[DML] Re: Thread Galling

["David Teitelbaum" <jtrealty@xxxxxxxxxxx>]

Galling can be fatigue corrosion too. It is really fretting and
results from overcycling metal. In threads it can appear because of an
under-tightened fastener. It can also appear when using dissimialar
metals in the presence of an electrolyte like water. Very common in
aircraft which are exposed to weather and high stress loads with a lot
of cycles. Aircraft also have many different types of metals. This is
one of the reasons you will see recomended that you use an anti-seize
compound on the spark plugs. A highly stressed fastener, steel, in
aluminum. The spark plugs ARE plated to help prevent corrosion but
that is not enough. Look up the electomotive chart. The farther apart
2 elements are the more reactive they will be in contact with each
other. It has to do with their affinity for trading electrons.
Electrolytic corrosion is really an electrical plating (or deplating)
process. Fretting corrosion is a welding process. The 2 pieces of
metal are brought into intimate contact with heat and pressure and
separated may times creating the "corrosion" you will see.
David Teitelbaum
vin 10757


--- In dmcnews@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> wrote:
> Just received an eMail Re: thread galling that shows there still is
> misunderstanding about what it is:
> 
> Galling is NOT a problem that develops over time





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