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low temperature annealing oven

I would like to solution anneal aluminum to the W condition. This requires bringing it up to just under 1000 degF for an hour and then quenching in water. The parts I have in mind are slightly curved and about 50" long (after forming they join together to make a big ring) so the oven has to be pretty long and skinny.

Most of the posts I've seen here dealt with small ovens made from firebrick.. Any ideas for either making my own or finding something cheap out there? I'm kind of leaning towards gas fired since I've heard horror stories about firing up a 240V furnace and causing a power spike in my neighborhood grid that makes the power company pretty upset.

Thanks.

Joe

Reply to
joe_d_builder
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I'd probably take some 8" black stovepipe, make some appropriate cuts to get the bend you need. Bury the whole thing in a suitable box filled with vermiculite. (Of course I have about 4 bags of salvaged vermiculite that is headed for the dumpster but..) You might use a propane weed burner head but I think I'd find a couple of 240 volt oven elements, lay them in the bottom. If you strighten them out they are about 4' long, just about right plus they should take the heat ok.

As for the power cost, IIRC one of the elements runs about 3 kw, 2 would be 6 kw. You should be able to do your 1 hour hold in 1-1/2 hours or so,

9kwh total, $.60 at midwest rates, double that > I would like to solution anneal aluminum to the W condition. This
Reply to
RoyJ

Joe - see my posting of 2/4/06 on homemade electric oven with heat source

1500 watt 230 volt domestic stove top element. Dave Anderson
Reply to
David Anderson

I'm leaning towards a propane powered oven (for a variety of reasons). The question I have... how do I set up a PID to regulate the flow of the propane? Will it be a simple solenoid operated shutoff valve (that fluctuates on-off) or something that is linearly controlled (regulates the flow of the propane)? Are these difficult to set up?

Thanks.

Joe

Reply to
joe_d_builder

Oh, now I have a few other questions...

  1. What type of *flexible* insulation is good for 1000 deg F? I'm thinking a round oven will be the easiest to make and I can just wrap it with flexible insulation. I don't really want to go for the high temp (1800 deg) ceramic wool type if I can help it (expensive).

  1. I want to circulate air and will probalby use a blower that recirculates from end to end in the tube. What type of blower is good for this temperature?

  2. To keep the LPG burning "cleanly" how much air am I going to have to allow in (and vent out) as this unit operates?

This is a touch more complicated than first glance but it's sort of a fun problem.

Joe

Reply to
joe_d_builder

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