Re: Round bar immersion Inspection There are three approaches to creating a helical scan. (which just means that the probe covers the bar in a helical pattern, i.e. like a screw thread)
The Bar is on a skewed conveyer system with a fixed probe assembly. I.e. the bar rotates and moves forward evenly.
This works well for large tubes, (up to maybe 200mm diameter, maybe 10-20 m long) as part of an in-line conveyor system. The conveyor needs to be well set up and large, but, being fixed, the ultrasonic set up, is relatively simple to arrange.
second method is to have a rotating test head, through which the bar is moved. The test head is expensive, and setup is critical, but it can be fast
and very effective. It is the only way to test continuous product, i.e. coiled rod or wire.
Lastly you can rotate the bar and scan the probe along. This is most typically used for small bars, in an immersion tank. Typically there is much less vibration, so it works well for small critcal parts, which need to be tested to a high sensitivity. It is normally used for small batches, rather than high volume production.
Which of these works best depends on many factors, there is no one best way.
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: Could anyone explain what is the best way these days to to immersion testing on round bars as there are different scan patterns like one is helical and another is bar rotates and transducer is ondexes in linear direction. Which is good? and what really is helical scan?
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