J2R casting machine

I’ve been operating my Neutec J2R casting machine for three
years now. It sure has made life easier for me. I have a question
for other owners. The instructions say to leave the inert gas
flowing (I use Nitrogen) after all casting is complete and until
the temperature has cooled to about 600 F.(which can take a few
hours and drain much or the tank) I fail to see the logic here.
Can anyone tell me why this is advised? It’s a major effort for
me to change tanks (distance and expense) and I have been
shutting it down after casting. I have also , on rare occasions ,
cast without the inert gas (cause I ran out) …no noticeable
difference. I haven’t contacted the company …thought I might
get a better selection of answers here. Thanks Darryl MacLeod of
Nova Scotia

Darryl, The reason that you keep the gas flowing is to prevent
the carbon crucible from oxidizing and prematurely wearing out.
What I do is turn the gas down to 2 liters/min and leave it on
for 20-30 min. Most of the glow is gone from the crucible at that
point so I think most (not all) of the oxidation that would have
taken place has been prevented. Seems to work, as my crucible
life seems to be pretty good.

Brett
Freedom Design and Contracting