Carbon filament for electrical mold heating
Carbon filament for electrical mold heating
(OP)
Hi All,
Just wondering, has anyone tried heating of molds by wiring carbon filaments that are already laid into the mold as structural reinforcements of the mold. If so, what are the gotcha's? What are parameters that one would need? Would this save energy and give me a Greener part
?
Would really love some discussion on this.
Thx,
N
Just wondering, has anyone tried heating of molds by wiring carbon filaments that are already laid into the mold as structural reinforcements of the mold. If so, what are the gotcha's? What are parameters that one would need? Would this save energy and give me a Greener part
Would really love some discussion on this.
Thx,
N





RE: Carbon filament for electrical mold heating
The first fundamental problem is that composite molds are poor conductors of heat so temperature uniformity is poor if you use a constant power heat source like resistance heaters rather than a constant temperature heat source like an air circulating oven.
Then there are electrical safety issues. You have to control the current path and insulate so that people can't get hurt. Carbon is not a great electrical conductor so voltages can be high.
If you look at standard electric cartridge heaters the resistance wire may be at 1000F or 1500F when the surface of the cartridge is 500F which heats an aluminum mold at 300F. Carbon will oxidize in air above 600F. Epoxy resins cannot be exposed to more than 400F for long without degrading.
In vacuum furnaces carbon-carbon heating elements have been used for some time and will operate up to 3000F.
RE: Carbon filament for electrical mold heating
So if I understand correctly, its better to soak the entire mold in hot circulating air, w.r.t. even heating locally? How about flat heating elements with aluminum sheets on them, attached on the mold (conforming to the mold)?
I would like to do away with recirculating hot air heating. But from what you seem to experience its the way to go for uniform heating. Am I reading you correctly?
RE: Carbon filament for electrical mold heating
RE: Carbon filament for electrical mold heating
You can increase thermal and electrical conductivity of your laminate by adding carbon black particles or better carbon nanotubes. This will help on evenly heating the mold.
RE: Carbon filament for electrical mold heating
RE: Carbon filament for electrical mold heating
I though it would be a great way to heat a mold without heating the whole shop.
I went back to using heat tents, after finding under cured areas in my parts away from the carbon filaments.
B.E.
RE: Carbon filament for electrical mold heating
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Not sure how well the .pdf covers electrical heating (if it does), but that's the stuff.