Checkline TI-007DLX, Руководство по эксплуатации

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Measuring laminated materials
Laminated materials are unique in that their density (and therefore sound-velocity)
may vary considerably from one piece to another. Some laminated materials may even
exhibit noticeable changes in sound-velocity across a single surface. The only way to
reliably measure such materials is by performing a calibration procedure on a sample
piece of known thickness. Ideally, this sample material should be a part of the same
piece being measured, or at least from the same lamination batch. By calibrating to each
test piece individually, the effects of variation of sound-velocity will be minimized.
If the variation is relatively close, averaging the sound velocities to minimize error is
another option.
An additional important consideration when measuring laminates is that many included
air gaps or pockets which will cause an early reflection of the ultrasound beam. This
effect will be noticed as a sudden decrease in thickness in an otherwise regular surface.
While this may impede accurate measurement of total material thickness, it does
provide the user with positive indication of air gaps in the laminate.
Measuring through paint & coatings
Measuring through paints and coatings are also unique, in that the velocity of the paint/
coating will be significantly different from the actual material being measured. A perfect
example of this would be a mild steel pipe with .025” of coating on the surface. Where
the velocity of the steel pipe is .2330 in/μsec, and the velocity of the paint is .0850 in/
μsec. If the user is calibrated for mild steel pipe and measures through both materials,
the actual coating thickness will appear to be approximately 3 times thicker than it
actually is, as a result of the differences in velocity.