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 49078
Temperature effects on Anodized Aluminum
Parts
June 19, 2008
Our company current heat shrinks several aluminum parts together
and we are thinking about requiring a hard anodized surface on one of
these parts. This surface is also a sealing surface for a gland type
o-ring detail. My question is that if we hard anodize the part, what
is the maximum temperature we can apply to the part for heat
shrinking and not see any surface degradation or cracking which could
cause a leak?
Brett Blanchard
Engineering - Knoxville, TN
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June 20, 2008
Look up the coefficient of thermal expansion for your
aluminum alloy and for aluminum oxide. BIG difference and
the hard anodize will probably crack and possibly
delaminate.
If the inserted part is not anodized, look into shrinking it
by using liquid nitrogen and rapidly press that part into a
warm larger part. Wonderful shrink fit after they reach room
temp.
Dry ice and alcohol get quite cold also, but not as much as
liquid gasses and probably cost as much in the long
run.
Safety measures are mandatory for both.
James Watts
- FL
June 20, 2008
Sheasby and Pinner
say, "fine cracks may be observed at 80-100C - - cracking is
caused by the low coefficient of expansion of the anodic
film which is approximately 0.2 times that of the metal,"
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