proper heating element connectors

[Enzy]

I have been having some issues with a heat tunnel I work on from time to time, whats happening is the elements have threadings on the ends and connectors are held to it by a nut or 2 but the because of constant heasting and cooling the nuts and connectors get worn easily.

the tunnel operates at about 700 degF, can anyone recommend me to some good connectors and even nuts to secure them, currently I am using some 8mm wires and the heat elements are 7000w.

 

[shaiko]

A picture of the "problem at hand" will be nice...

 

[Enzy]

I cant actually pull down the machine now as its working constantly 16 hours per day now, when it is down I can do so though. I can upload a pic of a heat element it doesnt matter the type though in my eyes.



uploaded is a pic of a heating element and where the threading is I use washers and nuts to hold the terminals I attach but the the nuts keep getting damaged quickly because they cant withstand the heat, I am asking if anyone knows any good heat resistant connectors and nuts to use in a heat tunnel.

 

[KlausST]

Hi,

Is the problem the max. temperature, or is it the temperature cycling?

I assume it's more the cycling. Then you need a spring that can compensate the thermal expansion.
Nut-connector-nut without spring is mechanically problematic and thus the construction may become loose.
..increased contact resistance, increased power dissipation, increased temperature...

For sure it needs to withstand the temperature

Klaus

 

[Enzy]

Ok I see, so look at the pic I sent just now, it has 2 small nuts and a white insulator it seems, your said I should use a spring so in other words I could make connections in this order:

white insulator, nut, washer, terminal connector, spring, washer, nut.

and that should give a good connection to terminals I see the logic in that but those terminals on the elements are about 3/16" in diameter do you think I can get springs that can withstand 300 plus degC for extended periods of time especially that size also what material best do you think could withstand the heat when using the nuts, stainless steel or some other regular metal nut.

 

[FvM]

The photo suggests that the heater is designed for use with liquids or may be steam generators with maximum 100 or 150° C at the brass feed-throughs, limited e.g. by the gasket temperature rating.

For usage at > 300°C, I would avoid connectors, use temperature resistant cables and screwed connections. Why would you place the connector in the hot zone? Review how connections in an electrical cooker are made.

 

[Enzy]

The machine is a ShrinkPAk 5000 its designed to wrap plastic around cases of water and melt the plastic to hold bottles firly together.

I guess I would have to get a picture the actual set up, where the connectors are will become really hot just the same even though they aren't exactly where the bottles pass, the element extends over to where the bottles are while a metal plate separates the connection portion, I am using temperature resistant cables but they still need to be terminated to the heat elements which have threaded portions to it like the example photo I sent so thats why I used a connector to terminate the wires into and a nut to hold it to the connectors.

 

[KlausST]

Hi,

nut, washer, terminal connector, spring, washer, nut

Basically yes.

Use wires with high temperature isolation. Silicone, or glass....
And use crimping technology or welding technology.
You need a proper crimping tool to get reliable gas-tight connection.

Klaus

 

[Enzy]

The terminals I attached are crimped, I don't have a crimping tool so it could be crimped a bit better. Now after crimping heat resistant wire to terminal I could Weld it to heating element terminals, is that what your saying?