Thanks for the responses. I had many off-line
responses to my question, here are more details, since
all y'all asked (those who didn't, sorry):
The units in question are cylindrical valve bodies
ranging from 1" to 6" in diameter, 3 to 5 inches long.
The INSIDE diameters are chromed, not the exterior.
The problem material is a rather exotic Rolls Royce
aircraft alloy called RR350, aka Hiduminium, which is
a high temp aluminum (>650F) that is a pain to chrome.
Most chromers hear the word "Hiduminium" and start
convulsing and gagging and foaming through the nose.
We've had it done for 25 years, but everyone seems to
have lost the recipe in the last 5 or 10 years (EPA
hasn't helped). Most chromers can't even plate A356
consistently anymore on the ID. The standard
complaint is bad castings, but then 6061 wrought
equivalents don't turn out so good either. We
generally do not allow an underlayment other than
zincate, but are considering electroless nickel
(QQ-C-320 class II, type 2) allows an underlayment if
it's specified on the print, and you can't consider it
part of the chrome thickness). It's the same old sh!t
as the general Wal-Mart effect - it used to be you
called a plating house and asked to speak to their
chemist, and the response was "which one?". Now they
are all having to compete on price with crappy third
world cheap plating that lasts a week , and they go
"chemist??? we can't afford a chemist anymore".
--- Ron Soave <soavero@yahoo.com> wrote:
> OK, with our diverse backgrounds on the list....does
> anyone on the list have a really, really good chrome
> plating house they use? Preferably someone who is
> NADCAP, and can plate chrome on aluminum (yes, you
> read that correctly) with minimal underlayment.
>
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