Need a non-conductor that is stable at high temp
Need a non-conductor that is stable at high temp
(OP)
I have got a small automatic MIG welding machine that is to be used in the field with a stick-out of 30 mm.
Problem is, from the moment everything is powered on (using a mobile generator), there is a certain arc voltage. The manufacturer gave a very useful gauge which can be used for several things, however as it is made out of Aluminum you cannot easily check the stick-out as it sparks heavily the moment you touch the torch (and the workpiece of course).
I want to have something small, handy, non-breakable (or relatively sturdy), and not electrically conducting that can handle temperatures of about 500 °C (930 Fahrenheit). Preferably easy to machine, and low-cost or good availibility.
I was thinking about bakelite, however I do not have any experience in plastics. Maybe there are better alternatives?
Other things that have crossed my mind:
Rock: ideal however cannot be shaped to form
Ceramics: too brittle.
Wood: probably my best bet so far. No problem if it won't last long as it's cheap and easy to acquire. Tolerance = +/- 1 mm, so when charred => bin and replace.
Thanks in advance for your input...
Problem is, from the moment everything is powered on (using a mobile generator), there is a certain arc voltage. The manufacturer gave a very useful gauge which can be used for several things, however as it is made out of Aluminum you cannot easily check the stick-out as it sparks heavily the moment you touch the torch (and the workpiece of course).
I want to have something small, handy, non-breakable (or relatively sturdy), and not electrically conducting that can handle temperatures of about 500 °C (930 Fahrenheit). Preferably easy to machine, and low-cost or good availibility.
I was thinking about bakelite, however I do not have any experience in plastics. Maybe there are better alternatives?
Other things that have crossed my mind:
Rock: ideal however cannot be shaped to form
Ceramics: too brittle.
Wood: probably my best bet so far. No problem if it won't last long as it's cheap and easy to acquire. Tolerance = +/- 1 mm, so when charred => bin and replace.
Thanks in advance for your input...





RE: Need a non-conductor that is stable at high temp
I think your thermal range is too high for generally available thermal resistant plastics.
If you can use wood, then you might consider getting refractory brick and slicing it into layers for disposable use. Yes, it is brittle, but could be used a few times before throwing away.
RE: Need a non-conductor that is stable at high temp
If wood had a hope, Teflon probably will too. It WILL NOT withstand continuous exposure to 500 C, but intermittent exposure it may take. It's a poor conductor of both heat AND electricity, and doesn't char.
Barring that, some kind of ceramic fibre millboard or even cellulose fibre-reinforced concrete (i.e. Hardiboard) would do the trick. Readily machinable? Not really, but you can bludgeon either of these materials into reasonably decent shapes if you don't mind dulling your tooling or using abrasives and taking care to manage the dust.
RE: Need a non-conductor that is stable at high temp
Hadn't really thought about brick or concrete, but if it works fine, I have no problem using that.
Moltenmetal: It does not need to be exposed for long time, only intermittantly and for a short time, indeed.
I am not a enthousiast of the brick idea, as the dust may get on the base material. Wood may have the same problem. No compressor on site, only a hammer and a wire brush.
I will see if I can get some teflon to test.
Will bakelite hold against these temperatures?
RE: Need a non-conductor that is stable at high temp
Bakelite is probably not going to survive your temperature requirement, and Bakelite is probably one of the more brittle plastics that you could have possibly chosen.
TTFN
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RE: Need a non-conductor that is stable at high temp
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RE: Need a non-conductor that is stable at high temp
Please stay away from the beryllia ceramic option. A piece of that material rattling around in a toolbox will generate respirable dust and if inhaled can result in a serious lung condition in susceptible people.
Bruce
www.accuratus.com
RE: Need a non-conductor that is stable at high temp
Warning! Teflon (PTFE) degradation compounds contain fluorine and other nasties like HF - not nice if you like your bones or corneas...
If you need to try polymers, try PEEK (with glass reinforcement)
H
www.tynevalleyplastics.co.uk
RE: Need a non-conductor that is stable at high temp
Bruce
www.accuratus.com
RE: Need a non-conductor that is stable at high temp
RE: Need a non-conductor that is stable at high temp
RE: Need a non-conductor that is stable at high temp
An old tig torch ceramic cup may be what you need.
B.E.
RE: Need a non-conductor that is stable at high temp
Mike Halloran
Pembroke Pines, FL, USA
RE: Need a non-conductor that is stable at high temp
Regards,
Mike