Evaluation of the expanded relative uncertainty of NIS developed dead weight machine

Abstract

Force and Material Metrology Department (FMMD) is a department within the National Institute forStandards (NIS), founded as early as 1963. The most important event achieved within the last few years at FMMD was constructing, evaluating & commissioning of Dead Weight Machines (DWMs), the Primary Standards for force measurements with ranges of 0.05-5kN, 0.5-50kN, 10-500kN, 500-1000kN and 100-5000kN. All are computerized and delivered by GTM Company except the 5kN machine which is a manually controlled machine, established through research works carried out by FMMD [1]. The FMMD was transferred to a new building which lead to dismantling the 5kN machine and re-assembling it in its new site. In addition, the machine was developed as a part of modernizing NIS force laboratory [2].This development entailed checking the design of machine main frame using finite element method, determining the gravitational acceleration in the new building, determining the air density surrounding the machine, adjusting the machine weights to enhance the accuracy associated with the measurement results, beside designing a full computerized control circuits to control the selection and application of the loads of the machine and finally estimating the relative expanded uncertainty of the machine.