Factors To Consider For Accurate Coating Thickness Measurement
Posted on Wednesday, November 25, 2015
The heart of any electromagnetic measurement system is the probe. The probe is a very complex system,
which performs the conversion of the appropriate measurement method to a reading on the corresponding gauge.
Proper selection of the coating thickness instrument and probe will determine the accuracy and reliability of the measurement results.
Addressing each factor is critical to providing accurate results for complex challenges faced by coatings professionals each day.
Curvature Compensation:
One of the most common influences on coating thickness is curvature. A curved part can cause erroneous readings without proper adjustment of the gauge and probe.
The influence of the curvature varies with the make and type of the instrument but becomes more pronounced as the radius of the
curvature decreases. A probe that incorporates the curvature compensation method is ideal.
Edge Effect:
Edge effect is defined by ASTM B244 as being sensitive to abrupt changes in the surface contour of the test specimen.
Therefore, measurements made too near an edge or inside corner man not be accurate unless the instrument is specifically
adjusted for this. Like curvature compensation, adjustments can be made for edge effect.
Surface Roughness:
Surface roughness and base metal reading (BMR) on an uncoated substrate is another factor to consider when measuring
using a coating thickness gauge. "The BMR is the measured effect of substrate roughness on the coating thickness gauge that is caused
by the manufacturing process or surface profile roughness-producing operation." A double-tip measurement probe offers
higher repeatability when measuring rough surfaces. It is important to take multiple readings when measuring rough surfaces.
The curvature of the part, measuring too close to the edge, surface roughness and more can affect the thickness readings of your coatings.
Increasing quality and reducing costs is achievable with a basic understanding of the measurement process.
The extensive selection of FISCHER instruments and probes are as versatile as the measurement applications of our customers.
After years of continuous development and innovation, FISCHER offers over 100 probes designed to ensure optimal results for
the widest range of measurement applications.
Contact FISCHER Today
860-683-0781
info@fischer-technology.com
www.fischer-technology.com