Conductive and non-conductive coating thickness measurement and testing skills

Both conductive and non-conductive coating thickness measurements require precision. The importance of accurate coating measurements in the aerospace industry cannot be overemphasized, as loss of coating material can affect safety standards and can lead to dangerous failures. Even a small loss of thickness can cause the asset to degrade over time until the situation becomes critical.

That's why non-destructive testing (NDT) is an essential part of routine aircraft maintenance. Coating thickness measurements using good non-destructive testing methods and equipment help ensure that no defects go undetected and enable analysts to make repair or replacement recommendations early on, preventing larger complications (which can be costly to resolve) many). The following tips can further help analysts enhance and simplify detection workflows for good results.

Conductive Coating Thickness Measurement Tips

Since conductive coatings can be applied by lamination, spraying or painting, they are a sensible option for retrofitting or upgrading aircraft without changing materials. Conductive coatings such as silver, copper or molybdenum transfer heat and electricity to protect against hazards such as lightning strikes or freezing.

Any loss of coating thickness can negatively affect the integrity of the coating and expose the substrate layer to a number of hazards. Icing is particularly dangerous because it changes the aerodynamics of the plane and increases its weight to the point that it is too heavy to handle safely. Additionally, thin or damaged conductive coatings can expose sublayers to corrosion. Therefore, analysts need an instrument that can measure changes in thickness while pinpointing areas of potential corrosion.

1: Choose good non-destructive testing equipment

To detect thinning early and prevent more dangerous complications, analysts need sophisticated instruments specifically designed to measure the thickness of conductive coatings. Older or substandard instruments may cost less to buy up front than higher quality alternatives. However, using inferior equipment may incur greater costs in the future, as it increases the risk of analysts overlooking certain hard-to-detect defects until they become more prominent problems that require more expensive solutions.

2: Use a modular measurement system

The correct conductivity measurement system depends on various factors such as coating type and material type. But one commonly used method for conductive thickness coatings is the Modular Measurement System (MMS). In addition to substrate materials, the modular system also automatically measures conductivity and thickness. Furthermore, MMS integrates various modules, allowing for flexible techniques. For example, there is one module for testing the thickness of zinc-nickel coatings on non-ferrous materials and another for copper coatings. Another module enables non-magnetic coatings on metals such as copper or zinc using magnetic induction and eddy current measurement techniques.

3: Use eddy current testing when appropriate

Eddy current testing (ECT) can also be a useful method of measuring the thickness of conductive coatings if the upper layer of the coating is non-magnetic.

Ultimately, the best method for detecting the thickness of a conductive coating is a case-by-case basis.

Non-Conductive Coating Thickness Measurement Tips

A non-conductive coating protects components from overheating, overcharging and corrosion. For example, if you coat steel with a coat of epoxy, the non-conductive paint can protect the steel's subsurface from acidity or rust. The thinner the coating, the more exposed the part is and the more likely it is to suffer damage such as thermal fatigue or warping.

1: Use eddy current testing for non-conductive coatings

Eddy current testing is one of the best methods for measuring non-conductive coatings , as it can test anodic coatings, as well as most non-conductive coatings on non-magnetic base metals. ECT instruments have features that simplify the detection process and generate comprehensive data. Additionally, ECT instruments are more likely to produce fast, accurate results due to enhanced technology and software. Modern ECT instruments and scanners with high signal-to-noise ratios (SNR) tend to require more intensive setup and cleanup than other test methods that can even cause damage to the coating (such as those that require the analyst to scrape a sample from the coating itself for testing) method) is more effective.

2: Merge Surface Array Probing

While even traditional eddy current testing tends to produce higher quality data than other methods, including surface array probing can further improve data quality and test comprehensiveness. Surface array probing can accommodate non-flat surfaces while detecting thickness variations with impeccable accuracy. A good probe includes a high-quality coil pack for increased accuracy and reliability.

3: Using Portable Instruments

To maximize effectiveness and convenience, analysts should be equipped with portable ECT equipment. Handheld devices are at the forefront of eddy current testing, offering analysts greater mobility and the ability to easily access certain hard-to-reach areas without sacrificing high SNR. The high-quality eddy current array handheld instrument reduces inspection time by up to 95% compared to traditional pen-based probing.

Improved Coating Thickness Measurement

More and more people are taking to the skies – airlines carried nearly 4.5 billion passengers to their destinations last year alone. This makes aircraft inspections more airtight than ever. The more comprehensive the components scanned, the safer all those passengers (not to mention the crew).

Whether an analyst is testing conductive or non-conductive coating thickness, utilizing the right technique and nondestructive testing solution for each application is key to success. In all cases, high-quality instrumentation, scanners, and probes help to increase test efficiency and minimize the chance of unnoticed thinning in the coating, which can lead to larger-scale distress on the runway.