MAX II
Bolt Tension Monitor
149
3) Press the
LEFT
and
RIGHT
arrow keys multiple times using the right
button wheel to scroll the value. When the correct threshold is being
displayed,
proceed to step 8
.
4)
Alternatively
, press the
ENTER
key to display the
Digits Edit Box
.
5) Press the
UP
and
DOWN
arrow keys multiple times using the left or
right button wheel to scroll the highlighted value.
6) Press the
LEFT
and
RIGHT
arrow keys multiple times using the left or
right button wheel to scroll the digit locations.
7) Repeat steps
5 & 6
until the
Threshold
number is correctly displayed.
8) Press the
OK
key to set the
Threshold
and return to the menu screen, or
ESC
to cancel entering the
Threshold
.
9) Finally, press the
MEAS
key to return to the measurement screen and
begin taking readings.
12.7 Interpreting the Waveform
One of the most important things to consider, when using the
MAX II
, is how to
interpret the waveform in order to choose the proper phase (polarity) and gain
setting. It’s also important to understand what’s taking place during a basic
measurement. The user has the option of selecting the phase only once during the
L-REF
(reference length measurement). Once the phase is chosen and the
L-REF
measurement taken and stored for a particular bolt, all the elongation and loads
taken for that particular bolt will assume the sample phase. At first, this might not
seem all that critical. In most cases, with well prepare bolts, this might very well be
the case. While both phases may look fine at first sight, during the
L-REF
mode,
deformations in the joint can occur when a load is applied to the bolt.
When a load is applied on a bolt, the velocity of the fastener decreases. Any
deformations in the joint (bending) will disrupt the sound path and potentially cause
an overall decrease in signal amplitude. When this occurs, the decrease in amplitude
can cause the
MAX II
to lose the first cycle altogether. If the fist cycle is lost, the
MAX II
will “peak Jump” to another cycle later in time with greater amplitude. Often
times the transducers have a very slow ramp up time in their construction. In other
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