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Abstract. This paper reports work carried out to determine the influence of the Pyramidal indenter geometrical errors and tolerances on the accuracy of Vickers hardness measurements. The angle between the opposite faces and line of conjunction of nine indenters were measured by the optical comparator. The influence of the indenter geometry on the hardness accuracy is investigated. Three calibrated reference hardness test blocks were used to check the Vickers hardness test using the nine selected indenters. The results show that the geometrical error of the indenters (specially the angles) considerably affects the accuracy of the hardness measurement. Finite element analysis of the indentation process into metallic test pieces was conducted. Comparison of the experimental results with the numerical findings was discussed. Errors in the experimental values are correlated with measured tolerances in the angles between faces.

Misalignment of torque calibration machines can cause parasitic bending loads inside the torque transducers in use. These parasitic loads may affect the machine uncertainty, specially for secondary torque calibration machines. Therefore, this study discusses the contribution of misalignment to the measurement uncertainty for a newly designed 3 kNm secondary vertical torque calibration machine. Radial axes shift up to 4 mm was applied which introduce small increased uncertainty.

This paper details the results of a bilateral comparison carried out between the national force standard machines of Egypt and the United Kingdom. The results indicate that the uncertainty claims of the two laboratories can, in general, be supported. Recommendations on revised protocols to be used for future comparisons are given.

This paper presents a developed design and construction to improve the performance and increasing the density measuring capability of the previous Hydrostatic Weighing Apparatus (HWA-NIS) at the National Institute of Standards (NIS) up to 20 kg. The previous (HWA-NIS) has been constructed up to 10 kg on 2014. The 2-Positions mass handler in the previous (HWA) was developed with 4-Positions pentagon shape to be able to make handling for individual masses in a group at once, when transferring the traceability from the primary standard “the Silicon Sphere” to the standard masses in the density scale weighing process. The weighing pan in the previous (HWA) was developed with four suspension wires with a diameter of 0.3 mm each, leads to reduce the surface tension affect on the measurement uncertainty by factor four times. The density of the standard masses in the range from 2 kg up to 20 kg were measured with an improved expanded uncertainty from 0.150 kg/m3 to 0.078 kg/m3 respectively due to reducing the effect of surface tension via the developed design of the weighing pan.

The main goal of NIS is to provide traceability to international measurement standards to help the Egyptian industry to penetrate world markets. One of the most important fields of metrology is hardness measurements. A Primary Vickers Hardness Standard Machine (PVHM) was designed to improve the capabilities to qualify the primary hardness test blocks locally. The machine has been constructed to perform Vickers hardness test for scales HV10, HV20, HV30, and HV50 with expanded uncertainty of ±1.4 % .This standard machine has been metrologically characterized by NIS. In this paper metrological characterization of the machine will be shown. The characterization includes the methods and results of direct verification of influences parameters (test forces, indentation measuring system, indenter and test cycle time), and a comparison with PTB standard machine.