Bob,
You wrote
>>X-ray or
>neutron beam analysis is much better, but don't try this at home ;-)
>
>Philip E. Barnes '71 TR6 CC61193L
>Can't I pick up a neutron flashlight or some such at K-mart???
I think they keep them over with the Power Rangers toys.
Jim
P.S. This has been one of the more entertaining threads lately. On the
subject of crack testing, there are several technologies available, all of
which originated in the welding industry for detecting imperfections in
welds. The most commonly used methods in the automotive industry are
Magna-flux and Dye Penetrant.
In the Magna-flux process a large DC current is passed through the part being
tested such as an engine block, head or crank. The current source is very
similar to a DC welder. The electric current sets up a magnetic field in the
part (it only works on iron based parts). Cracks cause a distortion in the
magnetic field, which is clearly visible when fine iron filings are sprinkled
over the part.
In the Dye Penetrant method, a dye is sprayed on the part and allowed to set
for a minute or two. It is then cleaned off with a solvent, then either a
white, absorbent material is sprayed on (red dye) or an ultra-violet light is
shined on the part (yellowish green spray). This method is easy to use, and
inexpensive, but it doesn't detect cracks beneath the surface.
are not normally found at the local machine shop, or at K-mart. Most machine
shops have a Magna-flux setup, and you can buy the Dye Penetrant at your
local welding supply house. Have fun,
Jim Harroun
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