NDT Vita Fórumok

I'm using a 5 Mhz transducer with a PWR OF 100ns can this number be changed to tune in a signal also what about damping I've always used what is approiate for the lead attached and I'm being audited and the person doing the auditing changes parameters so that his A-scan signal increases such as having a 5 Mhz transducer with a setting for a 1 Mhz there are many issues I'm having with his calibration I use the Omniscan manuals to set up my equipment and he "doesn't care what the book says"can I gget some other information to combat this or do I have to take it ?digitizing,PWR,Frequency settings, or all being changed to increased to "tune in " the signal I know that there should be standard setting for the purpose of repeatability as well as general accepted practices. but the person I'm dealing with seems to have the ability to do what he wants with the machine settings is this acceptable can I get information to combat this or what should I do

We need a lot more information before we can give a full reply here. For example, what instrument are you using (an OmniScan PA or UT), what damping settings etc.? As for the debate on settings with the auditor, there are no set-ups "cast in stone", i.e. the operator or auditor can always change a standard set-up in principle. However, running a 5 MHz transducer with a setting of 1 MHz seems a bit unusual. While this may give higher gain under some circumstances, this may lose some other benefits such as resolution or sensitivity. Gain is not usually a problem with our instruments. Suggest you e-mail me at michael.moles@olympusndt.com with your full set-up, and we'll go from there.
Yours,
Michael

It is always up to the user to determine the setup parameters and test procedures that are appropriate for their needs, and verify performance on appropriate reference standards before performing tests. It sounds like you have some internal issues that are beyond the scope of this forum... anyone who says he "doesn't care what the manual says" is certainly working at his own risk and may or may not be getting valid test results.

From the manufacturer's perspective, the normal approach would be to drive a transducer at its center frequency, like 5 MHz for a 5 MHz transducer. That will usually produce the cleanest response. It is certainly possible to drive down the center frequency by pulsing at a lower frequency, but that is an unusual approach and may cause significant waveform distortion. Filtering and damping will also have an effect on the shape of the signal. The most important thing is to verify to whatever level is required by your company's procedures that the instrument and setup are doing what you need them to do for a given test.

Hi friends i'm a student,we have omniscan mx in our college.i just want to know is c scan possible using UT and can it scan composite materials. can any one help

Yes, you certainly can. If you have an encoder, you can scan and collect auditable data to give C, B- and D-scans. If you don't have an encoder, you can scan using free-running and still collect a C-scan. However, you will not get such reliable and auditable data. We inspect composites regularly using normal beam arrays and various wedges for the aerospace industry. The actual array and wedge will depend on the application. If you have more details, send me an e-mail at michael.moles@olympusndt.com.

Michael

Yes, you can perform C-scans of composites with the Omniscan MX in either phased array or conventional UT mode. You will also need an probe that's appropriate for your specific material and thickness range, and an encoder if desired.

We have an application note on the subject at <http://www.olympusndt.com/en/ndt-application/183-id.209715258.html>.

If you're new to C-scanning, you may also wish to review the "Imaging Basics" section of our phased array tutorial at
<http://www.olympusndt.com/en/ndt-tutorials/phased-array/>

it is showing uncorrected c scan when ever i start c scan,what it mean by.?

Not sure about your set-up here. Can you either post some more information on the type of scan you are performing including displays, or contact me directly at michael.moles@olympusndt.com.
Thanks, Michael