3D printing of teflon, PEEK, etc

Hi,

I am finishing my first reprap and have been reading widely on both repraps and commercial printers, mostly FDM method rather than powder-based methods.

I am of course going to print with ABS plastic, but eventually interested in developing a system to print teflon or PEEK or other high-vacuum-compatible polymers, in order to make parts to go inside a vacuum evaporation system. I have been unable to find if these thermoplastics can be extruded, but I don't see why not. Does anyone know?

Teflon seems like a really commercially important thing to be able to print, so since I can't find anyone that is printing it I assume that means there are problems with extruding teflon (or PEEK or others). Any ideas what these problems might be?

Thanks,

David

Teflon seems like a really commercially important thing to be able to print, so since I can't find anyone that is printing it I assume that means there are problems with extruding teflon (or PEEK or others). Any ideas what these problems might be?

Quote

According to DuPont, its melting point is 327 °C (621 °F), but its properties degrade above 260 °C (500 °F)
...
The pyrolysis of PTFE is detectable at 200 °C (392 °F), and it evolves several fluorocarbon gases[10][11] and a sublimate. Animal studies indicate that it is unlikely that these products would be generated in amounts significant to health at temperatures below 250 °C (482 °F),[12] although birds are proven to be much more sensitive to these decomposition products.[11][13]

While PTFE is stable and nontoxic, it begins to deteriorate after the temperature of cookware reaches about 260 °C (500 °F), and decomposes above 350 °C (662 °F).[14] These degradation byproducts can be lethal to birds, and can cause flu-like symptoms in humans.[14]
.

-http://en.wikipedia.org/wiki/Teflon

Sounds like it's going to be off-gassing quite nastily before it gets soft enough to extrude.
http://yarchive.net/electr/teflon.html
As per
http://cr4.globalspec.com/thread/33371/Welding-PTFE-to-PFA
you'll probably want to pipe the fumes out a window.

Also, you'll probably want to try a hot end with no ptfe/peek parts, like:
http://reprap.org/wiki/Arcol.hu_Hot-End_Version_3.0
perhaps. I'd also worry about the plastic parts of your extruder melting since you may be running your hot end higher than normal. You may also have trouble with your splines not gripping the teflon, but some (if not all?) of our stuff works with hdpe, which is quite slippery, so ???

It sounds like a fun research topic. Good luck. Let us know how it's going in reprap-dev, eh? Since you're a dev.

---

-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

The plastics that Stratasys can print via FDM are:
ABS
ABSi (higher impact strength variety)
ABS-M30 (higher strength and toughness variety)
ABS-M30i (high strength medical and food-grade)
Polycarbonate
PC-ISO (polycarbonate variety)
PC/ABS
ULTEM (Polyetherimide similar to PEEK)
PPSF (Polyphenylsulphone)

I don't know if any of these are vacuum-rated. Perhaps ULTEM?

I believe that the borosilicate glass nozzles I have been experimenting with can handle 325C or even higher. But that does nothing to stop the decomposition and out gassing. Possibly a sealed cabinet with something to catch or detoxify the gasses.

Mike

@jbayless: Thanks, that's a list I was looking for! Yes, ULTEM seems the most likely out of that list since it's similar to PEEK, but I am still investigating its outgassing properties.

@SB: Thanks for the links. Yes it may be some months before I start actually trying things (I've got to get ABS working first!) but will let you and other devs know if/when it works. It seems like teflon would not be the best bet any more, but there are other vacuum-compatible polymers

@rocket: I think a cabinet is a must. I might be able to find some large chamber from an old highvac system or something that I could put the reprap in to at least contain the gases and pipe them to the outside world... where they will just kill squirrels or something but not me

As standard plexiglass or MDF cabinet would be fine if there was a fan providing negative pressure. I was wondering if it would help to have a furnace section that burned the dangerous gases, or possibly a used catalytic converter from the exhaust pipe of a car plus some propane or something to help keep the temperature inside high. Or maybe just activated charcoal from a fish tank filter to soak the dangerous gases.

Mikie

rocket_scientist Wrote:
-------------------------------------------------------
> Or maybe just activated charcoal from a fish
> tank filter to soak the dangerous gases.


I really like this idea.

Should help with the smell from over heated ABS, too!

Does anyone have experience printing with PVDF? It is similar to PTFE but it has a melting temp of 177 deg C. I want to use it for its good chemical resistance.

Hi,
I'm looking into printing with Fluoroelastomers as well. You are getting something wrong though:
Teflon is a brand name and is use for quite a lot of chemically different polymers.
One of those is PTFE which can not me molten before it starts decomposing.
Because of this people have invented quite a few other chemically as resistant polymers that can be processed when they're molten (e.g. PFA, PVDF, ...)

If someone is using that stuff or plans to - please let me know.

lg Phil

I think the main obstacle is that plastics like these are usually not available as a filament in small quantities, so it's hard to do experimentation. If you can find a company that will supply filaments of such plastics, then I'm sure there would be many volunteers with RepRap machines willing to test them out and report back on their experience. =)

Otherwise, we might just be waiting for granule extruders to come online - although the design of a granule extruder might be very particular to the plastic's properties, so it might not be so easy.

Hello community!

There are always some projects going on with the devolopment of a granule extruder, beceasue of chaos properties of open source development, I will post this to notify you about the most recent (first quarter 2012) projects regarding granule extruders, including mine

I would like to notify you about my project, which is partially bases on research such as this forum topic and other simultanious projects:

My PROJECT PAGE
My FORUM TOPIC to give feedback after examining the project page obove

similar simultaniuos projects:
Marcus grinder/shredder+filament maker project
extruder printer head Project page
extruder printer head Topic page
Filabot project
you can also see my project page to see all the links and projects I've found on my research. It can save you time to follow my notes.

Greetings Ward

PTFE can not be melted it has no liquidous,

PEEK needs some stout ocmponents, it is a fluropolymer and will destroy anything but a few specfic super alloys.

....snip
>contain the gases and pipe
> them to the outside world... where they will just
> kill squirrels or something but not me

I think this idea sucks.
F Squirrel
PS Argh, kof

3D printing, and varment controle all at the same time...now how cool is that! ;-)

Short of the fact that is seems that PTFE is a one way plastic, that is to say that once it is formed it cannot be effectively recycled in any way, just how would one plan to get it to stick to the build bed???

I have considered printing both PEEK and FEP (Which is a fluoropolymer like PTFE, but can be conventionally melt processed as a thermoplastic)

My stumbling block in both respects is acquiring filament. I am going to invest in a filastruder or similar at some point once they are a little more prove - or make my own. Resin pellets are much more available than filament.

As far as I know neither are particularly harmful to the processing equipment.

I would be using my E3D-v4 All metal extruder, which has 316 Stainless and brass in contact with the molten plastic. You can see more details on the extruder in the link in my signature.

To get FEP to stick I would probably go for a mechanical route, using an over-extruded raft on something like perfboard, so plastic flows through the holes, die swell causes it to mushroom slightly on the the other side of the hole locking the raft to the bed. Then printing on the raft continues as normal.

Thoughts on these approaches?

I am deadly serious when I say I want to print a working J-Head type hotend out in full, using dual extrusion of FEP and PEEK, but obviously with a brass nozzle.

---

I Design/Sell all-metal hotends. My company is called e3d-online - you can buy at [www.e3d-online.com]

Quote
SanjayM
I am deadly serious when I say I want to print a working J-Head type hotend out in full, using dual extrusion of FEP and PEEK, but obviously with a brass nozzle.

Why obviously a brass nozzle? You could print a mandrel out of carbomorph and electroform the metal part of the hot end around it.

the hot end ive been helping brad research would be capable of printing at upwards of 600c, with no jamming. having a ventilator would be a must though.

Has anybody had any experience with printing MEA's for fuelcells , i understand the main component is a specialy forged flouroplastic membrane, around two flat electrodes.
I realise the effiency would be way down, because of the lack precision in the construction, but the reduction in cost would be significant. Currently a 2cmx2cm MEA costs about $100.

We have been working on this for some time and we have FEP now available here
We hope to introduce PEEK later this year. Full-metal hotends like E3D's are required.

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plastic2print.com - Performance Plastics for 3D Printing

Hey, I work for a plastics extruding company that deals with PTFE a great deal, and depending on what exactly you are making, you may want to consider using ECTFE if possible. If you can find a supplier ECTFE is similar in price to the other flouropolymers, with a lower melt temperature and mechanical and chemical properties approaching that of FEP or PTFE. Not sure if there is a history of using ECFTE in 3d printing though.

Basic info:
[www.zeusinc.com]

Chemical Resistance chart:
[www.zeusinc.com]

Density (g/cm3): 1.7 | Surface Hardness: RR93 | Tensile Strength (MPa): 30 | Flexural Modulus (GPa): 1.7 | Notched Izod (kJ/m):1.06+ | Linear Expansion (/°C x 10-5): 20 | Elongation at Break (%): 200

Strain at Yield (%): 5 | Max. Operating Temp. (°C): 130 | |Water Absorption (%): 0.01 | Oxygen Index (%): 60 | Flammability UL94: V0 | Volume Resistivity (log ohm.cm): 15 | Dielectric Strength (MV/m): 40

Dissipation Factor 1kHz: 0.002 | Dielectric Constant 1kHz: 2.6 | HDT @ 0.45 MPa (°C): 115 | HDT @ 1.80 MPa (°C): 76 | Melting Temp. Range (°C): 270 - 300

Edited 3 time(s). Last edit at 11/12/2014 10:34AM by relytyarg.