We report the implementation of a swept-sine dynamic force calibration system at NIST. This system is designed to perform primary calibration of force transducers at frequencies up to 2 kHz and forces up to 2 kN. We demonstrate the use of this system to measure the dynamic sensitivity of a strain-gauge based force transducer up to 2 kHz. The current dominant source of uncertainty in the system is angular motion of the calibration assembly.

The volume of a weight needs to be precisely measured for air buoyancy correction of the weight mass. To improve the measuring accuracy of volume determination with non-contact acoustic method, an acoustic measuring system with two measuring chambers is newly designed to compensate the non-linearly measuring errors. The volumes of mass standards ranging from 200 g to 5 kg are tested to evaluate the non-linearity errors of measurement, and a new test sequence is proposed theoretically to overcome the non-linearity of measurement and improve the measuring accuracy.

A study on transmission ratio distortion of 1 MN lever-type force standard machine has been performed using finite element method (FEM). The study involves the determination of deformation that occurs in the arms due to loading calculated using a software-based finite element method. The dimensions of the arms are taken from the manufacturing data. For verification purposes, the transmission ratio distortion resulted from the finite element modeling is compared to the linearity error calculated from results of a series of calibration using load cells as force transfer standards. The finite element simulation results show that the transmission ratio distortion is linear and amounted to approximately 270 ppm at maximum capacity. In addition, the study also concludes that the transmission ratio decreases with increasing forces. These results are in agreement with previous calibration performed by KRISS, Korea and acceptance test results from PTB Germany.

This paper presents the state-of-the-art calibration strategy for non-automatic weighing instruments (NAWI), based on the recently revised guideline EURAMET cg-18. Besides of the uncertainty at calibration, the document provides advice for the so-called uncertainty of a weighing result that describes the device performance during day-to-day use. The concept of minimum weight was added during a recent revision. The minimum weight is the smallest sample quantity that can be weighed on the device, still adhering to a predefined relative weighing tolerance requirement.

The paper describes two kinds of reference torque wrench, which were developed by our institute, and introduce the calibration methods by different torque standard machine. The experiment between two kinds of reference torque wrench has been done. The result was discussed in the paper.