Dakota Ultrasonics MMX-6DL User Manual

Page 19

MMX-6 DL Ultrasonic Thickness Gauge

6) While the transducer is firmly coupled to the probe-disc, press the

PRB-0 key on the keypad. The MMX-6 DL will display "Prb0"

while it is calculating its zero point.

7) Remove the transducer from the probe-disc.

At this point, the MMX-6 DL has successfully calculated it's internal

error factor, and will compensate for this value in any subsequent

measurements. When performing a "probe-zero", the MMX-6 DL will

always use the sound-velocity value of the built-in probe-disc, even if some

other velocity value has been entered for making actual measurements.

Though the MMX-6 DL will remember the last "probe-zero" performed, it is

generally a good idea to perform a "probe-zero" whenever the tool is turned

on, as well as any time a different transducer is used. This will ensure that

the instrument is always correctly zeroed.

Calibration

In order for the MMX-6 DL to make accurate measurements, it must be

set to the correct sound-velocity for the material being measured. Different

types of material have different inherent sound-velocities. For example, the

velocity of sound through steel is about 0.233 inches-per-microsecond,

versus that of aluminum, which is about 0.248 inches-per-microsecond. If

the tool is not set to the correct sound-velocity, all of the measurements the

tool makes will be erroneous by some fixed percentage. The one point