Wow, I did not realize that I had such a reputation.
Shot peening a metallic surface indeed creates a "skin" in compression thus
partially countering any applied tensile load, which in turn makes the part
less susceptible to crack propagation. It can also "sort of" close minute
cracks that could lead to failure, in a fashion similar to how drilling a
small hole at the end of a visible crack stops the growth of the crack by
forming a blunt end to the crack (crack propagation is more aggressive when
the crack end is sharp).
In other words, I concur.
However, I am less certain that bead or grit blasting can remove the power
coating on the engine mount, and I don't know enough about the coating to
know if it can be removed chemically, but I do know that it is a mix of
pigment and resin that is cured at elevated temperature, and that suggests,
but is not conclusive, that the resin is an epoxy (or other chemically
cross-linking) system which is not likely to be dissolved easily (if at
all). It definitely chips easily enough though, so beating on the thing
with a spray of glass beads may work after all. I'd certainly try.
Best regards,
Rob Housman
Europa XS Tri-Gear A070
Airframe complete
Irvine, CA
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of Alexander
Kaarsberg
Subject: Europa-List: Removing Paint from Engine Mount?????
<kaarsber@terra.com.br>
Tony
Bead blasting is OK it makes the part stronger if done carefully, (by
compression the surface and stretching the inside, oversimplification! )
Grit blasting is dubious.
Graham
-- beadblasting and flappeening are techniques employed when surface
hardening is desired, it is a gentle way of coldworking a metal
surface- but while it hardens the surface, it would also become more
brittle.
Whether an engine mount would benefit from that or not would be
interesting to learn from our resident and always helpful
metallurgist, the good Mr. Housman?
Alex #529
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