Filament vs Pellet 3D Printing | Which is the Future?

Please help me to improve the Pellet Extruder by telling me your concerns and wishes through this link before I make it available to everyone ➡ greenboy3d.de/

As an injection molding designer and engineer I can contribute with some things: A) The screw starts with low inner Ø and then gradually increases its inner Ø. This is because the pellets form air bubbles that get traped in the screw if the Ø is constant. This gives inconsistent flowrates. B) You MUST heat the entire screw, from start to finish. Even the nozzle if you can. C) Most pellets are thought to be used in injection, extrution and blow mold. The relation between the size of the pellet and the screw of those machines is many times larger. However, this is not true to this case, where the Ø of the screw only lets 2-3 pellets to get in. Tips: Make screw wider, with progressive inner Ø. Let some gap in the fit so air can go away (about 0,2 mm). Heat the entire screw, from start to finish. You may use more than one heating element. PS: Your idea is brilliant, keep on that study case.

I think ill be switching to this. Filament is crazy expensive for just being plastic string. Thanks

In commercial extrusion, in between the barrel and the tool (your nozzle) you would have a pump that holds back pressure on the barrel and maintains a constant pressure in an expansion chamber. The expansion area will have its own heater and pressure and temperature sensors. These form a closed loop system with pressure and temperature sensors to control pump speed, screw speed and temperature in both zones. A well balanced arrangement of PID controllers keeps the right flow at the right temperature at the tool. For what it's worth, the pump seal is maintained with compressed air to keep material leakage and contamination down. One really cool aspect is that you can change what material you are loading the barrel with on the fly. Color can be adjusted in real time and composition can be changed with little or no waste.

things that could improve print consistency 1. dual heating zones first pre-heat second working heat (which means possibly longer hot end) 2. Sift your pellets to separate them by size then workout flow rates based on pellet size used

As someone who used to material handle at a plastic injection company. I knew there was something missing from 3d printing. I am looking forward to your next video.

Congratulations to a good start of your channel. Well deserved considering the way creativity translates to content.

If we use a 1.75mm nozzle with your extruder it would be very easy to make custom home made filament. Would you make a contraption that could make good quality filament with even thickness using your screw extruder setup? it doesn't need to be very fast. Most of us have basic filament 3d printers which we don't wanna tinker with so a cheap home assembled filament maker would actually be something I'd like to buy to go with my 3d printer.

Not that you asked for advice, but I dug through my old material processing notes to see if anything jumped out at me as far as consistent flow rate. It appears commercial extruders have 3 zones: feed, compression, and metering. The feed zone just moves pellets and begins to heat them. In the compression zone, melting increases, as does the minor diameter of the screw. Air is expelled backwards out the feed section. In the metering section, the minor diameter of the screw either increases slightly or is uniform, but not as much as the previous section. The polymer is 100% melted and pressure builds, which will eventually force the melt through the die (nozzle). The pitch of the screw threads has a complex relationship with flow, as (approximating polymer as a Newtonian fluid), forward flow is proportional to cos(angle)sin(angle), whereas backward flow (which is bad) is proportional to (sin(angle))^2. At the end of of the screw, having the interior of the barrel taper similar to the screw end is preferable to a 90 degree turn in the interior barrel wall. A tapered design should control flow and allow polymer coils to relax before being extruded. A longer "land" (distance between end of screw and nozzle, after the tapering of the barrel) will give coils more time to relax, but may increase pressure and slow flow rate.

Not an engineer, but have you tried a pellet screw that gets progressively tighter at the bottom? In my mind, it would make sense that the flow rate would be more averaged because pressure from threads above would be shoving the pellets down into the extrusion barrel. Excited to see your idea for recycling plastics in the future.

i hope you will get recognition, this pellet printing looks interesting and seems a better choise but the problem is availability, few or none companies who would like to invest into this technology, but so far 3D printing is changing, i hope that i will see it in a near future.

As someone with 13 years of experience in the field of extrusion, particularly adept at utilizing palets and screws, it's worth noting the significant transformation we've undergone. While our primary focus used to be filament production, the intricacies of screw adjustment have become paramount. When addressing screw depth and barrel fitment tolerance, we've observed a remarkable reduction in output variations—from potentially as high as 15% down to a mere 5%. This is achieved through meticulous adjustments, ensuring the screw depth and barrel fitment tolerances are finely tuned to operate in close proximity. Moreover, optimizing the preheating process for palets in the hopper has proven to be a game-changer. By initiating the heating process from the nozzle end at higher temperatures and gradually decreasing towards the back, we've effectively mitigated the risk of pallets becoming lodged within the screw mechanism. This careful calibration ensures a smooth and efficient extrusion process, minimizing downtime and maximizing productivity.

The future is in making your own filament at home, mix your own colors, reuse the same spool, ensure filament diameter without blindly trusting the manufacturer. The high cost is due to the middle man, also your comparison is based on pellets (ali) vs spools (us/eu vendor). If you look at the spool prices on ali it is already a lot less, if making filament at home becomes viable again or a community rises up like voron etc. with thousands of people putting their minds together I am sure they'll come up with something

This was a great watch and so well explained, to get bags of peelets and be able to print guilt free with such a low cost would be extremelly liberating. Pkease continue to evolve your pellet printing process and cant wait for the desktop 3d printer pellet conversion video...i have Bambu A1 Minis and Anycubic Kobra 2 Pro so hopeing these feature...fantastic work.

Here's an idea... Serialize two print heads: 1) The first is fed pellets which extrudes filament, which is cooled and has a buffer coiled area perhaps. 2) The second consumes #1's filament and now you're printing with all the abilities of FDM but you're producing your own filament from pellets.

Okay, you've got my sub, because I really want to see more about your pellet extruder. I really think this is the future of 3D printing, for all of the reasons you state. The clearest thing is that if recycling requires grinding into pellets anyway, the intermediate step of having spools of filament is just a big waste. One thing I noticed when you showed your screw removed from the barrel, is that it doesn't look like your pellets are getting fully melted until just before they get to the bottom of the screw. It seems to me that this would result in some of the air between the pellets doesn't have time to rise in the screw, and therefore it might be getting mixed into the melted plastic. This would result in both inconsistent flow and lower strength in the prints. I know my suggestion will not be welcome, and of course you've got a great deal more experience with this than me, but I think the screw just needs to be longer, or perhaps the heater needs to cover more of the barrel. Another thing comes to mind: I had a toy when I was young, back in the 1960s, that was a set of nylon molds and an injection molder for making toy soldiers and other things. The injection molder just had a vertical cylinder, about 20mm diameter, with a plastic plunger that fit in its top. The plunger was tapered at about 45 or 60 degrees, and there was a matching conical section at the bottom of the cylinder, with a small (2-3mm) hole in the bottom. Below the cylinder was a housing with a rectangular hole that you slid the mold into, and of course the mold had a hole in its top that lined up with the hole at the bottom of the cylinder. The molding system came with a few bags of pellets, which I am guessing was a mixture of paraffin and polypropylene, because it melted at a lower temperature (don't know what temperature, but low enough it was hard to burn yourself with, like maybe 90 degrees C, and it smelled like polypropylene or maybe polyethylene, but the resulting toy soldiers were softer than either of those. But my point is, the whole cylinder was the melt barrel, and you poured in as much of the pellets as would fit without being packed, and all of the molds were designed to use about the same amount of plastic, so filling up the cylinder left you with very little left over, AND you could cut that up with scissors or a knife to use on your next parts. And in fact, I cut up most of my parts to make other parts, because it was more fun making them than playing with the toy soldiers! So all of that to say, maybe a plunger is the better way to go, to get consistent flow and strong plastic. I realize the problem, that you can't make anything bigger than the barrel will hold, but there are ways around this as well. It's so great to see what you have accomplished, and i look forward to your future videos. Good day, and good printing!

Excellent work! Ultimately I think this approach will only be practical in high-volume printing situations, where perfect precision isn't required, but wow your print quality really is excellent given the variance in pellet sizes. I tell myself this is something I don't need (imagining the mess of spilling pellets like spilling a bottle ot glitter), but I'm so gawd damn cheap that I can't deny that buying kilos of raw pellets for dollars or having a path to recycling is extremely appealing to me. 😅

I agree with every advantage you cited from pellets printing, from price to flexibility of mixing colors, buying smaller quantities and using different materials. I think the main limitation of this method will be speed. Now we are going to 300mm/s printers (the core XY profusion). The pellet extruder seems way heavier than the filament ones, and it will limit speed. The pellets chaking form hi speeds may also be an issue.That said, I don't believe pellets will be mainstream in FDM 3Dprinting, but I do think there will be a solid share for it if it gets sufficiently developed. Congrats!

I've never seen a Video about a Pellet Hot end before. Awesome Video!

I hope that you keep pushing this method forward! 🎉