulation method precisely represents the individual case of installation/design. Therefore, the bending cases due to self-weight and rigidity tests are simulated to determine the deformations of the various sizes of granite SPs. Their results led to devising the proposed optimization of the thickness of metrological surface plates. In the present investigation, granite SPs of different sizes are simulated. The critical thickness is observed when the deformation reduces to its optimum level. The surface deflection against the load is minimum at critical thickness values. The results obtained in the optimization are compared with the standard values.
|Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture
|Published - 27 Aug 2022