Coating thickness gauges generally have the following types based on measurement principles:

Magnetic thickness measurement method, suitable for measuring the thickness of non-magnetic layers on magnetic materials.Magnetic materials are generally:steel\\iron\\silver\\nickel.This method has high measurement accuracy.

Eddy current thickness measurement method, suitable for measuring the thickness of non-conductive layers on conductive metals.This method has lower accuracy than magnetic thickness measurement.

Ultrasonic thickness measurement method is currently not used in China to measure the thickness of coating layers,Some foreign manufacturers have such instruments,Suitable for measuring the thickness of multi-layer coating or in situations where neither of the above methods can measure it.But generally, the price is expensive\\The measurement accuracy is also not high..

Electrolytic thickness measurement method, which is different from the above three methods,Not classified as non-destructive testing,Need to destroy the coating layer.Generally, the accuracy is not high.Measuring is more complicated than other methods.

Radiometric thickness measurement method, suitable for some special occasions..