Out of 1,700 netters, someone should have an idea about this:
We need expertise advice immediately to solve a mystery with clogging
high speed automatic dispensers. Three silver epoxy pastes give same
clogging. Fresh pastes are bought. Same. Dispenser screws, tubes, pumps,
all details are cleaned thoroughly. Same. New dispenser parts installed.
Same. Whatever we do. Same. After running some minutes-hours: clogging
in the needle. Some say that the room humidity must be very exact in
order to make the dispenser epedize well. Others talk about local curing
inside the paste. And some think sedimentation can be the plague.
Experts from the paste manufacturer will be here in one or two days, but
according to my experience, they seldom have that kind of knowhow,
machine makers can have, this one not. Most oftenly, the knowhowers are
people like you, dear nett(l)ers.
I have my own theory, but can't prove it yet. Namely, that this
"conglomerate" or mix of fluids and silver flaws (1-50um) can be
PRESSURE DEPENDENT, i.e. at certain constant or momentary pressure,
there will be a separation in the narrowest part, the needle, fluids
will drop out and separate, leaving the coarser silver flaws without
fluency, they will clog. Also, I have seen that the inside of the needle
(inner dia 100um) is not polished, but has a rather grainy stucture,
likwise the rotating helix that feeds paste. Both should be polished, I
suppose. There is a science that use morphology and fluiding dynamics
that possibly can give a clue, but I'm rather far from that art, maybe
some of you have education of the sort.
Familiar to someone?
Remo@Alenia, if you read this, please contact me, I have lost your
adress.
Thanks in advance/
Ingemar Hernefjord
Ericsson Microwaves Systems
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