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From [log in to unmask] Tue Jan 21 12: |
29:08 1997 |
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The issue came up this morning with a customer of mine as to why I
would want to deviate from his specification calling for alternating
the grain direction in the layup of a 6 layer MLB. I could'nt give
him the answer he was looking for. It seems that in all his
experiences, other vendors require cross graining to avoid warp and
twist and that keeping grain direction constant was a no, no.
In all of my experiences the case has been just the opposite. WE
go out of our way to assure that materials are cut to order in the
proper direction so we can avoid cross graining. Maybe this practice
started years ago by recommendation of our laminate supplier, or
maybe after making many orders of "potato chip" boards we decided to
watch the grain directions of our layups.
My thoughts on the advantages of NOT cross graining are:
1. Predicable shrinkage compensated by scaling the artwork.
2. No built in stresses from lamination thus less twist, warp in
subsequent processes.
Can anyone please ellaborate on this issue.
Thank You.
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