Dakota Digital CMX operation manual Known Thickness, One Point Calibration

Dakota Ultrasonics

Known Thickness

Sometimes the sound velocity of a material is unknown. In this case a sample with one or two known thicknesses can be used to determine the sound velocity. As previously discussed, the CMX has a one or two point calibration option. The one point calibration option is most suited for linearity over large ranges, as noted above. The user should also consider calibrating on high side of the intended measurement range, when using the one point option, minimize overall error. For example, if the measurement range is .100” (2.54mm) to 1.0” (25.4mm), the user should calibrate on a known thickness sample close to 1.0” (25.4mm). Note: It’s always handy to carry a set of mechanical calipers to use in conjunction with the CMX for calibration in the field:

One Point Calibration

Note: Be sure that the probe zero procedure has been performed prior to

performing this calibration procedure.

1)Physically measure an exact sample of the material or a location directly on the material to be measured using a set of calipers or a digital micrometer.

2)Apply a drop of couplant on the transducer and place the transducer in steady contact with the sample or actual test material. Be sure that the reading is stable and the repeatability indicator, in the top left corner of the display, is fully lit and stable. Press the MENU key once to activate the menu items tab. Press the MENU key multiple times to tab right and the

48