FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

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effect of the last two could be averaged out by having each ball run through
the test several times but this is not necessary to achieve satisfactory
success rates. Other factors that widen all the distributions are
controllable to a degree. These are: velocity of the incoming ball,
direction of impact and location of impact on the anvil. All these
parameters are rerated to the trajectory of the incoming ball. The more
repeatable it is, the finer the distributions will be. This allows the gain
to be increased, moving the good ball distribution closer to the threshold
and thus pushing the cracked ball distribution further away from it. The
distributions obtained with this prototype were narrow enough to obtain very
good success rates (97X of cracked balls recognized with no good balls
misdiagnosed). However, one parameter in particular, ball velocity, varied
significantly and is believed to cause most of the spreading of the
distributions. A significant improvement is expected when the feeding
system is redesigned to fit a tester on the production line.
ACKNOWLEDGEMENTS
The author wishes to thank Mr. Ghislain Vaudreuil of the Industrial
Materials Research Institute and also Mr. George Chapman of the Steel
Company of Canada for their precious contributions to this work.
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