Posted by Dennis A. Pearson (184.108.40.206) on 16:51:40 05/09/05
In Reply to:Re: Embedded Aluminum oxide grit posted by Gordon England
: : I am having a problem with embedded aluminum oxide
: : grit prior to coating Inconel 718. We think it is
: : coming from a tumble finishing operation prior to
: : sending out for coating. The grit is added to a
: : burnishing media (ceramic)each time the barrel is
: : filled. Could adding too much grit cause a build-up
: : that could cause this problem? Would the tumble process have enough energy to cause the embedded grit?
: : What would you use as an inspection method to insure
: : grit is not embedded? Is there a good way to remove
: : the embedded grit on affected parts? Appreciate any help since this has become a very big problem.
: : Thanks
: Hi Dennis
: Are you sure the problem is not from the grit blast surface preparation prior to coating?
: Some grit contamination at the substrate/coating interface is inevitable. Many aerospace specifications quote limits around 20% max grit contamination measured on cross-section through interface.
: Air blast or ultrasonic cleaning may remove some retained grit but not all.
: Magnified visual inspection or possibly seeing what adhesive tapes will lift off.
: Regards Gordon
First thank you for the quick reply.
Since a outside vendor does the surface prepration and coating for us, I have to prove
that we aren't causing the problem.I must insure my parts are shipped in a pristine condition.
I will try your suggestions.
Thanks again for your help.
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