THE PROBLEM
Commonly the calibration is executed outside the line with disturbed process and bad calibration as a result. Several important factors such as testing speed, probe position, product behaviour etc. are very difficult to simulate. Expensive and therefore often worn out reference pieces will also give a negative contribution. With all problems in mind one can see the reason why calibration some times is not performed.
THE SOLUTION
A working group, within JERNKONTORET, the Joint Nordic Research Organisation, started studying the problem. The project should cover the method ECT on tubes and bars where the members had an interest. The results where reported early 1996.
As a result a new concept based on adding a foreign signal source to the object under test has been worked out. Additional conductive material in the shape of a metal piece instead of absent material from notches and drilled holes should create a more defined signal, with higher reliability to much lower costs. The discussed signal source is by the working group given the name DSA, short for Defined Signal Applicator. DSA will be applied on the running product not affecting the process, working as a "reference to a reference" and thus makes it to calibrate without interrupting the production process.
The results are promising. Much work remains, but for ECT on tubes and for rotating ECT on bars the concept is ready for full-scale application. An ECSC-project has been discussed.
Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00
Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:
Publication Contact:
7th ECNDT, Park Alle 345, DK-2605 Broendby, Denmark, Fax: +45 46 26 70 11, Email: 101373.3414@compuserve.com
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