And—to add to Chris' input, and the measuring uncertainties, the 75% fill requirement is totally arbitrary without any technical justification in terms of performance.
Werner
-----Original Message-----
From: Chris Mahanna <[log in to unmask]>
To: [log in to unmask]
Sent: Wed, Nov 11, 2009 1:27 pm
Subject: Re: [TN] Measuring hole fill
Elaine,
I like the question, as the answer can be a little more complicated than most
expect. The metrology of the hole fill requirement is external visual
assessment unless otherwise mandated by procurement documentation. As a
test-n-measure lab (trying to stay away from the pissing match) we often "warn"
our "user side" customers that the evidence they collect by microsection or
x-ray may not be enforcable/practicable. For microsection, the methods require
conformant grinds to be +/- 10% from the center, so once the customer defines
the set of holes, the inspection is set. Sometimes we have to section one hole
at a time and clock it appropriately. Compliant pin caused deformation is
notorius for this problem too.
You need a really nice x-ray/operator/ and a little luck to inspect these things
as we see them in our minds eye. In most cases, I doubt you'll get better than
+/-5% uncertainty, which unfortuneatley in the world of class 3 independent
inspections, ain't going to cut it. Of course it is a little ironic because
-what was the uncertainty of the initial external observation? Thank goodness
that very few require compliance with ILAC G-8 "Guidelines on Assessment and
Reporting of Compliance with Specification (based on measurements and tests in a
laboratory)"
Good luck.
Chris
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brown, Elaine
Sent: Wednesday, November 11, 2009 12:23 PM
To: [log in to unmask]
Subject: [TN] Measuring hole fill
Good afternoon
How do you measure holefill to assess the 75% requirement.
I know it is by cross section,
--but is it the single plane of the section(all voids count as missing even
though you can
see that you have sectioned into a void and it is filled underneath)
--portion of the hole filled( even though there may be some small voiding on the
surface plane)
And if you are trying to use single plane, how do you assess 75%--visual
estimate?
I think the portion of the hole would be easier to measure, but would it still
be a visual
estimate.
Thanks in advance
Elaine
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