So I was planning to buy some TPU for a few projects, but have been hesitant until now because I cant really picture how hard / flexible the material will be to plan any actual usage.
Images and scales that try to represent this havent really helped me that much either.
But then I stumbled on this video, which seems to show a TPU material that can, based on its flow rate / temperature (or simply underextrude from my understanding), dial in the Shore hardness.
So my question would be, as I know next to nothing about TPU, would this be possible with âTPU for AMSâ as well, to potentially get softer / squishier prints out of it?
Hi, no, thatâs a special type of material, a foaming TPU. There are a couple other brands that offer something like that as well, but not Bambu. Iâve been looking forward to trying some out. Looks like it takes some effort to dial in, but the possibilities are pretty cool (eg. varying density models).
TPU for AMS has a set hardness, which isnât all that soft really. You can kinda sink a fingernail a little into a solid surface, and itâs relatively flexible when printed thin. I compare it to something like lids for plastic/glass food containers, which have a built-in lip/seal and press on w/out any extra clips. In fact I may try to make some replacement lids out of it, like for the 21-cup Rubbermaid bins Iâm using as dry-boxes.
Anyway, other âtypicalâ TPU all has a set hardness and thatâs all you get. I hear you on trying to decide⌠had same issue, and no stores in my small town stock any filament at all. Just got a few spools over time to try out for myself.
I should probably add that with any TPU you can change the âsquishinessâ of an object by varying the density of the fill and/or wall count, to a point. True with any material to a certain extent, but especially so the softer the material is. But this doesnât change the basic properties of the material, like density or harness factor, as one could with a foaming material.
There are some other materials where the density/volume can be changed by varying parameters, like Bambuâs âAeroâ ASA and PLA, but these are more rigid materials to begin with.
thatâs a special type of material, a foaming TPU
Thanks for telling me, though he said it in the video, I didnt register that this was a distinctly different type of sub-material thats specifically made to foam / expand like that.
with any TPU you can change the âsquishinessâ of an object by varying the density of the fill and/or wall count, to a point.
Good to know that its still possible to get somewhat softer results if less densly printed, even if it wont apply to things like thin layers added on top of other parts for grip (i.e. bycicle handle covers).
Actually, I believe this methodology CAN be used to assist with the problem of TPU for AMS. Iâve been using Siraya Techâs foaming TPU since its release and have a belief that seems like it should translate to the issues we have. Follow me.
So, the change in temperature is only a portion of the reason the print comes out softer. Honestly⌠I believe it is a small factor. The real reason it comes out softer is, the print has twice as many air pockets. They literally remove 50% of the density of the material (or more) to make it softer while raising the temps. This suggests that if you were to have a foaming hard TPU/PEBA that is AMS compatible (68D or 72D), the softness can be substituted with the low density during printing, basically giving the illusion of a soft material. Note, this can not be done with the current TPU for AMS. That stuff has poor adhesion, and I assume the porosity would only make it worse. But if you use a more conventional 68D blend with the foaming elements, I imagine it would work well. I estimate they seem to be able to drop 20-30A worth of hardness with the foaming, this should get a hard TPU in the window of conventional 90A-95A hardness.
Granted this doesnât come at no cost. The foaming TPU gets softer by creating air pockets, which means it will not be suitable for water/air tight construction. It will have lots of porosity. Personally, I prefer the porosity, but I understand that is a draw for some.
Iâm just waiting for a manufacturer to come to the same understanding or explain why it doesnât work out. But I feel like it will be explored soon if it hasnât yet. Just seems like the next logical step.
Right, having an easier to handle material which achieves the same, or similar, qualities to harder-to-handle materials is a good thing. That appears to be one of the attractions of the current foaming offerings, like getting 80A-grade softness w/out dealing with the wet noodle factor. I got confused a little, in the first sentence you mean a TPU that can be used in an AMS vs. Bambuâs current âTPU for AMS,â right?
Also, how do you like the one youâve been using? Hard to dial in?
I think it can be thought of as either. TPU for AMS or just hard TPUs the feed well.
As far as the foaming TPUs and PEBA, they are great. Best use of TPU Iâve had. The Siraya Tech profile needs a little love (oozes and strings slightly) but it is pretty rock solid. It prints very high speed for a soft TPU (around 9mmÂł or around 170mm/sec). However, it is a pain to setup initially though. Bambu doesnât make using custom user profiles easy. I have to re-figure out how to get the profile to show up every time I use it. And like I said, the creation of the Siraya Tech profile is tedious but its worth it. Siraya Tech suggests creating a dummy print and replacing it with yours (likely to avoid the odd User Profiles).
Iâm mostly using the Foaming TPU Air at the 65A setting (softest), so the only tedious thing now is enabling the profile in the slicer. Basically the material comes out like Neoprene. Really cool material. Great for grips, pads, and soft touch surfaces. I picked up some PEBA Air for high temp multi-material use (Foaming TPU Air for low temp material mixing like PLA and PETG), but havenât cracked it open yet.