I have supported my production departments with respect to the wavesolder
machines at various companies for the last 20 years and have always
advocated keeping the solder molten as opposed to allowing it to cool down.

The equipment usually has the timers and ability to idle the solder pot
temp down to 425 F from 500 F when there is an extended period of non-use
upcoming, and it automatically brings the temp up again before it is needed.

As far as the fires are concerned, I thankfully do not have any experience
in that arena, and I like to think that this is because we keep our machine
immaculate.

Immaculate means that besides the daily, weekly, and monthly cleaning
normally performed, we also dump out all the solder at least once every two
years and completely clean the solder pot wall, etc.

I still have three machines and the oldest one has as good if not better
yields as the newer ones.

BTW,  I have observed that my absolute best yields are always right after
this maintenance and gradually trail off to the normal yields after about
two months or so which I attribute to the solders ability to demonstrate
uninhibited flow along the wall surfaces as well as its lack of
contamination.  Both degrade with time.

Phil
-------
At 02:17 PM 6/11/99 -0400, Scott Mcanall wrote:
>There is also the savings to maintenance of the solder pots as the majority
>of solder pot life is used up in the heating up of the solder pot.  the
>starting up phase stresses the heaters and the solder pot tank.
>
>Solder pot controls systems need to have either, proper watt density/solder
>mass ratio or redundant non-thermocouple backup, to insure the safety of an
>unattended pot.  Simply fusing the pot to match wattage is a not insurance
>against the pot running away.
>
>The most important thing about the fire safety of solder pots and electrical
>machines in general is MAINTENANCE, MAINTENANCE, MAINTENANCE.  The
>electrically caused fires that I have been involved with all had 1 thing in
>common.  The pots were allowed to become filthy with flux solids, paper and
>scrape parts.  When this pyramid of filth had piled up to the lip of the
>solder pot, all it took was a spark from a heater going down and POOF...
>solder pot fire.
>
>We at RPS have been making solder pots for 12 years,   our standard
>reccomnedation is to leave the pots on all the time except long holidays (4
>days or more).
>
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