Chapter Ten Bolt Material Calibration; Why Calibrate; Velocity Calibration - DAKOTA ULTRASONICS MiniMax v2.0 Operation Manual

Ultrasonic bolt tension monitor

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CHAPTER TEN

BOLT MATERIAL CALIBRATION

The preset bolt types in the MiniMax contain average factors for the material type.

These are approximate values only. In a tightly controlled application where extreme

accuracy is required, it is necessary to obtain all the information possible about the

fasteners being measured. By calibrating the fasteners, the ultrasonic and physical

lengths of the bolts will match. However, if a field calibration is done, a complete

calibration is not necessary. An important thing to note is the fact that everything

done in the calibration process result in average values. Since a sample of fasteners

will be used in the calibration process, and given the slight differences in material, the

result will always be an average value of that sample.

A velocity calibration is generally performed by adjusting the velocity in the MiniMax

to the point where the ultrasonic and physical lengths match. Again, since a sample

of fasteners will be used in this process, the velocities will vary by a very small

amount, thus resulting in an average velocity value. To accurately calibrate the

velocity, a calibrated set of mechanical calipers is required to determine the exact

physical lengths of the fasteners. The following procedure outlines this process.

1) Press the

multiple times to tab right, and the

GEOM menu is highlighted and displaying the submenu items.

2) Press the

menu items until QUANTITY is highlighted.

Calibrating the Velocity

key once to activate the menu items tab. Press the

and

arrow keys multiple times to scroll through the sub

key multiple times to tab left, until the

key

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