Why the ultrasonic thickness gauge measurement results will be biased
Ultrasonic thickness gauge national standard error requirements
Now there has been a resolution of 0.001mm ultrasonic thickness gauge, such as Zhongke Park Road's high-precision ultrasonic thickness gauge PD-T7, the error has been stabilised at 0.01mm, i.e., within 10 microns.
Measurement limit, ordinary thickness gauge using double crystal probe, measurement of the lower limit is generally in the plane carbon steel 0.8mm, curved carbon steel 1.2mm, the lower limit of the curved surface will be greater than the plane, exceeding the limit will result in the value of much larger, it is not an error at this time, but can not be measured. Single crystal probe PD-T7 ultrasonic thickness gauge measuring plane carbon steel lower limit to 0.15mm.
Material surface roughness, flatness impact, this is easy to understand, ultrasonic thickness gauge measurement is the average value below the probe.
Surface coating impact is also great, can not be ignored.
Material internal defects:
Castings, glass steel and other internal defects more materials, may not be measured low, only the location of the measured defects, this time to choose a high penetration probe and with gain adjustment instrument, such as PD-T8 ultrasonic thickness gauge, you can adjust the gain to achieve better measurement results.
The influence of temperature (material temperature and ambient temperature)
1, the influence of material temperature, the higher the temperature of the object to be measured, the speed of sound at the end of the month, the speed of sound measurement results obtained with room temperature will be higher than the actual bias.
2: hand on the probe temperature effect, will produce temperature drift, over a period of time the actual have to do calibration, you can choose PD-T7 ultrasonic thickness gauge, use without calibration, but also to maintain high accuracy measurement.
The most important point, the speed of sound
Ultrasonic thickness gauge to accurately calculate the speed of sound, do not recommend the use of self reference speed of sound, the same material, different grades, the speed of sound varies greatly, such as stainless steel speed from 5200-5900, the speed of sound is not the right will produce a great error.
