What is coating tester?
can non-destructively measure the thickness of non-magnetic coatings (such as aluminum, chromium, copper, enamel, rubber, paint, etc.) on magnetic metal substrates (such as steel, iron, alloy, and hard magnetic steel, etc.) and the thickness of non-conductive cladding (such as enamel, rubber, paint, plastic, etc.) on non-magnetic metal substrates (such as copper, aluminum, zinc, tin, etc.).Paint thickness tester
has the characteristics of small measurement error, high reliability, good stability, ease of operation, and so on. The paint thickness tester is an essential test instrument for controlling and ensuring product quality. It is widely used in the manufacturing industry, metal processing industry, chemical industry, commercial inspection, and other testing fields.
Working principle of coating tester
Coating tester uses the electromagnetic induction method to measure the thickness of the coating. The probe located on the surface of the part produces a closed magnetic circuit, which will change to varying degrees as the distance between the probe and the ferromagnetic material changes, causing a change in the magnetic resistance and the inductance of the probe coil. Using this principle, the distance between the probe and the ferromagnetic material can be accurately measured, which means the thickness of the coating.
Feature of coating tester
a. Two measurement methods, continuous (CONTINUE) and single measurement (SINGLE).
b. Two working methods are available, the direct method (DIRECT) and the grouping method (APPL).
c. With five statistics: mean value (MEAN), maximum value (MAX), minimum value (MIN), number of tests (NO.), standard deviation (S. DEV)
d. It can be zero-point calibration and two-point calibration, and the basic calibration method can be used to correct the system error of the probe.
e. It can be zero-point calibration and two-point calibration, and the basic calibration method can be used to correct the system error of the probe.
f. It has a storage function: 300 measurements can be stored.
g. It can set the limit boundary. It can automatically alarm the measured value outside the limit.
h. It has the function of communication with a PC. It can transmit the measured value and statistical value to the PC for further processing of data by a coating tester.
i. It has the function of power under-voltage indication.
j. The operation process has a beeping sound prompt.
k. It has the error prompt function.
l. It has the function of automatic power off.
Technology principle of coating tester
Paint thickness tester
A. Magnetic suction force measurement principle
The magnitude of the suction between the permanent magnet (probe) and the magnetically conductive steel is proportional to the distance between the two, which is the thickness of the cladding. This principle is used to make a coating tester, as long as the difference between the permeability of the cladding and the base material is large enough to be measured. Given the majority of industrial products use structural steel and hot-rolled and cold-rolled steel stamping, the magnetic thickness gauge is the most widely used. The basic structure of the thickness gauge consists of a magnet, a contact spring, a scale, and a self-stop mechanism. After the magnet steel and the measured object are absorbed, the measuring spring is gradually stretched afterward, and the pull force gradually increases. When the pulling force is just greater than the suction force, the magnets detach for a moment to record the size of the pulling force to obtain the thickness of the cladding. The newer products can automatically complete this recording process. Different models are available for different ranges and applications.
The characteristics of this instrument are easy to operate, durable, with no power supply, no calibration before measurement, and low price, which is very suitable for the workshop to do on-site quality control.
B. Magnetic induction measurement principle
When the magnetic induction principle is used, the cladding thickness is determined by using the magnitude of the magnetic flux from the probe through the non-ferromagnetic cladding and into the ferromagnetic substrate. The corresponding magnetic resistance can also be measured to indicate the thickness of the cladding. The thicker the cladding, the greater the magnetic resistance and the smaller the magnetic flux. Thickness gauges using the principle of magnetic induction can, in principle, have the thickness of the non-permeable cladding on a magnetically conductive substrate. The general requirement is that the substrate material permeability is above 500. If the cladding material is also magnetic, the difference in permeability with the base material is required to be large enough (e.g. nickel plating on steel). When the probe with the coil wound on the soft core is placed on the sample under test, the instrument automatically outputs the test current or test signal. Early products used a pointer-type meter head to measure the magnitude of the induced electric potential, and the instrument amplified this signal to indicate the thickness of the cladding. Recent circuit designs have introduced new technologies such as frequency stabilization, phase locking, and temperature compensation, using magnetoresistance to modulate the measurement signal. Patent-designed integrated circuits and the introduction of microcomputers have also been used, resulting in a substantial increase in measurement accuracy and reproducibility (almost an order of magnitude).
Magnetic principle thickness tester can be applied to accurately measure the steel surface paint layer, porcelain, porcelain enamel protective layer, plastic, rubber cladding, including nickel-chromium, including a variety of non-ferrous metal plating layer, as well as chemical and petroleum industry to be a variety of anti-corrosion coating.
C. Eddy current measurement principles
The high-frequency AC signal produces an electromagnetic field in the probe coil, in which eddy currents are formed when the probe is close to a conductor. The closer the probe is to the conductive substrate, the greater the eddy currents and the greater the reflected impedance.
This amount of feedback characterizes the size of the distance between the probe and the conductive substrate, which is the size of the non-conductive layer thickness on the conductive substrate. Since these probes specialize in measuring the thickness of cladding on non-ferromagnetic metal substrates, they are often called non-magnetic probes. The non-magnetic probe section uses high-frequency materials as coil cores, such as platinum-nickel alloys or other new materials. Compared with the magnetic induction principle, the main difference is that the probe is different, the frequency of the signal is different, and the size of the signal and the scale relationship is different.
The use of the eddy current principle of thickness gauge, in principle, all conductive body on the non-conductive body cladding can be measured, such as the surface of aerospace vehicles, vehicles, home appliances, aluminum doors and windows, and other aluminum products surface paint, plastic coating, and anodic oxide film. Cladding material has a certain conductivity, which can also be measured by calibration, but requires the ratio of the two-conductivity difference of at least 3-5 times (such as chromium plating on copper). Although the steel substrate is also a conductive body, this type of task is more appropriate for use of the magnetic principle of measurement.
D. Measurement principle of laser thickness tester
Using two laser sensors mounted below the measured object (paper), the sensors are fixed on stable support to ensure that the lasers of the two sensors can be aligned on the same point. As the measured object moves the sensor starts to sample its surface and measures the distance between the upper and lower surfaces of the target and the upper and lower pairs of laser displacement sensors, respectively, and the measured value is transmitted to the computer through the serial port and then processed by our thickness measurement software on the computer to obtain the thickness value of the target.
Thickness measurement method with coating tester
Coating thickness tester
A. Magnetic thickness measurement method
Applicable to the thickness measurement of non-permeable layers on magnetically conductive materials. Magnetically conductive materials are generally included steel, iron, silver, and nickel. This method has high measurement accuracy.
B. Eddy current thickness measurement method
Applicable to non-conductive layer thickness measurement on conductive metals, this method is less accurate than the magnetic thickness measurement method.
C. Ultrasonic thickness measurement method
It is suitable for the measurement of the thickness of multi-layer coating layers or for applications where neither of the above methods can be used. However, the product is generally expensive and the measurement accuracy is not high.
D. Electrolytic thickness measurement method
This method is different from the above three. It does not belong to nondestructive testing and needs to destroy the coating layer. Its general accuracy is not high, and the measurement is more troublesome than the other several.
How to buy coating tester?
ANTITECK provide lab equipment, lab consumable, manufacturing equipment in life sciences sector.
If you are interested in our coating tester or have any questions, please write an e-mail to firstname.lastname@example.org, we will reply to you as soon as possible.