Test Blocks; Transducer Zero Compensation; Figure 5-8 Example Of A Five-Step Test Block - Olympus 45MG User Manual

DMTA-10022-01EN, Rev. C, January 2015
5.2.2

Test Blocks

The 45MG comes with a cylindrical stainless steel test block with two thicknesses.
Two precisely known test-block thicknesses can be used to perform the material
sound velocity and the zero calibrations.
Precision step test blocks are also often used when more than two known thicknesses
are needed (see Figure 5-8 on page 58).
When performing the material sound velocity and zero calibrations, you must use a
test block with the following characteristics:
• Made from the same material as the part to be tested.
• Has two or more precisely known thicknesses.
• Has one part as thin as the thinnest section of the parts to be tested in order to
perform the zero calibration. The surface condition should be similar to that of the
tested parts. Rough surfaces generally reduce the accuracy of measurements, but
simulating actual surface conditions on the calibration block can help to improve
results.
• Has one part as thick as the thickest section of the parts to be tested, in order to
perform the material sound velocity calibration. The front and back surfaces
should be smooth and parallel.
• Be at the same temperature as the samples to be measured.
5.2.3

Transducer Zero Compensation

Perform a transducer zero compensation by pressing [2nd F], [CAL ZERO]
(Do ZERO) whenever the zero indicator (Do--) appears. This procedure should also
be performed when the dual element transducer temperature has changed.
58 Chapter 5

Figure 5-8 Example of a five-step test block