Regulations to be followed when using a coating thickness gauge
Characteristics of matrix metal
For magnetic methods, the magnetic properties and surface roughness of the base metal of the standard sheet should be similar to those of the base metal of the specimen.
For the eddy current method, the electrical properties of the standard substrate metal should be similar to those of the specimen substrate metal.
B Base metal thickness
Check if the thickness of the base metal exceeds the critical thickness. If not, use one of the methods in 3.3 for calibration.
C Edge effect
Measurements should not be taken at sudden changes in the vicinity of the specimen, such as edges, holes, and internal corners.
DCurvature
Measurements should not be taken on the curved surface of the specimen.
Number of readings for e
Usually, due to the fact that each reading of the instrument is not exactly the same, it is necessary to take several readings within each measurement area. The local differences in the thickness of the covering layer also require multiple measurements to be taken within any given area, especially during rough surface construction.
F Surface cleanliness
Before measurement, any attached substances such as dust, grease, and corrosion products should be removed from the surface, but do not remove any covering materials
The magnetic method for thickness measurement is affected by the magnetic changes in the base metal (in practical applications, the magnetic changes in low-carbon steel can be considered minor). In order to avoid the influence of heat treatment and cold working factors, the instrument should be calibrated using a standard piece with the same properties as the base metal of the specimen; Calibration can also be performed using specimens to be coated.
