Automobile Steel Plate

The thickness of automobile body steel plates of different brands and models is different. For the same model, the thickness of the steel plates is also different in different parts of the body structure. Thin steel plates can bring the benefit of lightweighting, but also bring the disadvantage of not being able to withstand some accidental collisions. If thicker steel plates and high-strength steel plates are used, fuel consumption will increase due to increased weight, and the cost of production will also increase. Most of the steel plates for automobile bodies are stamped and formed by cold-rolled steel plates. The thickness of body steel plates generally from 0.8 mm to 2.0 mm.

 

Car Paint

Car paint is also a type of coating. Spraying paint on a car not only forms a protective film on the surface, making the car body less susceptible to corrosion, but also prolongs the service life of the car, and also gives people an aesthetic enjoyment. The thickness of car paint is related to the car model, color, and specific parts. It is generally between 120 and 180 microns.

 

Measurement Difficulties

The thickness of automobile steel plates and the thickness of car paint are both important. For conventional measurement methods, we need two essential instruments. One is a paint film thickness measurement instrument, the unit is microns. The principle of magnetic reflection measurement of coating thickness is used, and the error is about 1 to 2 microns.

Another instrument is the ultrasonic thickness gauge, which is measured in millimeters. When measuring metal without paint on the surface, such as steel plates, the thickness error is only about 1%. However, when measuring steel plates with paint, the error is not small due to the different propagation speeds of ultrasonic waves in steel plates and paint. Therefore, an ultrasonic thickness gauge with a coating penetration function must be used to penetrate the paint layer and measure the thickness of the steel plate.

 

Solution

Using the PM5 Gen2 ultrasonic thickness gauge, the coating mode with dual measurement options can measure the net material thickness and coating thickness respectively. Displaying the thickness of the automobile steel plate and the thickness of the car paint layer at the same time.

Since the thickness of the steel plate and paint layer to be measured is relatively thin, we need to use a delay line probe with a higher frequency to improve the resolution and make the measurement more accurate. The following picture is our testing result.