Reply to Peter Davies
Peter
I anodized my bits a few weeks ago. I found Andy Draper at Europa to be very
helpful on the subject. What you need is chromic and NOT sulphuric anodizing.
Your parts should only be anodized to a depth of 2 microns, Andy can tell you
the correct DEF STAN specification to ask for when you speak to your anodizer.
Sulphuric anodizing is more suited to double glazing parts etc where fatigue
is not a problem. The depth of anodize can be upto 50 micron which gives a
hard surface which wont corrode but this is not suitable for aircraft parts
because of the affect on fatigue life.
There is no need to anodize any parts that are entirely buried in the
structure.
You may be asked if you want the bits sealed. This makes the surface less
porous and therefore less prone to corrosion but also reduces the the adhesion
properties. Even so the adhesion properties after sealing are still better
than for the raw alloy. The various parts are made of 3 or 4 different alloys
but they can all be treated in the same way as far as anodizing is concerned.
Again Andy can tell you what these are if you need to know. After anodizing it
is still advisable to paint any exposed metal because the surface can easily
be damaged.
Having read all that you may be wondering if it is worth the bother. My own
view is that the #35 it cost me gives me a little more peace of mind, but I
doubt if it is really necessary if the parts are painted properly.
Hope this helps,
Paul Atkinson (237)
E-mail from: PAUL ATKINSON, 01-Mar-1996
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