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.
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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.
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