About the classification and measurement principles of coating thickness gauges
Regarding the classification and measurement principles of coating thickness gauges, with the increasing advancement of technology, especially after the introduction of microcomputer technology in recent years, thickness gauges using magnetic methods and eddy current methods have become miniature, intelligent, multi-functional, high-precision, and practical. a step further in the direction. The measurement resolution has reached 0.1 micron, and the accuracy can reach 1%, which has been greatly improved. It has a wide range of applications, wide measuring range, easy operation and low price. It is the most widely used thickness measuring instrument in industry and scientific research. The non-destructive method neither damages the coating nor the base material, and the detection speed is fast, allowing a large number of inspections to be carried out economically.
Coating thickness measurement has become an important part of quality inspection in the processing industry and surface engineering, and is an essential means for products to meet excellent quality standards. In order to internationalize products, my country's export commodities and foreign-related projects have clear requirements for the thickness of the coating.
The main measurement methods for coating thickness include: wedge cutting method, light interception 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 Law etc. The first five of these methods are destructive testing. The measurement methods are cumbersome and slow, and they are mostly suitable for sampling inspection.
X-ray and β-ray methods are non-contact and non-destructive measurements, but the devices are complex and expensive and the measurement range is small. Due to the presence of radioactive sources, users must comply with radiation protection regulations. The X-ray method can measure extremely thin coatings, double coatings, and alloy coatings. The β-ray method is suitable for measurement of coatings and coatings whose atomic number is greater than 3. The capacitance method is only used when measuring the thickness of insulating coatings on thin conductors.
Coating thickness gauge measurement principles and instruments About the classification and measurement principles of coating thickness gauges
Magnetic force measurement principle and thickness gauge
The attraction force between the magnet (probe) and the magnetically permeable steel is proportional to the distance between the two. This distance is the thickness of the coating. This principle is used to make a thickness gauge, which can be measured as long as the difference in magnetic permeability between the coating and the base material is large enough. Since most industrial products are stamped from structural steel and hot-rolled and cold-rolled steel plates, magnetic thickness gauges are the most widely used. The basic structure of the thickness gauge consists of magnetic steel, relay spring, scale and self-stop mechanism. After the magnetic steel is attracted to the object to be measured, the measuring spring is gradually stretched and the pulling force is gradually increased. When the pulling force is just greater than the suction force, the thickness of the coating can be obtained by recording the pulling force at the moment the magnet is detached. Newer products can automate this recording process. Different models have different measuring ranges and applicable occasions.
This instrument is characterized by easy operation, durability, no power supply, no calibration required before measurement, and low price, making it very suitable for on-site quality control in workshops.
