How do conventional coating thickness gauges work?
The material surface protection, decoration of the formation of the cover layer, such as coatings, plating, dressing layer, paste layer, chemical generation of film, etc., in the relevant countries and international standards called cladding (coating).
Cladding thickness measurement has become an important part of the processing industry, surface engineering quality testing, 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-related projects, the cladding thickness has a clear requirement.
Cladding thickness measurement methods include: wedge cut method, light cut method, electrolysis method, thickness difference measurement method, weighing method, X-ray fluorescence method, β-ray backscattering method, capacitance method, magnetic measurement method and eddy current measurement method. The first five of these methods are destructive testing, measurement means cumbersome, slow, and more applicable to sampling inspection.
X-ray and β-ray methods are non-contact non-destructive measurements, but the device is complex and expensive, and the measurement range is small. Because of the radioactive source, the user must comply with the radiation protection norms. x-ray method can measure very thin plating, double plating, alloy plating. β-ray method is suitable for plating and substrate atomic number greater than 3 plating measurement. The capacitance method is only used for thickness measurement of insulating claddings of thin conductors.
With the increasing progress of technology, especially in recent years after the introduction of microcomputer technology, the use of magnetic and eddy current method of thickness gauge to miniature, intelligent, multi-functional, high-precision, practical direction into a step. Measurement resolution has reached 0.1 micron, accuracy can reach 1%, 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.
The non-destructive method neither destroys the cladding nor the substrate, and the detection speed is fast, which can make a large number of inspection work economically.
