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Adriana Vâlcu
CALIBRATION OF NONAUTOMATIC WEIGHING INSTRUMENTS

This paper describes the metrological requirements and the measurements methods for calibrating nonautomatic weighing instruments. It also may be a useful guideline for operators working in calibration laboratories accredited in various fields. This paper is also intended to enable metrology laboratories to prove a given expanded uncertainty using suitable procedures. Two examples of calibration methods are given: one for electronic weighing instruments and another for the mechanical instruments. The described methods include information regarding the measurements standards used for calibration, environmental conditions, calibration procedures and estimation of the measurement uncertainty.

M. Borys, T. Fehling, T. Fröhlich, D. Heydenbluth, M. Mecke, R. Schwartz
DESIGN AND PERFORMANCE OF THE NEW SARTORIUS 1 KG VACUUM MASS COMPARATOR AT PTB

A new type of a 1 kg vacuum mass comparator was developed in a collaboration between the Sartorius AG, the Technical University Ilmenau and the BIPM. The first comparator of this new type was installed at PTB. In this paper the set-up of the system and the local conditions are described. First results of measurements in air and in vacuum are presented.

Georg Wegener, Werner Nold, Jürgen Andrae, Kai Molitor
MEASUREMENT UNCERTAINTY OF ROTATING TORQUE TRANSDUCERS WHEN USED IN PARTIAL LOAD RANGES

The present contribution examines how metrological specifications can be derived for a given type of torque transducer when specifications for use in the full nominal measuring range are known, but the specifications for use in a partial load range are required. metrological properties of a transducer in a partial load range can be estimated from data taken from specifications or calibrations in the nominal load range.

José A. Robles Carbonell, Jorge L. Robles Verdecia, Alfonso Lobo Robledo
TORQUE STANDARD MACHINES AT CEM

Centro Español de Metrología has established a torque laboratory according to the State of the Art as a result of a cooperation project with PTB. This paper introduces the torque standard machines developed and installed at CEM, describes their main technical and metrological characteristics and shows some results of the performance studies and comparisons carried out.

J. C. Torres Guzmán, D. Ramírez Ahedo, J. P. Cruz, L. C. Cabral, R. Soares de Oliveira, R. de Freitas Guilherme
SIM TORQUE COMPARISON BETWEEN CENAM (MEXICO) AND INMETRO (BRAZIL) UP TO 100 N·m

A torque comparison was carried out between the Centro Nacional de Metrología, CENAM (in Mexico) and the Instituto Nacional de Metrologia, Normalização e Qualidade Industrial, INMETRO (in Brazil), in order to estimate the level of agreement for the realization of the quantity and the uncertainty associated to its measurement. The comparison was carried out in a range starting at 20 N·m and up to 100 N·m. The results obtained, deviations graphs (including the uncertainty for each torque applied of each laboratory) and the normalized error equation application results are presented in this document. This constitutes the first torque comparison within the Sistema Interamericano de Metrologia (Interamerican Metrology System, SIM) and has the classification number SIM.7.27 BK.

Hans W. Werner, Daniel Schwind
25 kN·m TORQUE CALIBRATION MACHINE REACHES U_bmc = 0.008% USING NEW DESIGN FEATURES

Due to the need to calibrate high-precision torque transducers also for production purposes, a suitable torque reference standard had to be built up. Using new design features and qualifying the calibration machine by self-contained measurements and advanced measurement uncertainty calculations, resulted in a best measurement capability of Ubmc = 0.008%.

Li To, Shang Weilu, Cheng Yongpei, Yan Kangping, Liu Zhong
100 N·m NEGATIVE STEP DYNAMIC TORQUE STANDARD MACHINE

100 N·m negative step dynamic torque standard machine is used to calibrate the dynamic characteristics of torque transducer. Through measurement of negative step excitation time τ,it can get the inherent frequency ωn. The paper describes the working principle, key technology, test data and the uncertainty analysis of the machine. The specification of machine is as follows: measurement range 100 N·m, τ ≤ 5ms, uncertainty U = 2.64%, k=2.

Jaime I. Hernández-Navarro, Gabriel Ascanio, Leopoldo Ruiz-Huerta, Alberto Caballero-Ruiz
MEASUREMENT OF TORQUE IN MICROMOTORS

This paper describes a dynamometer developed for the measurement of torque of micromotors as a function of the rotational speed. The operating principle of the device is based on that of a typical viscometer. The shaft of the micromotor to be tested is coupled to a small cylinder, which is placed concentrically into a larger cylinder. The motor torque is transmitted from the inner cylinder to the outer one by means of a well-known viscosity fluid. A pneumatic cylinder supports the outer cylinder, so that the test is performed under free-friction conditions and the torque is determined by a lever arm in contact with a load cell.

Min-Seok Kim, Jae-Hyuk Choi, Yon-Kyu Park
ACCURATE DETERMINATION OF SPRING CONSTANT OF ATOMIC FORCE MICROSCOPE CANTILEVER AND COMPARISON WITH OTHER METHODS

We present an AFM cantilever calibration system: Nano Force Calibrator (NFC), which can provide accurate spring constant calibrations with traceability to SI. Two types of commercial beam-shaped AFM cantilevers (contact and tapping mode) are investigated using the NFC. Uncertainty analysis reveals that the uncertainty of present method is less than 1%. In addition, comparison between other famous calibration methods (dimensional, cantileveron- cantilever, and Sader method) and the NFC method is performed to assess the uncertainties of other three methods. From the comparison results, we estimate that the uncertainties of dimensional, cantilever-on-cantilever, and Sader method are around 10-15%, 10%, and 15-40%, respectively.

Oliver Mack
A NEW CALIBRATION METHOD WITH STATIC LOADS FOR PIEZOELECTRIC FORCE TRANSDUCERS

This paper presents a new method for calibrating piezoelectric force transducers with static forces. Load cycles with pilgrim-steps and a special evaluation of the measuring results permit the determination of transducer coefficients that are independent of the linear drift of the charge amplifier. Consequently, the coefficients are independent of the measurement time and the time of load change of the force standard machine in use. It is shown that the new calibration method contributes essentially reducing the uncertainty of piezoelectric force transducers that are used in quasistatic and dynamic precision force measurements.

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