Coating Thickness Gauge (Paint Thickness Gauge) Measuring Principle10 years ago
Coating Thickness Gauge NDT520 adopts two methods of thickness measurement, magnetic or eddy current, which can non-destructively measure the thickness of non-magnetic coatings (such as aluminum, chromium, Copper, enamel, rubber, paint, etc.) and the thickness of non-conductive coatings (such as: enamel, rubber, paint, plastic, etc.) on non-magnetic metal substrates (such as copper, aluminum, zinc, tin, etc.).
Coating Thickness Gauge (Paint Film Thickness Gauge) Measuring Principle:
a) Magnetic method
When the measuring head is in contact with the covering layer, the measuring head and the magnetic metal substrate form a closed magnetic circuit. Due to the existence of the non-magnetic covering layer, the reluctance of the magnetic circuit changes, and the thickness of the covering layer can be derived by measuring the change.
b) Vortex method
A high-frequency alternating current is used to generate an electromagnetic field in the coil. When the probe is in contact with the covering layer, an eddy current is generated on the metal substrate, and a feedback effect is generated on the coil in the measuring head. The covering layer can be derived by measuring the magnitude of the feedback effect thickness of.
Classification of Coating Thickness Gauge
1. Eddy current thickness measurement method: suitable for measuring the thickness of non-conductive layers on conductive metals. This method is less accurate than magnetic thickness measurement method
2. Magnetic thickness measurement method: It is suitable for measuring the thickness of the non-magnetic layer on the magnetic material. The magnetic material is generally: steel\iron\silver\nickel. This method has high measurement accuracy
3. Ultrasonic thickness measurement method: At present, there is no such method in China to measure the thickness of the coating. Some foreign manufacturers have such instruments, which are suitable for the measurement of the thickness of multi-layer coatings or the occasions where the above two methods cannot be measured. But it is generally expensive and the measurement accuracy is not high.
4. Radiation thickness measurement method: This kind of instrument is very expensive (generally above 100,000 RMB), and is suitable for some special occasions. The most commonly used methods in China are the first and second methods.
5. Electrolytic thickness measurement method: This method is different from the above three methods. It does not belong to non-destructive testing and needs to destroy the coating. The general accuracy is not high. It is more troublesome to measure than other types
