Yeah, Radiographing is mostly used for detecting welding flaws. Like when
the welder lets the tig electrode touch the puddle and leaves a trace of
tungsten. In portable applications it's done with a PIG, which is a
shielded container with a Cobalt60 gamma source inside and a shutter.
Anyone who knows anything about radioactive materials is scared spitless
of cobalt60. It's not something you find in a home shop, thank God.
You will find dye penetrant in home shops. You need a clean surface that's
not too rough to do good dye penetrant testing. It's simple, you spray on
a penetrant material, clean off the surface with a supplied cleaner, and
spray on a light colored (usually) developer. On bad cracks you'll see the
dye come right up and color the developer. Smaller flaws require UV light
to see them.
Magnaflux takes advantage of the orderliness of magnetic lines of flux in
continuous material. You spray or paint on the fluid (sometimes a powder
is used) and zap the part with a fairly high current at low voltage--AC or
DC. Any cracks show up because the magnetic flux generated in the part is
interrupted and the interruption moves the material around. You can sort
of do magnaflux with a welder and a bit of practice. It doesn't seem to
hurt the welder. I haven't tried that for years, but I did a lot of it
back when I was building and racing motorcycles. Failures on racing
motorcycle suspension tend to be even more catastrophic than cars.
There are a host of other approaches for NDT, including eddy current
testing, MRI, etc. Most of them are for airplanes, bridges, train tracks
and such stuff.
-----Original Message-----
From: WEmery7451@aol.com [mailto:WEmery7451@aol.com]
Sent: Friday, January 31, 2003 8:22 AM
To: Bill Babcock; spitfiresuz@141.com; bownes@web9.com; fot@autox.team.net
Subject: Re: X-ray of parts
In a message dated 1/30/03 4:53:12 PM Pacific Standard Time, BillB@bnj.com
writes:
<< Dye penetrate testing is fun, but stay away from discos for a while
after you do some. You'll light up like a searchlight. I always manage to
get it all over myself.
>>
I was dye checking front hubs for a while in the late 60's and early 70's
after breaking a hub at Summit Point, tearing off the left front fender,
and
twisting up the original, optional, light front sway bar that ran under
frame
like a pretzel. I actually did find another couple hubs with surface
cracks.
As Bill would know, radiographing is used in Nuclear Plants for checking
stainless steel piping and welds. My guess would be that 95% of racing
part
failures result from fatigue, which start with surface cracks.
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