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Existing ultrasonic bolt gages are limited in reliability and resolution because they only use one point (one zero crossing) in the whole reflected waveform.  Distortions in the echo can cause "peak-jumping" without your knowing it.

Background:
Ultrasonic bolt gages transmit a sound pulse (ultrasonic) into one end of a bolt and listen for the echo (like sonar). When you tension the bolt it takes a longer time for the echo to return (the bolt stretches and the speed of sound slows down).

For over 30 years, bolt gages have measured this “echo time” by starting and stopping a counter (clock).  The counter is started when the ultrasonic pulse is sent out, and the counter is stopped using a single zero-crossing event, in the return echo, as shown in the Figures below.  Tension often induces distortion of the echo which can cause the clock to miss a peak with NO display indicating that this peak jumping has occurred.

SureBolt^TM outperforms all other bolt gages by using all of the return echo’s data.  This increases the reliability and accuracy dramatically.  The entire reference echo is recorded and compared to the entire new echo when you tension the bolt.  

SureBolt^TM’s screen graphically overlays and displays the two echoes and lets you see any distortions that tensioning might cause.  Some distortions are caused by moving the ultrasonic transducer (slipping, off center, loss of coupling, ...), and other distortions are due to the actual tension in the bolt that deforms the surface of the bolt. 

With SureBolt^TM , if there are distortions, you will know this immediately!

Because of the distortion factor, some existing “one point” bolt gages include a built in scope to let you see the echo’s strength.  But they still only use one point, and they do not store the zero tension’s entire echo. So how do you tell if the new echo is distorted?

See the figure to the left and guess which zero crossing (yellow or green dot) the "one point" bolt gages will use.  Answer:  The first small peak grew and will cause the "one point" bolt gages to read far less tension than is really in the bolt.  

See the second echo's distortion in the animation above. See comparison table.

SureBolt^TM stores enough information for each bolt to make the reliability of each measurement much more obvious.  SureBolt^TM uses the familiar Windows 98/2000 user interface to record and play back data.

NASA compares SureBolt^TM to one point bolt gage

Short bolts, weak echo bolts, and bolts that distort the echo when they are tensioned are unreliable with one-point bolt gages.  For example, the CBM Attach Ring bolts used to hold NASA’s Space Station together were too short and the echoes were too weak for the one-point bolt gages to be very reliable.  The pressure test, using the "old technology" bolt gages, was difficult. With SureBolt^TM it became easy.   

On the next test, a SureBolt^TM prototype was used on 6 bolts, and it was fully reliable at all tensions.  The SureBolt^TM prototype readings were directly compared to the one-point bolt gage readings for each of the next 5 tests.  

After the third test, NASA stopped requesting the data from the one-point bolt gages and relied solely on the SureBolt^TM prototype because SureBolt^TM outperformed the one-point bolt gages on every bolt and every test in reliability and accuracy.

For more details on the technical innovations of SureBolt, see the comparison table.

Back to the main SureBolt^TM navigation screen.

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