Film thickness tester is a common equipment coating detection tool, the use of magnetic thickness measurement method, can easily measure the thickness of non-magnetic coating on ferromagnetic materials, so the film thickness tester is sought after by many manufacturers. It has high requirements for accuracy in ordinary use, but there will still be errors, so what factors will affect the performance of the film thickness tester? The following is shared by Shenzhen Liyi Company:

1. Magnetization of matrix metal

Because the magnetic measurement method of the film thickness tester is affected by the magnetic change of the base metal (in practical applications, the change in the magnetic properties of mild steel can be considered slight). In order to avoid the influence of heat treatment, cold working and other factors, the instrument should be calibrated on an iron substrate with the same properties as the plated metal. And each film thickness tester has a critical thickness of the matrix metal, greater than this thickness measurement is not affected by the matrix thickness.

2. Edge effect

Because the film thickness tester is sensitive to steep changes in the surface shape of the test piece, it is not reliable to measure near the edge or inner corner of the test piece. Therefore, the curvature of the film thickness tester has an effect on the measurement, and this effect increases significantly with the decrease of the curvature radius. Therefore, measurements should not be made on the bending surface of the specimen beyond the allowable radius of curvature.

Third, surface roughness

Substrate metal and surface roughness have influence on the measurement of film thickness tester. Rough surfaces can cause systematic and accidental errors. Each time you measure, increase the number of measurements at different positions to overcome this accidental error. If the base metal is rough, it is necessary to take several positions on the uncoated rough similar base metal specimen to check the zero of the instrument; Or remove the coating layer on the base metal with a non-corrosive solution, and then check the instrument zero.

4. Magnetic Field

The strong magnetic field generated by various electrical equipment around will interfere with the thickness measurement work of the film thickness tester. And the film thickness tester is sensitive to attachments that prevent the probe from coming into close contact with the surface of the coating. Therefore, the attached material must be removed to ensure that the probe is in direct contact with the surface of the covering layer. It is worth noting that the probe is kept perpendicular to the specimen surface during measurement.

The above factors will affect the performance of the film thickness tester, and users need to pay special attention. In fact, any kind of equipment will have an impact error, especially for more sophisticated instruments, all improper operations may have a great impact on it, improving professional literacy is the key to avoid improper operation.