Measuring duplex coatings: Why the new MiniTest sensor makes quality control easier for you

Duplex coating systems provide superior corrosion protection that can safeguard steel for many years. Specifically, a duplex coating system combines two protection methods, typically paint or powder coating over galvanized steel, creating protection that surpasses either system used independently. This exceptional performance makes duplex coatings essential in corrosion protection and automotive engineering. However, measuring these multi-layer systems accurately presents challenges for your quality control process. Traditional measurement approaches often struggle to determine individual layer thicknesses precisely. That’s where new sensor technology makes a significant difference! In this article, we’ll show you how advanced duplex coating measurement solutions simplify your quality control workflow, ensuring the precision and reliability you need for long-lasting corrosion protection.

The traditional challenges of measuring duplex coatings

Measuring duplex coating systems with conventional instruments is not as easy as that as the principle of measurement to be used is dictated by the substrate of the measuring object.

The conventional method employs a combination magnetic and eddy-current probe. You take two readings: first in eddy-current mode for paint thickness, then in magnetic mode for total coating system thickness. Then, you calculate zinc layer thickness from the difference.

What makes this sensor different

The new sensor FN Duplex that is now introduced by ElektroPhysik as a supplement to the wellprove line of coating thickness gauges MiniTest 700 solves these measurement problems through simultaneous dual-principle technology. Specifically, it measures the individual thicknesses of both paint and zinc layers in a duplex coating system with a single reading.

Here’s how it works. The sensor utilizes both magnetic (ferrous) and eddy current (non-ferrous) principles at the same time. The magnetic principle measures the combined paint/zinc thickness over your ferrous substrate, while the eddy current principle measures the paint thickness over the non-ferrous zinc coating. The zinc thickness is calculated by subtracting the paint thickness from the combined paint/zinc thickness measurement.

This new sensor works with all three types of zinc used in duplex coating systems: hot-dip, electroplating, and zinc spray metallizing. Measurement starts at a minimum zinc thickness of 0.45 mil or 11 micron.

When not in duplex mode, you can use the MiniTest gauge like a conventional combination ferrous/non-ferrous instrument.

Practical benefits for your quality control process

Switching to the new Duplex sensor streamlines your inspection workflow significantly. Your team completes measurements in one step rather than juggling multiple readings and manual calculations. This efficiency matters when you’re inspecting large structures or multiple parts.

The duplex sensor works in combination with a gauge of the MiniTest 700 series. This line of coating thickness gauges offers statistical evaluation of the readings taken as well as possibility to transfer data to PC.

The device is operated using a menu on a graphic display. Instructions and help text in 20 languages guide you through the settings. Predefined calibration processes help you to calibrate according to international standards (ISO, SSPC, etc.). And a special measurement mode is available to optimise measurement on abrasive surfaces.

Data transfer is equally simple and convenient. You can transfer readings saved on the MiniTest 725/735/745 devices with complete ease to PCs, tablets or smartphones using a USB or Bluetooth connection. You can save up to 10,000 readings on the MiniTest 725 and 735 devices and up to 100,000 on the MiniTest 745.

This gives you the option to record readings on site that you can then analyse and archive at a later date.

Conclusion

Accurate duplex coating measurement doesn’t have to be complicated. As has been noted, this sensor technology eliminates the guesswork and multiple-reading hassle of conventional methods. You get precise measurements of both paint and zinc layers in a single step, streamlining your quality control process significantly.

Undoubtedly, speed and accuracy matter when protecting steel from corrosion. Choose a measurement solution that delivers both, and your inspection workflow becomes simpler while your documentation stays compliant.