Coating thickness gauges classification and measuring principle
Coating thickness gauge according to the measurement principle generally have the following five types:
1. Magnetic thickness gauge method: detection of magnetic metal substrate (such as steel, alloy, magnetic steel, iron Fe, cobalt Go, nickel Ni) on the thickness of non-magnetic cover layer (such as aluminium, chromium, copper, zinc, tin, enamel, rubber, plastic, paint, etc.)
and the thickness of non-conductive covering layers (e.g. enamel, rubber, paint, plastic, etc.) on non-magnetic metal substrates (e.g. copper, aluminium, zinc, tin, etc.). This method of measurement is highly accurate.
2. Eddy current thickness measurement method: applicable to conductive metals on the non-conductive layer thickness measurement. This method is less accurate than the magnetic thickness measurement method.
3. ultrasonic thickness measurement method: at present there is no such method to measure the thickness of the coating layer, individual manufacturers abroad have such instruments, applicable to multi-layer coating layer thickness measurement or the above two methods can not be measured on the occasion. But the general price is very expensive, and the accuracy is not high.
4. Electrolytic thickness measurement method: This method is different from the above three, does not belong to the scope of non-destructive testing, need to destroy the coating layer, generally speaking, the accuracy is not high, the measurement is also more troublesome than other methods.
5. Radiometric thickness method: the price of this instrument is very expensive (generally more than 100,000RMB), for some special occasions. The most common domestic use is the first two methods.
The material surface protection, decoration of the formation of the cover layer, such as coatings, plating, dressing, paste layer, chemical film, etc., in the relevant countries and international standards known as cladding (coating).
Coating thickness measurement/coating thickness gauge has become an important part of the processing industry, surface engineering quality inspection, is a product to achieve superior quality standards of the necessary means. In order to make the product internationalisation, China's export commodities and foreign projects, the thickness of the coating layer has a clear requirement.
With the increasing progress of technology, especially after the introduction of microcomputer technology in recent years, the thickness gauge using magnetic method and eddy current method to miniature, intelligent, multi-functional, high-precision, practical direction. Measurement resolution has reached 0.1μm, accuracy can reach 0.01, a substantial improvement. It applies to a wide range, wide range, easy to operate and inexpensive, is the most widely used industrial and scientific research thickness gauge.
