To measure the thickness of a piece, we use special tools for this type of inspections called precisely “ultrasonic thickness gauges”.
It is usually a control that is performed using only a technician who can easily store hundreds of measurements in the instrument.
The measurements are performed with the “pulse-echo” method, which is based on the measurement of the time taken by the ultrasound pulse to travel the thickness to be measured.
We have different types of instruments (portable):
- Thickness gauges that provide a numerical presentation of the signal, ie the instrument has a display on which only the numerical value of the measured thickness appears (Eg GE PoketMike). We usually use these tools on pieces of simple geometry on good quality materials.
- Thickness gauges that provide both a numerical presentation and an A-scan representation, used when there is a risk of false measurements due to the geometry of the piece or the type of material (Eg GE DMS2 or Olympus 45MG).
- Thickness gauges that are incorporated into ultrasonic devices used for discontinuities detection that provide both numerical and A-scan representation. (Eg GE DMS-Go)
We have various types of probes, single and double, with various frequencies and sizes for various applications, including:
- thickness measurements on high temperature pieces up to 538 °C
- thickness measurements on painted surfaces or with coatings up to 25 mm, without having to remove the protective layer
These instruments and probes are also used to establish the ultrasound velocity of a given material. In this case it is necessary to make a suitable stepped block of the same material under examination.
