Painting a car is a multi-step process that requires applying multiple coats and measuring their thickness. In this article, we review the process of measuring the thickness of car paint layers and present a faster method that requires only one check.
How do you measure the thickness of car paint?
A car's paint is usually applied in four to five coats, and sometimes more, depending on the paint color and manufacturer. Typically, these coats include electrocoating, primer, basecoat and clearcoat on a metallic substrate, and for some colors, an additional layer of paint (mica).
After each coat of paint, thickness measurements - often expressed in mils or microns - must be taken to confirm that the specifications are met. And for each car, there may be 100 or more inspection points depending on the make and model. Coat thickness is usually measured at the same locations to track trends over time.
However, since four, five, or even six coats of paint are applied to cars, this process is tedious and requires many manual operations. Often, automotive paint thickness measuring tools only measure the total thickness after each coat is applied. This means that after each coat is applied, the total thickness must be measured and then manually subtracted to get the thickness of the newly applied coat.
Fortunately, there is a faster solution. Some advanced ultrasonic thickness gauges can provide both individual layer thickness measurement and total thickness measurement of multiple layers. This makes it possible to measure the thickness of the paint at the end of the production line, after all the layers have been applied, instead of after each layer.
Simultaneous measurement of the individual thickness of six paint layers
Among the advanced tools for making thickness measurements is the 72DL PLUS™ ultrasonic thickness gauge. This high-frequency, high-speed device can measure up to six layers of automotive paint. In a single check, it can provide the thickness of each layer and the total thickness of the layers.
For thickness measurement of ultra-thin layers such as paint layers, a high-frequency probe that uses frequencies up to 125 MHz is recommended. The probe must be able to move smoothly over the inspected part without abrading the painted sample. The 72DL PLUS meter works with high frequency probes up to 125 MHz, such as the M2104.
Automotive paint thickness measurement can be further simplified by using a gauge that stores routine inspection setups. The 72DL PLUS gauge is one such example, and it displays routine applications directly on the startup screen, so that all you need to do is retrieve a configuration to begin an inspection. Its intuitive software and large, clear touch screen make it easy to save inspection setups, take measurements and track thickness changes.
Measurement and visualization of the thickness of several layers of paint
Here is an example of how this setup can save time. Suppose an operator working at a car manufacturer is measuring the paint on a car that has a clear coat, a pigment coat, a primer coat and a primer. The 72DL PLUS meter shows the thickness of each of the four paint layers and the total thickness on the inspection screen in real time. Thus, the operator is able to get all the information he needs in a single inspection.
The operator can then use five different views for data presentation - A-scan, B-scan, A/B-scan, Trend and Zoom - to better see the thickness of each layer. The images below show some of the views that can be used to visualize the thickness of paint layers using the 72DL PLUS meter.
Individual paint layers presented in different measurement views on the 72DL PLUS meter. From top to bottom: B-scan, A-B-scan, Trend and Zoom.
Another useful visualization feature for measuring automotive paint thickness is guided inspection using a custom part map. This mapping shows an image of the part being inspected, with the inspection points clearly marked.
Ability to digitize and automate tasks
Measurement and inspection tools that simplify and accelerate processes are critical to increasing productivity on the production floor. With the gradual adoption of electric, connected and autonomous cars, an efficient paint thickness measurement process can help automakers streamline production and meet ever-changing customer demands.