Ultrasonic and eddy current paint thickness meters

Eddy current paint thickness meter
Eddy current thickness gauges are generally used to measure the thickness of insulating coatings on non-ferrous metal substrates. This method is also a non-destructive measurement method.
The instrument uses a fine wire coil capable of conducting high frequency AC (above 1MHz) to generate an alternating magnetic field on the surface of the instrument probe. When the probe approaches a conductive surface, the alternating magnetic field will form eddy currents on the surface. The characteristics of the base material and the distance between the probe and the base (that is, the coating thickness) will affect the size of the eddy current.
The eddy current generates a relative electromagnetic field, which can be sensed by the excitation coil or another adjacent coil.
The appearance and operation of the eddy current thickness gauge are similar to the electromagnetic induction thickness gauge. This type of instrument can measure almost all coating thicknesses on non-ferrous metals.
Like the electromagnetic induction thickness gauge, it usually uses a constant pressure probe and displays the measurement result on the LCD screen. In addition, they can also choose to store the measurement results or analyze the readings instantly and output them to a printer or computer for further inspection.
The measurement deviation is generally about ±1%. The test is sensitive to surface roughness, curvature, substrate thickness, the type of metal substrate material and the distance between it and the edge. The test method can refer to international standards such as ASTM B 244, ASTM D 7091 and ISO 2360.
Nowadays, many thickness gauges combine the principle of electromagnetic induction and eddy current into one system. Some simple measurement tasks can be automatically switched from one operating principle to another based on requirements to measure the coating thickness on most metals. These integrated systems have been widely recognized and welcomed by the paint industry and powder coating industry.
Three, ultrasonic paint thickness meter
The ultrasonic echo pulse technology used in ultrasonic thickness gauges is generally used to measure the thickness of the coating on the surface of non-metallic substrate materials (such as plastics, wood, etc.). Moreover, this method is a non-destructive measurement method and will not affect the measurement. The sample caused damage.
The probe of the instrument contains an ultrasonic transducer that can send pulses through the coating. The pulse is then reflected from the matrix material back to the transducer and converted into a high-frequency electrical signal. Through digital analysis of the echo waveform, one can effectively determine the thickness of the coating. In some cases, the instrument can also measure the thickness of a single layer in a multilayer system.
The measurement standard deviation of this method is generally about ±3%, and the measurement method can refer to the ASTM D6132 international standard.
Four, micrometer thickness gauge
People sometimes use a micrometer to measure the thickness of the coating. They have the advantage of measuring any coating/substrate combination, but the disadvantage is that they need to touch the exposed substrate surface.
Contacting the upper surface of the coating and the lower surface of the substrate is sometimes very difficult, and they are usually not enough to measure the thickness of some thin coatings very accurately and sensitively. Therefore, it is necessary to perform two measurements using this method, one on the surface with the coating, and the other on the surface without the coating. The difference between these two degrees, that is, the measured height difference, is the thickness of the coating. On some rough surfaces, this method generally measures the thickness of the coating at the highest point.