Calibration Services
Our group provides measurement standards related to the hardness field and underwater ultrasonic waves.
For inquiries and applications for calibration services, please visit the Calibration and Contract Testing page of the National Metrology Institute.
Hardness standard
■Rockwell hardness standard
Rockwell hardness test is measurement method capable of direct numerical reading, and widely-used method in industrial field such as automobile. NMIJ provides Rockwell C scale hardness standard (for steel material), and Rockwell B scale hardness standard (for soft iron, brass).
| Calibration type | Rockwell C scale hardness |
| Calibration item | Rockwell hardness standard block (C scale) |
| Scope of calibration | 20 HRC-65 HRC |
| Calibration type | Rockwell B scale hardness |
| Calibration item | Rockwell hardness standard block (B scale) |
| Scope of calibration | 30 HRBW-100 HRBW |
| Note | Provided only with a tungsten carbide ball indenter |
Vickers hardness test is applied to samples of various material and thickness due to less dependence in test force. NMIJ provides Vickers hardness standard in the range of 200 HV-900 HV.
| Calibration type | Vickers hardness |
| Calibration item | Vickers hardness standard block |
| Scope of calibration | 200 HV-900 HV |
Brinell hardness test can obtain average hardess with respect to relatively large area. NMIJ provides Brinell hardness standard in the range of 200 HBW-500 HBW (for mainly soft steel).
| Calibration type | Brinell hardness |
| Calibration item | Brinell hardness standard block |
| Scope of calibration | 200 HBW-500 HBW |
| Note | Provided only with a tungsten carbide ball indenter Test force symbol: HBW2.5/187.5-HBW10/3000 |
Ultrasonic
Ultrasonic power is total energy of ultrasound emitted from an ultrasonic transducer per unit time and is one of the key quantities for evaluating ultrasonic field, as well as ultrasonic pressure. We have been providing the calibration service for ultrasonic power in the range of 0.1 mW to 100 W using the following two methods. In the range below 15 W, ultrasonic power is calibrated using radiation force balance method using an electronic balance. In the range above 15 W, it is calibrated using calorimetric method, which measures the ultrasonic power from the heat generation of water.
| Device under test | Circular ultrasonic transducer |
| Calibration range | 1 mW ≤ P ≤ 15 W (0.5 MHz ≤ f ≤ 15 MHz) 1 mW ≤ P ≤ 500 mW (15 MHz ≤ f ≤ 20 MHz) 15 W ≤ P ≤ 100 W (1 MHz ≤ f ≤ 3 MHz) |
| Calibration and measurement capability |
5 % - 12 % (1 mW ≤ P ≤ 15 W) 9 % (15 W ≤ P ≤ 100 W) |
| Calibration method | Radiation force balance method (based on IEC 61161) and calorimetric method |
■Ultrasonic pressure standard (Calibration of free-field sensitivity for a hydrophone)
A hydrophone is an underwater device that transforms ultrasonic pressure into voltage signal. A hydrophone sensitivity, a coefficient convert voltage signal into ultrasonic pressure, is required in order to measure ultrasonic pressure using a hydrophone precisely. We have been providing the calibration service for hydrophone sensitivity by substitution method using the reference hydrophone calibrated by reciprocity and interferometric methods.
| Device under test | Hydrophone |
| Calibration range | 0.1 MHz ≤ f ≤ 40 MHz |
| Calibration and measurement capability |
10 % - 13 % (0.1 MHz ≤ f ≤ 1 MHz) 6.1 % - 8.8 % (0.5 MHz ≤ f ≤ 20 MHz) 13 % (21 MHz ≤ f ≤ 30 MHz) 17 % (31 MHz ≤ f ≤ 40 MHz) |
| Calibration method | Substitution calibration using the reference hydrophone calibrated by reciprocity method (based on IEC 60565, range: 0.1 MHz-1 MHz) and interferometric method (based on IEC 62127-2, range: 0.5 MHz-40 MHz) |