Surface World May 2019 Surface World May 2019 | Page 41

Since the unit is able to automatically determine the substrate and use the appropriate measurement circuit, this enables instant, non-destructive testing on painting, plating, anodising, and organic coatings with accuracy up to 0.1 um. Such testing takes less than a second to display the measurement. Because the key to providing accurate, repeatable measurements is the operator’s ability to reliably make consistent contact between the instrument and the test surface, the unit also utilises a spring-loaded probe to generate a consistent contact pressure with the measured surface. This integrated probe also includes built in edge guides to enable easy measurement of even curved and edged surfaces. To ensure device stability during measurement, the foot of the probe is also designed to provide a firm platform when placed onto the test piece. According to Bogart, a number of other design considerations in handheld coating thickness gauges can also simplify measurement and improve versatility. Simplifying Coating Thickness Measurement Although traditional laboratory and online based coating thickness measurement techniques are useful in the right settings, they have lacked the simplicity and flexibility required for frequent spot checks. Often, this involves sampling, sample preparation, and taking the sample to the lab for evaluation, which requires the participation of staff adequately trained for the process. Other conventional coating tests, such as scratch testing, have been destructive or invasive and damaged the sample. This meant that a product could not be returned to the production line, or that a coated surface had to be recoated or repaired in the field at additional expense. Also, since only a small portion of the component or facility may be tested, results may not be representative of the entire situation. Consequently, various portable coating thickness measurement devices have been developed. However, these have not always provided the necessary accuracy or been sufficiently easy to use. twitter: @surfaceworldmag Another drawback is that in certain environments with multiple substrates, the devices typically either had difficulty determining the substrate or utilising the correct test for the application. So, multiple measurement devices had to be used, which complicated testing and added cost. Finally, typical coating measurement methods were usually unable to accurately measure curved or complex surfaces. This left pipe as well as convoluted component designs largely unable to be easily spot checked for coating compliance. In response, industry innovators have developed a number of advanced designs for handheld coating thickness test devices. For units used on the production line and in the field, these significantly improve accuracy, versatility, and ease of use. One example, the LZ990 portable coating thickness gauge by Kett combines two of the most widely used measurement methods, magnetic inductance and eddy current, in a dual mode device that can measure the coating thickness of almost any non- magnetic coating on both ferrous (magnetic) and non-ferrous (non-magnetic) substrates. In order to improve accuracy and durability on the factory floor or in the field, it is best for the unit to have no moving parts, other than the probe. Similarly, the unit should be impervious to vibration, with measurement independent of its orientation. To save time during the testing process, he recommends utilising a unit with a large screen that enables the quick reading of results. Those results should be able to be stored in the gauge and transferred to a computer and/or printer for documentation and averaging purposes. An instrument that stores many test measurements is best so operators can perform numerous tests before downloading the results. “Easier, more accurate coating and plating measurement with handheld units will help to improve quality checks wherever needed,” concludes Bogart. “So, defects can be immediately detected and corrective action undertaken to minimise scrap and faulty end-products.” For more info, contact Kett Email: [email protected] Visit: www.kett.com. MAY 2019 39