Now the thickness gauge equipment has been widely used in many fields. I will introduce some related principles of the thickness gauge equipment.
The eddy current thickness gage is based on the eddy current thickness gage. In principle, the non-conductive coating on all electrical conductors can be measured, such as the surface of spacecraft, vehicles, household appliances, aluminum alloy doors and windows, and other aluminum products. , plastic coating and anodic oxide film. The coating material has a certain conductivity, and can also be measured by calibration. However, the conductivity ratio of the two materials is required to be at least 3-5 times different (such as chrome plating on copper). Although the steel matrix is ​​also conductive, such tasks are still measured using magnetic principles.
The high-frequency AC signal generates an electromagnetic field in the probe coil. When the probe is close to the conductor, eddy currents form in it. The closer the probe is to the conductive substrate, the larger the eddy current and the larger the reflection resistance. This amount of feedback represents the size of the gap between the probe and the conductive substrate, that is, the thickness of the non-conductive coating on the conductive substrate. Because these probes measure the thickness of the coating on non-ferromagnetic metal substrates, they are often called non-magnetic probes. Non-magnetic probes use high-frequency materials for coil cores, such as platinum-nickel alloys or other new material coating thickness gauges. Compared with the principle of magnetic induction, the main difference is that the probe is different, the frequency of the signal is different, and the size and scale of the signal are different. Like the magnetic induction thickness gauge, the eddy current thickness gauge also achieves a resolution of 0.1um, a tolerance of 1%, and a high level of 10mm.
When the principle of magnetic induction is based on the principle of magnetic induction, the thickness of the coating is measured by the size of magnetic flux flowing from the probe through the non-ferromagnetic coating into the ferromagnetic base. The size of the magnetic resistance corresponding to it can also be measured to indicate the coating thickness. The thicker the coating, the greater the magnetic resistance and the smaller the magnetic flux. The thickness gauge using the principle of magnetic induction can, in principle, have a non-magnetically conductive coating thickness on a magnetically permeable substrate. General requirements for substrate magnetic permeability above 500. If the cladding material is also magnetic, the difference in magnetic permeability from the substrate is required to be large enough (eg, nickel plating on steel). When the probe on the soft core is placed on the test sample around the coil, the instrument automatically outputs the test current or test signal. Early products use an analog meter to measure the magnitude of the induced electromotive force. The instrument amplifies the signal and then instructs the thickness of the coating. In recent years, the circuit design has introduced new technologies such as frequency stabilization, phase locking of ultrasonic thickness gauges, and temperature compensation, and uses magnetic resistance to modulate measurement signals. The use of patented integrated circuits has also been introduced to introduce microcomputers, which have led to significant improvements in measurement accuracy and reproducibility (almost one order of magnitude). Modern magnetic induction thickness gauge, resolution up to magnetic induction thickness gauge_Electric eddy current measuring principle_Magnetic force measuring principle and thickness gage_Electrical eddy current principle thickness gage to 0.1um, promised error of 1%, range up to 10mm. The magnetic principle thickness gauge can be used to accurately measure the paint layer on the steel surface, porcelain, enamel protective layer, plastic, rubber coating, a variety of non-ferrous metal plating layer including nickel and chromium, and a variety of anti-corrosion coating Floor
Thickness meter related principles are the above points, I hope everyone will pay more attention when applied.