04:05 Oct-06-1998 Ed Ginzel R & D, - Materials Research Institute, Canada, Joined Nov 1998 1208
Rolf asked that I take the discussion outside the introduction so I am re-starting the discussion with my reply here.
In the reply to my comment on adding TOFD to a system Rolf suggested that developent costs were a factor. This is true in the beginning but after 25 years of development (in some cases) the costs are recovered.
But this is not what I was implying. In my statement I noted that TOFD is merely forward a scatter UT technique. If a data acquisition system can display B-scans (stacked A-scans) then the data is no different from the PE data acquired, i.e. captured waveforms. TOFD is merely a probe configuration. I also pointed out that linearising and sizing features associated with TOFD displays are Bells and Whistles. By this I mean that these features are nice extras but the data from the pitch-catch probe arrangement need not have the extras to be used as a DETECTION method.
TOFD can be sold as a detection technique or a sizing technique. For flaws of small vertical extent TOFD is not as effective as for flaws of greater vertical extent. Therefore the sizing ability is not ALWAYS so important. However, as a detection technique it is useually VERY effective.