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NEON- Sintering/Oven talk
Listers-
Ed Dezuzio and I (Tom U.) have been carrying on a conversation about
sintering and baking units that arose from the discussion of the units that
went funky on the electronic transformers. I think some of the posts have
ended up on the list and others not. I appologize if this has happened.
To try and clear it up, I've taken some of the last several posts between
us and combined them into this one. Tom U.
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Tom U. wrote:
> Ed wrote:
> >The sintering process I was refering to is just that. Baking the
>coated glass to bind the coating to the wall of the glass tube and
>remove any trace of the binder itself. I am pretty sure that if the
>glass is not outgassed in the oven it will take the bombarding
>procedure as oppurtunity to further outgas and/or sinter. Tom Wrote Back:
>I imagine after oven baking, it's unlikely that further outgassing or
>sintering needs to take place, right? They sure pump "clean."
Ed is replying:
Yes they do pump clean but if not baked through out there will indeed be
more outgassing from remaining binder. Remeber the definition for Sinter
is something like "to make two components one by means of heat." The
binder is a needed component for this but must not remain in the tube.
If you recall my initial reply was in regards to overall tube staining
and or darkening. If a precoated tube is not baked through out prior to
us bending it this would have the same results as a post coated tube not
being baked through out prio to bombing...eletricly.(Is that a word?)
SNIP
ED WROTE:
> >Once the tube is baked the only other potential moisture and
>>contaminents come from attaching the electrodes and condensation.
>>Compared to the moisture from bending these are minimal.SNIP
TOM ASKS:
SNIP
>Could "standard" electrodes hold up to this, though, if you wanted to
>do it after or doesn't that make any sense? Is the only way to do bake
>post-electroding to have an oven pumping system? I'm wondering this as
>I saw the shop that does the oven pumping doing it, obviously w/ the
>'trodes on and I'm wondering if completed units could be baked, then
>electrocuted, er, bombarded.SNIP
I have tried that as well..First trode then bake..next day bomb. Really
no great advantage and I always qestioned the sanity of the boss on this
one. Why bake out contaminents with only one porthole of escape,which
would be the tubulation. Why give those contaminents a place the re-
absorb themselves, especially at the tubulation. What my objective is is
to bomb similar to Ted's practices. If I recall Ted pre-bombed his glass
to 100* pulled vac and then backfilled and bombed for real....Maybe that
was a dream...Hmm...Either way, the same principle but just a little
more intense. Then of course you have to explain why your bombing costs
are up 30%.
Peace.
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***************
Ed is replying:
>If you recall my initial reply was in regards to overall tube staining
>and or darkening. If a precoated tube is not baked through out prior to
>us bending it, this would have the same results as a post coated tube not
>being baked through out prio to bombing...eletricly.(Is that a word?)
So, getting back to one of my initial questions. Is there a way for us to
tell when a factory coated tube hasn't been baked thorougly enough and we
are going to have troubles because of that?
>I have tried that as well..First trode then bake..next day bomb. Really
>no great advantage and I always qestioned the sanity of the boss on this
>one. Why bake out contaminents with only one porthole of escape,which
>would be the tubulation. Why give those contaminents a place the re-
>absorb themselves, especially at the tubulation. What my objective is is
>to bomb similar to Ted's practices. If I recall Ted pre-bombed his glass
>to 100* pulled vac and then backfilled and bombed for real....Maybe that
>was a dream...Hmm...Either way, the same principle but just a little
>more intense. Then of course you have to explain why your bombing costs
>are up 30%.
>Peace.
Doh! Uh, yeah, that does make sense. If the 'trodes are on, the only
escape is through the tubulation. Not too efficient unless oven pumping.
Do you think you'd need a 30% cost increase to make it feasible?
Tom U.
***************
***************
>So, getting back to one of my initial questions. Is there a way for us to
>tell when a factory coated tube hasn't been baked thorougly enough and we
>are going to have troubles because of that?
SNIP
>Doh! Uh, yeah, that does make sense. If the 'trodes are on, the only
>escape is through the tubulation. Not too efficient unless oven pumping.
>Do you think you'd need a 30% cost increase to make it feasible?
SNIP
If the glass were baked out and the efficiency of that process were rated 1
to 10 you would notice extreme outgassing while bombing IMO at 7 on the
scale. Perhaps even during bending?
Yes I think 30% is a good round number for that. I do repair HG tubes
already and the cost for that is
16% higher than a NE repair. It is all labor. The additional floor space
for a drying table and oven along with electricity costs would easily pick
up the additional points.
Peace, Brother of the Torch.