Very hot heating element wire lead connections

[corrado33]

Hi all,
I need some ideas. I have a furnace that gets up to 1000 C and I need to attach leads to parts of it. The connections will also get up to around 1000 C so I can't simply solder it. I have been using completely physical connections but after a while those break off. My NiCr wire is getting shorter and shorter so I need a more permanent connection. (It's actually Kanthal wire, but the same principle.)

Tomorrow I'll have access to a spot welder, so I will try that. However today I think I'm going to experiment with melting the wires together. I have some extra wire that I can use as practice. Basically I was going to attach some leads a cm or so apart on two separate pieces. Physically hold the wires together somehow, then pass a crap ton of current through it. (10A maybe?) I don't have any power supplies that'll go above 12A unfortunately. Well, none at work (home is a different story, but that's in my house, which I'd like to not burn down.)

Any other ideas? Do you think melting them together will work? Do you think I'll be able to melt them?

I could always use a couple of car batteries if my power supplies can't provide enough power... I mean, that short of a piece of wire is essentially a short circuit, so I should have no trouble getting many many amps to flow through it.

Yes, I realize this sounds like a terrible idea. But at this point I have few other choices. The first choice is the spot welder tomorrow though. This melting idea is only a backup plan.

[Tomorokoshi]

Do you have a picture of the area where those connections would be made?

Perhaps look into the methods used for welding the tips of thermocouple wire together.

[T3sl4co1l]

AFAIK, crimping is used for those.

Take the wires out of the hot zone, and use much heavier metal (thicker = less heat dissipation, more thermal conductivity) to make the joint.  Thermal cycling and oxidation are the problem, even if it's all refractory metals.

Also mind that Kanthal is brittle after use, IIRC, so you might not be able to service it...

Tim

[Shadetreeprops]

Hi all,
I need some ideas. I have a furnace that gets up to 1000 C and I need to attach leads to parts of it. The connections will also get up to around 1000 C so I can't simply solder it. I have been using completely physical connections but after a while those break off. My NiCr wire is getting shorter and shorter so I need a more permanent connection. (It's actually Kanthal wire, but the same principle.)

Tomorrow I'll have access to a spot welder, so I will try that. However today I think I'm going to experiment with melting the wires together. I have some extra wire that I can use as practice. Basically I was going to attach some leads a cm or so apart on two separate pieces. Physically hold the wires together somehow, then pass a crap ton of current through it. (10A maybe?) I don't have any power supplies that'll go above 12A unfortunately. Well, none at work (home is a different story, but that's in my house, which I'd like to not burn down.)

Any other ideas? Do you think melting them together will work? Do you think I'll be able to melt them?

I could always use a couple of car batteries if my power supplies can't provide enough power... I mean, that short of a piece of wire is essentially a short circuit, so I should have no trouble getting many many amps to flow through it.

Yes, I realize this sounds like a terrible idea. But at this point I have few other choices. The first choice is the spot welder tomorrow though. This melting idea is only a backup plan.

First use large physical connections to extend your wires back out, cover with heat shrink, Then purchase REFRACTORY LINING..and insulate the wires with it. wrap with metal tape, and put a metal mesh insulator around it. then pad the area where the heat comes from with more REFACTION insulation. This stuff can withstand these temps, and should then stop the damage to the wires.

just like in really high end Arch welders, you can sometimes find it with the refraction lining in them. or like my digital smelting furnace, they have to protect the wires with that stuff from the heat..melts everything up to platinum like nothing.