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As the national metrology institute (NMI), we are focusing on the development and dissemination of measurement standards, promotion of measurement standards utilization, development of measurement technologies related to measurement standards, legal metrology work and training of experts. Our activity covers engineering, physical, material, and chemical measurement standards. It also covers development of measurement and analytical instrumentation. We also coordinate international activities on metrology standards as a national representative.
Researchers at AIST have developed a technique to improve the reliability of shape measurement on industrial products. Several industrial products need to be manufactured with micrometer-order precision. For turbine blades used in generators and engines, the slightest deviation from the designed shape not only affects the efficiency of power generation and rotation, but can also cause trouble during operation. Therefore, the shape of industrial products must be accurately evaluated using a Coordinate Measuring Machine (CMM). However, when curved surfaces with a radius of curvature smaller than a few millimeters are measured with a tactile CMM, errors of a few micrometers can occur due to the data processing in the measurement by use of a probe tip with a finite size of approximately 1 mm in radius. In this research, we have developed a method to reduce measurement variation to the sub-micrometer order by applying morphological operation, which is used for noise reduction in image processing and surface roughness measurement, to the measurement using a tactile CMM. We have also applied the developed method to the measurement of a turbine blade edge profile, and have demonstrated that the measurement variation is reduced. This is expected to improve the reliability of shape measurement on industrial products and lead to assurance of quality and safety, such as dimensional accuracy. Details of this research were published online in Precision Engineering on September 11, 2024.
Conventional and developed method for shape measurement of turbine blades, etc., using tactile coordinate measuring machine
The National Institute of Advanced Industrial Science and Technology (AIST) and Nichia Corporation have developed a light source with light-emitting diodes (LEDs) that replaces existing luminous intensity standard lamps by reproducing the standard spectrum of incandescent lamps as defined by the International Commission on Illumination (CIE). The comfortable lighting level in living and working spaces is evaluated by an illuminance meter. Illuminance meters (illuminance sensors) are familiar measuring instruments that are incorporated into smartphones and used for dimming displays, etc. It is mandatory for new automobiles sold after April 2020 to have automatic headlights in order to avoid no lights at dusk hours for a safety reason. The system is equipped with a function that automatically turns on the headlights when the ambient light level is less than 1 000 lx. In order to properly use illuminance meters from the viewpoint of safety management, it is important to measure and control illuminance accurately, for example, by having them calibrated traceable to the national measurement standards. Manufacturers and testing laboratories calibrate illuminance meters using "luminous intensity standard lamps," which are incandescent lamps calibrated to be traceable to national measurement standards. However, incandescent lamps are no longer produced worldwide, and as a result of this phase-out, the discontinued luminous intensity standard lamps have become a global concern. In response, AIST and Nichia Corporation have developed a light source (Illuminant A standard LED) that provides the standard spectrum (CIE standard illuminant A) using LEDs. The Illuminant A standard LED not only meets the specifications for spectrum and illuminance values required for calibration of illuminance meters, but also improves the aging rate to about 1/20 of a luminous intensity standard lamp by an appropriate seasoning process of the LED package. As a result, it is expected to extend the recalibration periods and improve the measurement uncertainty in manufacturers and testing laboratories. Details of this technology were published in Measurement on August 16, 2024.
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