How To Choose A Transducer For An Ultrasonic Thickness Gauge

By Author: Geeta Gusian
Total Articles: 10
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How to choose a transducer for an ultrasonic thickness gauge

The Choice of which Ultrasonic thickness gauge transducersto use is based on a combination of three parameters :
a. Frequency of the transducers
b. Crystal diameter of the transducer
c. Temperature at which the transducer will be utilized

Also, choice of which transducer to use depends on the material for which thickness needs to be measured, approximate thickness of the substrate, physical

parameters of the material that needs to be measured, for ex is it a tube, it is a sheet, is it a block.

The first general guideline to know is that the bigger the crystal dia of the transducer, the more energy can be sent through the transducer allowing thicker sheets of

metal to be measured.

To take an example, a ½’’ transducer operating at 5MHZ allows thickness measurement up to 500m whereas a 3/16’’ dia crystal dia gets you no more than a 50mm range
operating at the same frequency. So this gets you clear on the thickness.

Why, the multiple frequencies, why is 3.5 MHz not the same as 5 not ...
... the same as 10 ?

Back to the law of physics, higher the frequency, the narrower the beam, ; lower the frequency higher wider the beam diameter. Therefore, higher frequencies are more
specifically applicable to thickness measurement of smaller dia or every fine diameter products such as metal tubing whereas a 3.5MHz transducer would get you good
penetration through very thick sheets .

How to choose a crystal dia of an ultrasonic thickness gauge ?

That depends on the kind of material you are testing.

Simply put, always choose a much smaller crystal dia than the surface under test. Whether it is a precision engineering production job, tubing, a pipe or a block ;
choose the crystal dia which allow you to firmly position the transducer onto the object of which your require the thickness.

Where does the temperature factor come in ?

Ultrasonic thickness gauges are affected by high temperatures. If you are working on materials which may be a high temperature i.e 100 deg C or more, specialized
tranducer options are available .

Or more information on choice of an ultrasonic thickness gauge or tranducer, we request you to email your queries to sales@stanlay.com