S. S. K.Titus, S. K. Jain
DEVELOPMENT AND METROLOGICAL CHARACTERIZATION OF A 1000 N·m TORQUE COMPARATOR MACHINE FOR CALIBRATING TORQUE WRENCH TESTERS

The National Physical Laboratory, India NPL(I) has established torque scale up to 2000 N·m with calibration and measurement capability up to 0.01%, which has demonstrated a degree of equivalence in the BIPM CCM-T.K.1.1 key comparison. A torque comparator machine has been designed and developed at NPL, India for providing the national traceability of torque scale to the users without much degradation in the accuracy of measurement for certain industrial applications. This paper describes the salient features of the machine and the performance evaluation of the machine up to 1000 N·m. The expanded uncertainty associated with torque generated by this machine is found to be within ± 0.1% which is adequate for performing the calibration of industrial type torque wrench testers.

Toshiyuki Hayashi, Yoshihisa Katase, Hiroshi Maejima,Yukio Yamaguchi, Kazunaga Ueda
RENOVATION OF NMIJ'S 54 kN DEAD-WEIGHT FORCE STANDARD MACHINE INTO 100 kN MACHINE

NMIJ's 54 kN dead-weight force standard machine (DWM) has been upgraded to a 100 kN DWM by replacing the old weights with newly designed ones. There are four major improvements: extending the capacity from 54 kN to 100 kN, realizing calibration forces in Newtons, enabling 8- or 10-step calibrations for 50 kN and 100 kN ranges, and reducing maintenance work by motorizing the weight lifting mechanism. The calibration capability of the renovated DWM was confirmed to be better than 2.0 × 10⁻⁵ in terms of relative expanded uncertainty when calibrating some of the best force transducers available on the market.

D. Quagliotti, A. Germak, A. Piccato, P. G. Spazzini
FEM SIMULATION ON AERODYNAMIC CHARACTERISTICS OF INRIM FORCE LABORATORY

In this paper a methodology for estimating the airflow effects in deadweight force standard machines, using simulations with finite elements method, is proposed.
Simulating the environment of the INRIM force laboratory, influenced by the air-conditioning system, has allowed to determine probable aerodynamic characteristics of the ambience housing the masses systems under study. Furthermore, the simulations revealed the probable airflow effects on a INRIM forthcoming deadweight force standard machine.

D. Crescini, P. Crescini
LOW COST THICK-FILM SENSOR WITH HIGH SENSITIVITY AND LOW CREEP FOR DYNAMIC FORCE MEASUREMENTS

The application of load cells in industry generally requires good basic materials and accurate performance in a wide range of environments. Difference exist in manufacturing technologies, intended application, performance and cost; however, frequency response and creep can be a common source of errors in standard strain gauge cells. In this paper we present a small structure based on piezoresistive effect, implemented in Thick-Film Technology (TFT) on 96% alumina substrate, working as load cell with high resonance frequency and low creep effects. The analytic model has been verified by using simulation of the finite element method (FEM), resulting in satisfactory agreement. Based on a figure of merit (the product of the sensitivity and the square of the resonant frequency), optimised design rules are obtained for the sensors of various measure-ranges from 1 N to 10 N.

M. H. Hu, J. Wang, Y. Zhang, C. Q. Cai, R. L. Zhong, H. Yao, J. A. Ding
RESEARCH ON MICRO-GRAM WEIGHT STANDARDS BELOW 1 mg IN NIM

Micro-gram weights have potential applications for the calibration of small force measurements and the sensitivity of mass comparators with high accuracy. However, the traceability of micro weights below 1 mg to the unit of SI is not identified in the OIML recommendation R111. In this paper, Micro weights made of aluminum ranging from 500 µg to 100 µg are tested with mass comparator (UMT5). The uncertainty of measurement results indicate that for 500 µg weight, the extended measurement uncertainty can be down to 3 µg. The calibration results indicate that the biggest uncertainty contribution is still from the standard weight.