Magnetic method for thickness of dry film

The magnetic method is a non-destructive instrumental measurement method. According to the different substrates to be tested, it can be divided into magnetic Thickness Gauges and non-magnetic Thickness Gauges, which are respectively suitable for the determination of the dry film thickness of paint films The main method of measurement. The magnetic Thickness Gauge mainly uses the principle of electromagnetic field reluctance to measure the thickness of the paint film through the magnitude , that is, the change of the magnetic flux caused by the change of the gap between the broken body and the magnetic substrate. There is also the principle of magnetic attraction method, that is, to measure the thickness of the paint film by the force required to overcome the magnetic attraction between the permanent magnet and the magnetic substrate. The non-magnetic Thickness Gauge uses the principle of eddy current thickness measurement to measure, that is , the size of the induced eddy current changes with the thickness of the instrument probe coil and the paint film thickness of the metal substrate. The thickness of the coating on the magnetic backplane.

Magnetic method to measure dry film thickness with figure 1

Instruments and Materials

Thickness gauge: the accuracy is 2µm, there are desktop and portable, and the specifications include dial type and digital display type. Figure 1-29 is a dial type Mikrotest magnetic Thickness Gauge using the principle of magnetic attraction method; Figure 1-30 It is an El cometer345 Thickness Gauge using the principle of magnetic flux . Figure 1-31 is a Thickness Gauge using the eddy current principle.

test methods

(1) Dial Thickness Gauge

① Manually place the measuring head on the paint film to be tested, slowly push the instrument dial forward with your fingers, stop pushing when you hear a " click" , and the reading pointed by the pointer is the paint film thickness of the sample.

②Automatically push the dial forward to the maximum range, press the button, and the instrument will automatically measure.

(2) The digital display magnetic Thickness Gauge is carefully adjusted to the zero position on a reference surface similar in nature to the test substrate, and then calibrated with the standard sheet attached to the instrument. When measuring, place the probe on the sample plate, take measurements at the upper, middle and lower positions of not less than 1000 cm from the edge, and read the value of the paint film thickness.