DIY Filament Review for PEEK (Polyether ether ketone)
Source of pellets: [
www.filastruder.com] … al-pellets
Note, I emailed elmoret(Tim) and he was able to order these pellets very quickly(<1 week). Thank you Tim!
Pre Drying instructions: I used a toaster oven at 150C for 4 hours -see figure 1. Not sure if this was overkill, but it worked and the filament was dry enough to print with. After the pellets were dried I let them cool down, put them in a ziploc back, and loaded them into my hopper 3 days later.
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Figure 1: Pellets in oven
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Figure 2: Pellets in bag
Filament extrusion setup: Filastruder with frankenstein Filawinder built from scraps in my shop - see figure 3
Note, the Filastruder has been modified to have 18v supplied to the heater and 12v to the motor. This allows me to reach 350C+ extrusion temperatures. I also added glass fiber insulation to the end of the thermocouple as the the PTFE insulation is not rated past around 200C
I also built airtight silicone sealed hopper and attached that hopper via drilled and tapped M3 holes on the barrel of the Filastruder.
The plastic box around the Filawinder was an attempt to make it easy to seal off spooled material from the outside humidity.
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Figure 3: Filastruder and frankenstein filawinder mounted on plywood
Extruder settings:
Extrusion temp 345C
Extrusion rate: 13in/min - This is about 1kg per 2.5hrs I think.
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Figure 4: PEEK filament
Machine used:
Custom Big Fused Filament Fabrication 3D printer, CoreXY with 21.5x12x18in build volume, heated bed, heated chamber, flexible thermal barriers, E3D Titan Aqua, E3D super volcano, E3D .6mm copper plated super volcano nozzle, PT100 temp sensor, Duet Wifi, Nema 23s, Ball screw for Z, removable spring steel build plate held on by high temp magnets, PEI build surface.
Machine settings:
Print temp 370C Nozzle, 150 bed, 70C chamber
20mm/s 100% infill, 2 walls
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Figure 5: Custom BFP (Big FFF 3D printer) printing a PEEK double helical gear
DIY PEEK Filament Tolerances: 1.62+/- .8mm NOTE: I am still working on getting the tolerances right, but I am confident I can get it to +/- .1mm. My filawinder setup is hacked together incorrectly and needs to be rebuilt to get better tolerances. I will post an update when this is completed.
Printed part: I opted to go with a very small test print so I wouldn’t have to worry about warping. The test part is a scaled down version of a Filawinder drive gear. The top part of the print had very poor layer bonding and confirms that in order to properly print PEEK you need to have the ambient air temp around 130-140C. Having the ambient air temp near the glass transition temp of the plastic helps with layer bonding. This is why large ABS parts from Stratasys printers never have layer separation mid part. Since my chamber temp was around 75C the layers cooled down too quickly and were not “sticky” enough to bond to the next layer. Also a word of warning, the part stuck too well to the PEI build plate - see figure 7. In the future I will be using a piece of steel with PVA glue on it and seeing what happens. I will post an update when I print with different chamber/ bed temps.
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Figure 6: Printed PEEK double helical gear
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Figure 7: Poor layer adhesion
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Figure 8: PEEK part sticking too well to PEI build surface
An interesting note:
Something that I found fascinating was that when the filament was extruded it came out semi clear brown and then as it cooled it hardened into light milky brown - see figure 8. This occurred both on the printer and Filastruder. It was more clear when extruded on the printer. This may be due to the higher extrusion temp (370C vs 345C).
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Figure 8: Filament color and opacity change, clear brown filament section is circled in blue
In conclusion:
My initial testing is very promising. With some more testing and higher chamber temperatures I believe I will be able to start making larger PEEK parts with strong layer bonding in no time. As it stands now I need to fix my winder system to get better tolerances, but there is no reason that I see beyond my winder issues that would make it hard to get +/- .05mm tolerances. I will be updating this thread as I get closer to establishing a proper workflow for PEEK. Thanks for reading! If you have any questions or feedback feel free to post below or PM me.