The car paint meter used to measure the paint thickness on automobile shells has a total of three test principles. According to the principle, it can be divided into magnetic thickness measurement, eddy current thickness measurement and ultrasonic thickness measurement. The paint film is mainly selected according to the material of the car casing. Automobile body materials are generally composed of metals such as steel, cast iron, aluminum and non-metal materials such as plastic, resin and rubber. Testing the thickness of paint films on different surfaces and different types of cars requires the use of car paint meters of different principles.
Both steel and iron are magnetic metals, so when measuring some steel or iron car bodies, magnetic thickness measurement is used to measure the paint film thickness. At present, the probe of the magnetic car paint meter which is more commonly used is to measure the paint film thickness covering the surface by measuring the magnetic path passing through the paint layer and the automobile substrate.
Since the end of the 1980s, many auto manufacturers around the world have begun researching aluminum car bodies. All-aluminum bodies use both steel and aluminum materials to make cars have more dynamic driving capabilities. The paint film thickness of an all-aluminum body cannot be measured using the above magnetic method, but it can be measured by the eddy current method. The eddy current method car paint meter can generate high-frequency electromagnetic field, which will generate eddy current when measuring aluminum and then calculate the thickness of automotive paint film by measuring eddy current and phase.
In addition to various metal materials used in automobile bodies, some non-metal materials such as plastic bumpers are also used. Ultrasonic method can be used to measure the paint film thickness on the plastic bumper. The ultrasonic car paint meter can send a pulse to the paint film, the pulse is reflected from the plastic to the transducer, and then converted into a high-frequency electrical signal. The paint film thickness on the plastic bumper surface can be calculated.
Of course, there are currently some car paint meters that use both magnetic and eddy current measuring principles. When measuring different positions of the car body, the instrument can automatically switch the measurement mode to quickly and accurately measure the paint film thickness at each position.