In a message dated 9/20/99 6:42:53 AM Pacific Daylight Time,
monadnoc@crystal-mtn.com writes:
<<
>
> I had a machine shop miss cracks with magnaflux. They didn't clean it well
> enough first. I sold a used head with no crack guaranty. I had to eat
that
> one.
Bob brings up a good point here. Magnafluxing is effective only if the
person
doing the job is properly trained. The head or block must be completely
cleaned
of all oil and grease first. Even paint can mask magnaflux indications.
Using
the alternating current method, magnaflux will find cracks that come to the
surface of the part. The direct current method will locate sub-surface
defects,
but only down as far as 1/8" or so. And it's much more difficult in
interpretation. These 2 methods use a dry, visible powder, but there is
also a
wet bath method used with a "black light" and flourescent solution to show
crack
locations. I have been doing these testing methods in the nuclear industry
for
20 years, and we need 3-6 months of training to be properly qualified in the
industry. BTW, Magnaflux is a brand name of non-destructive testing
materials.
The proper terminology is magnetic particle examination, but like Scotch
Tape,
Magnaflux has become the accepted terminology.
Wally / Templeton, MA
53 3100 rod project >>
Wally,
Brings up a question, in your opinion, how well do the flux kits sold from
Napa work? I've used them in the past to check for cracks between exhaust
seats, and assumed I was getting my money's worth.
Mike
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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