The most flexible filament I tested so far: AzureFilm 85A

This 85A TPU filament is the most flexible filament I tested so far. I already tested filaments with similar hardness (85A on Shore A scale), but hardness is one thing, the flexibility other.
The filament is more than 2 years old, but it was stored in vacuum bags and it was dried before printing.

Contents:
0:00 Introduction
2:09 Drying
3:00 3D printing
6:03 Prolongation test
6:32 Tensile (pulling) test
6:45 Layer adhesion test
6:53 Ring test (compression)
7:14 Ring test (tensile)
7:43 Friction test
8:16 Washer test
8:54 Creep test
9:12 Temperature test
9:44 Results
12:31 Conclusions

#azurefilm #3dprinting #tpufilament #flexiblefilament

[Rippthrough]

The curling up happens because the TPU isn't fully melting in the nozzle, and when you put the perimeters down, the cooler core is retaining some tension and causing stress in the model - that pulls on the sharp corners and curls them upwards. The solutions are either slow down the print, increase the temperature, use a nozzle like a CHT or similar that can heat the filament more easily, or if your slicer has the option (Orca does) - use alternating reverse perimeters, so clockwise one layer, counterclockwise the other.
That won't remove it completely, but it will spread the stress across both corners instead of just the one and reduce the curling by about half.

You see it with other materials too, PET-G in particular will do it when printed at high speeds.

[karlosss]

I love the friction test for these types of filaments as its a material property not tested by many other prople (if any).

[diegovd]

Thank you for your time and hard work testing! :)

[dekurvajo]

Here is my idea about the lower temp curling. By printing lower temp, the tpu still sticks to each other, yet the surface tension is much higher than the warmer parts. Its like when you stretching dough. They are curling back on the end. But if you make it warmer (by the waemth of your hand) the tension force is getting lower. So they still flat on the table, and dont curling back at the edges.


And i think the extruder is able to push trough the material, even below its ideal viscosity point. So you actually sticking together a kind of flexed strings, and they start tp flexing back.

[Dramaican]

I think for flexibles lower print temperature means higher viscosity and increased internal stresses. The higher viscocity creates a small delay for when the stress (of the material being squeezed through a small nozzle opening) releases. I think those stresses create the curling up and especially for overhangs because the extruded line is less constrained by the previous layer so it has more space to deform from the released stresses. If you have ever noticed on silk filament that when you extrude in mid air (while loading/purging filament for example) right after the extrusion stops the extruded string of material becomes bigger in diameter and retracts/shrinks in length. That is stress release and you can easily see it because the extruded line/string is not constrained to a previous layer or the build plate. Stress release always happens, but if the material is stiff the previous layer limits the amount of defomation the stress/pressure release forces can introduce. In the case of a flexible material, the previous layer "moves" with the current layer as the material is still deformable even if has solidified/cooled down, because it is flexible...

[robertgubberiksson]

Tnx, your videos are really informative and appreciated, keep up the good work mate!

[edufonseca]

Great! Testing the exact Tpu shore i was looking for.

[hd-bedi]

At 220c the layer adhesion fails along the limited surface contact area from the overhang so the problem is both the low temperature and the overhang combination I think. If anyone has other opinions or thoughts please share!

[frankb]

I was honestly surprised at how easy It was for me to print the 85A filament I have. It helps if you have a large geared direct drive extruder. I found that I could still enable retraction with a short distance and a lower speed than I would use for normal filament. I also don't believe TPU needs drying.

[dekurvajo]

Thank you, i know it sounds weird but by look, this is the exact shore/flex ratio that i am looking for. Do you think it would be possible to print with Bowden or its a no-no?

[davidconner-shover]

I've been using 87a, it's been a bit of a challenge

[timhoover]

I just did a temperature tower with some silk PLA and noticed the same phenomenon about the overhang angle looked better at higher temperatures. The other features improved as well, so I'm not sure why that is...

[itsGeorgeAgain]

Give varioshore tpu a try. Its 99A unfoamed, and goes 55A if you foam it at 250c/60% extrusion multi

[mikestewart]

Get yourself some NinjaTek Chinchilla…

[marc_frank]

higher stiffness would be more useful, i think