Precautions before using the coating thickness gauge
1. Carefully read the instruction manual of the instrument before use
Different manufacturers and different brands of instruments have different structures, keys, and calibrations. Therefore, you must read the instruction manual of the instrument carefully before using it to avoid errors in measurement data caused by misoperation.
2. Pay attention to the metal substrate material
The magnetism and conductivity of different metal matrix materials are different, which will affect the measurement results. The thickness measurement by the magnetic method is affected by the magnetic change of the base metal (in practical applications, the magnetic change of low carbon steel can be considered slight), in order to avoid the influence of heat treatment and cold working factors, it should be used with the same properties as the base metal of the test piece Calibrate the instrument with the standard sheet, or use the sample to be coated for calibration. Due to the different composition and heat treatment method of the base metal, the electrical conductivity is different. Therefore, the standard sheet with the same properties as the base metal of the test piece should be used to calibrate the instrument.
3. Pay attention to the shape of the test piece
In actual production, there are differences in the material thickness, shape, surface roughness, etc. of the workpiece, and these differences will affect the actual measurement results. Each instrument has a critical thickness of the base metal. If the thickness is greater than this, the measurement will not be affected by the thickness of the base metal. If the thickness of the specimen material is less than the critical thickness required by the instrument, the test result will be different from the actual thickness. Some instruments are very sensitive to the sudden change of the surface shape of the specimen, so the value measured near the edge or inner corner of the specimen will be unreliable, and the actual measurement should be selected away from the edge and inner corner. The surface of the specimen not only has a sharp change in shape, but also may have different curvatures. The measurement results of some instruments always increase significantly with the decrease of the radius of curvature. Therefore, even if the minimum radius of curvature is considered when selecting the instrument, the measurement should still be performed on a plane as much as possible.
