How a paint film thickness gauge works

The paint film thickness gauge is equipped with probes of different frequencies and wafer sizes, which can measure the surface coating thickness of different materials, and automatically adjust the error through functions such as probe-to-zero calibration and two-point calibration. , to improve the measurement accuracy. Different measurement methods are used depending on the material being measured. Among them, the two most commonly used measurement methods are magnetic induction measurement and eddy current measurement. The magnetic induction thickness measurement method is mainly used to measure the thickness of the non-magnetic conductive coating on the magnetic conductive material. When the probe of the paint film thickness gauge is in contact with the coating, the probe will form a closed magnetic circuit with the magnetic metal substrate, but the non-magnetic coating on the surface of the magnetic metal will block the magnetic circuit, resulting in a change in magnetoresistance. The amount of change in magnetoresistance, the thickness of the surface covering layer can be obtained. Eddy current thickness measurement is used to measure the thickness of non-conductive coatings on conductive materials. This measurement method is less accurate than the magnetic thickness measurement method. The eddy current thickness measurement method can achieve non-destructive measurement, and measure the thickness of non-magnetic metal substrates such as aluminum, copper, and stainless steel on non-conductive cladding, which includes paint, plastic, rubber, powder, etc. The ultrasonic thickness measurement method currently has a limited application range, and only individual foreign manufacturers use this type of paint film thickness gauge. The ultrasonic thickness measurement method is mainly used to measure the thickness of the coating or coating. Although its measurement accuracy is not high, it can be used in situations where the above two methods cannot be achieved. The electrolytic thickness measurement method is different from the above three measurement methods, because the electrolytic thickness measurement method needs to destroy the coating on the surface of metals and other materials, and the accuracy is not high, which may cause some problems and cannot achieve non-destructive testing. The paint film thickness gauge is more sensitive to the attachments that hinder the magnetic head and the surface of the cover layer. Therefore, everyone should remove the attachments on the surface before measuring to ensure that the measurement results are not affected by them. In short, the paint film thickness gauge can measure the thickness of the surface coating by collecting changes in metal magnetism or conductivity. Usually, the measured data is affected by factors such as the electrical conductivity of the body metal and the change in metal magnetism, and there are certain errors. , requires the use of coated specimens for calibration.