Ceramic hotend...?
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Hi,
i have see a "ceramic hotend".... seems interesting.
Can someone give feedback about this kind of hotend?
Thanks
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Do you have a link? What is made with ceramic? The heater? The nozzle?
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I'd imagine it'd be not very good due to ceramics being insulators
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Mmm...
Maybe Last more time to reach temp.... But when reach.... Ceramic hold well tempemrature as stony stony material...
Think remember, The furnaces of the foundries have a ceramic coating
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If you're looking for exotic nozzle materials, the Olsson Ruby could be a good start before trying out ceramics.
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I'm using this exact product¹! It works well, but there is a lack of inertia, and temperature drops when you extrude fast (when purging, for example). But I do recommend it, it is very nice to have a compact hotend. It allowed me to have small tubes to blow air at the output of the nozzle:
https://www.logre.eu/wiki/Tête_à_FNU#Ventilation_de_la_pi.C3.A8ce
Note that I use a FNU (http://www.1730hotend.com/filament-nozzle-units/brass/1-75-mm.html) which will soon be replaced by the Zatsit version, which only has a threaded rod, allowing easy change of nozzle.
¹: I think this is also the one we can see on the Zatsit printer examples (https://www.kickstarter.com/projects/396334038/zatsit-the-awesome-delta-robot-and-3dprinter-with)
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The ceramic ring is the heater, so i guess the time to reach the temp is at least the same or maybe even shorter.
Way less mass to heat. -
Furnaces use ceramics so they don't lose heat to the environment. With a hotend you want a high thermal conductivity to keep the tip temperature accurate. Hence why the blocks are usually aluminium or copper.
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Correction: I only use the ceramic heater, not the nozzle... I may try it, though, as I have to order from them.
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Looking closer, their nozzle does not seem to be in ceramic!
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BTW, there is also this product, part of the all-in-one hotend: http://www.hotends.fr/fr/home/63-corps-de-chauffe-ae.html
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@gavatron3000 They solved this by putting the thermistor in the nozzle.
For me it is an interesting design, so I am thinking to buy one, when I will switch to 24V -
@obeliks see how you go I'm interested to see your results
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I will post results, but it will take some time. I am not planning the switch in near future.
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I looked into these some while back. What you see is an annular (hollow cylinder) heater around an aluminium block. The ceramic part is just the insulation. The heating element is just nichrome wire wrapped around a ceramic core. So in that respect, it's much like a conventional cartridge heater but annular in shape. Oh , and the two wires are for the heater - you still need a thermistor (at least I haven't seen one with integrated thermistor).
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@gavatron3000 said in Ceramic hotend...?:
I'd imagine it'd be not very good due to ceramics being insulators
Actually, there are some ceramics that are good thermal conductors. I know this because while I was doing my PhD I had to build some waveguide carbon dioxide lasers, and I needed a material that was a good thermal conductor and good electrical insulator. Beryllium oxide is one of the best, but highly toxic. Alumina is not as bad as you might think, it conducts heat about 30 times better than glass. For the lasers I settled on hexagonal boron nitride, which has a thermal conductivity about 600 times better than glass (more than aluminium) along the layers and 30 times better perpendicular to the layers.
My guess is that ceramic hot ends are made from either alumina or hexagonal boron nitride. Both are white. Alumina is hard, hexagonal boron nitride is soft like graphite.
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@obeliks said in Ceramic hotend...?:
@gavatron3000 They solved this by putting the thermistor in the nozzle.
I drilled my FNU to insert the thermistor as TriangleLabs does with there nozzle... That's maybe why I can see the temperature dropping when I extrude fast: when thermistor is in the heater block, you don't see fast variations.
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@fma That makes sense. Maybe that nozzle is a bit better since it is bigger than usual E3D
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Interesting! I had a general view on ceramics and didn't know that David. Ceramic wrapped heater I think would be good. I guess similar in a way to how e3d put a silicon sock onto the heater block.
Always good to keep an open mind