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About coating thickness meters
Coating thickness meters have existed since the mid-1950er, but the first instruments were limited to determining the thickness of coatings and other corrosion protection coatings on steel. They were moderately accurate and not easy to use. In the meantime, coating thickness meters can measure virtually any coating on any surface. You can find out how they work in our guide.
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What was a layer thickness meter?
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What types and types of layer thickness measuring devices are available?
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Purchase criteria for coating thickness meters – what is it all about?
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Conclusion: How to buy the right layer thickness meter
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Our practical tip: Create ideal measuring conditions
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FAQ – Frequently Asked Questions about Film Thickness Meters
What was a layer thickness meter?
A layer thickness gauge measures the thickness of a coating on metallic surfaces without any damage. . Coating thickness meters are also often referred to as paint coating gauges or paint thickness gauges. However, depending on the design of the device, paints are by no means the only coatings that can be measured with a modern digital coating thickness gauge.
Depending on whether the layer thickness is to be measured on ferrous metals or non-ferrous metals, different measuring methods are used. Magnetic induction is used for magnetizable surfaces. Here either a permanent magnet or a small electromagnet generates a magnetic field whose strength is then measured with a Hall sensor or a secondary coil.
Eddy current is used for non-magnetizable but electrically conductive carrier materials (such as aluminum, copper, brass, zinc and several stainless steel grades). In this case, a magnetic alternating field generates eddy currents in the base material, the strength of which is then used to determine the slice thickness.
Another method uses ultrasonic waves for measurement, whereby most devices are more suitable for measuring relatively thick layers due to a relatively high measuring range of about 1 mm upwards. Such coating thicknesses can be found, for example, in fire protection coatings, in the maritime sector and in special corrosion protection.
Another device attunement is the so-called material thickness measuring instruments, which, however, are not usually able to differentiate a coating on a base material and display it metrologically, but measure the overall material thickness up to about 300 mm.
Coating thickness meters are used to determine if paint has been applied to the correct thickness or to check the thickness of other coatings such as zinc, enamel or PTFE. However, this does not only work for paint and other real coatings, but also for films, adhesive tapes and protective bandages . Especially when measuring the coating thickness of paint in the car area , it is relatively easy to determine a subsequent coating after an accident or corrosion damage, since a noticeably higher reading indicates a repainting. For this reason, coating thickness measuring instruments are now a standard tool for experts, experts and car dealers.
What types and types of layer thickness measuring devices are available?
Coating thickness meters are available in coatings on ferrous metals , as well as for non-ferrous metals . However, often both measuring ranges are combined in one device, and in the case of measuring instruments with a permanently integrated probe, these are also designed for both procedures.
Layer thickness measuring instruments with cable-connected, external probe often permit an exchange with other measuring heads , for example for the measurement of iron or non-ferrous metals, or to meet different layer thicknesses as well as possibly limited space or very small measuring surfaces.
Special (usually also relatively expensive) coating thickness meters are even able to measure the thickness of coatings on some non-metallic base materials. For this purpose, an extensive ultrasonic measurement method is used, with the help of which the different sound propagation speeds in the different materials are evaluated. The thickness of the coating and the thickness of the carrier material are then displayed.
Coating thickness meters are now only available in digital versions. Depending on the equipment, they have additional features such as automatic underground detection, display lighting, min./max. display, hold function, alarm functions for measured value over or under-shooting, measured value storage function, PC interface and software for evaluation and documentation on the computer.
Very simple models designed for quick control of possible repainting on motor vehicles often have only three different colored LEDs, each of which is assigned to a layer thickness range. They do not allow a layer thickness measurement by means of a measured value, but serve only as an indicator .
Purchase criteria for coating thickness meters – what is it all about?
Measurements should not be carried out exclusively on steel and iron bases, a device for ferrous and non-ferrous metals is the clearly universal variant . Especially in the automotive sector, a trend is emerging for the increased use of aluminum components that cannot be investigated with a pure Fe mode model.
Assessors and maintenance personnel benefit from devices with extensive equipment such as automatic selection of the measuring mode and the possibility of data storage including evaluation and documentation possibility.
Devices with replaceable cable probes can be used most flexibly, as they allow the device display to be read even at unfavorable places and allow the connection of different probe types.
Conclusion: How to buy the right layer thickness meter
If you work with different basic materials more often, then a layer thickness measuring device with automatic material recognition is the right choice. Measuring instruments with a remote probe are better suited for measurements in hard to reach or narrow places, and display lighting can also be helpful.
Measuring range and measuring accuracy are important . Both must be tailored to the intended purpose. Devices with two-point calibration always provide a more accurate measurement of the slice thickness.
Relatively low-cost, entry-level coating thickness meters are often sufficient for measuring the coating thickness of the paint coating on vehicles, but they are almost always suitable only for steel sheets and not for aluminum body parts.
Our practical tip: Create ideal measuring conditions
All surfaces must be clean and dry during measurement. Minimum material thickness and minimum required measuring surface must not be undercut to avoid measuring errors. Similarly, any curvature of the surface must not be less than the minimum allowed radius of curvature. Before each measurement, a zero point calibration should be performed on the meter using a non-coated material sample to achieve the highest possible accuracy. Also make sure to select the correct measuring mode for ferromagnetic surfaces or non-ferromagnetic materials.
FAQ – Frequently Asked Questions about Film Thickness Meters
Paint is often made up of several layers – what was the result of the ich?
Regardless of the structure of the coating, the thickness of the entire coating layer is always measured and displayed as, for example, the sum of filler, primer, top coat and clear coat.
How do ich find out if the base material is an iron metal (Fe) or a non-ferrous metal (NFE)?
A simple method is a test with a commercially available, small magnet: If it sticks to the test object, it is an iron metal. If there is no attraction force, a non-ferrous metal must be assumed.