TPE warping problems

Question

I'm attempting to print some flexible TPE filament. But I failed to imagine TPE was this difficult to print.

Specs of the shop-brand filament:
Red 1.75 mm TPE (+-0.05 mm).
Hardness: 45D.
Print temperature: 220-260 °C with 0-95 °C bed.

I'm trying to print this on my original Prusa i3 MK3S with powder coated sheet with 0.20 mm layer with PrusaSlicer 2.0.0.

What happens? After 3 or 4 layers, the print warps a lot and detaches from the plate. The object is 40 mm long. The next image shows the print detaching from the build plate as well as a skirt of two layers height:

I've tried warmer/colder, more/less fan, faster/slower. I went down to 1 mm³/s, which is 7 mm/s. For reference, PLA prints 15 mm³/s.

I readjusted my z-cal, and when I test print a first layer with TPE it's difficult to remove from the bed.

I also attempted the glue stick on smooth PEI sheet. Worked until the first few layers of infill, then it still warped.

Do I have bad filament with too much shrink, poor settings or is this 45D just too soft for my MK3s?

Bonus pile of failures:

Answer 1

I have not given up yet!

And I figured it out, I think. I tried many things, dried the spool at 60C for an hour, Simplifiy3D's slicer, but eventually playing around I found a setting that resulting in no warping during the print.

Final solution:
- Original Prusa Powder Coated sheet.
- Changed the nozzle to 0.6 mm.
- 20 mm/s print speed, slow.
- 260 C nozzle temp, make it liquid to get best bed adhesion.
- 90 C bed, this keeps it soft at the bottom. Do not change the temperature, as this will detach the print.
- 0.95 Extrusion Multiplier instead of 1.2

The extrusion multiplier did the trick. It kept pushing slightly too much stuff out, especially on the bottom layers causing ridges that is will pull on the next layer.
It did still warp a bit, I found that this stuff shrinks about 2% when cooled, and when you start infill, it will pull itself loose. Hence the 90C bed temp.

It still prints poorly, but it did print without creating "the blob"!

Answer 2

I had a devil of a time getting this "greasy" tpe85a to print from filaments.ca. Buried in the comments there:

85A TPE Warping issue:

Mesa K wrote on Filaments.ca to try the following:

"Adhesion: this stuff does not stick to Prusa's smooth PEI sheets at all, it also did not stick to masking tape either. The solution I found was to tape a piece of printer paper to the bed (I used packing tape for this, but I would recommend masking tape or something else easier to remove). I didn't have a glue stick or kapton tape to try, but those may work too."

That's right, printing on a sheet of printer paper creates amazing adhesion for this stuff. I suspect it to be a bit of a "greasy", oily filament at temp. When you drop a piece of popcorn on a sheet of paper, it leaves a grease slick. It is a permanent stain. So if this filament is a bit greasy (but much higher viscosity than melted butter ;-] ), literally, at temp, the paper would actually act as an absorbent material, and even as a degreaser on the point of contact with the filament.

I am printing a phone case. I assume you have used a sheet of paper on top of this sheet of paper and leveled the bed perfectly using the paper as feeler gauge method, or all the rest of this advice is useless. Because of the close tolerances I use on the first layer, this is critical.

Tips: Print a huge 1 cm brim in case you have to do last ditch intervention on the print. The brim is to prevent warping from the contact surface, but also as a place to tape the print down from the topside in case it decides to warp no matter what you try.

Extrusion: I am using a creality CR10V2 I converted to direct drive with a 0.2 mm nozzle. I replaced the stock stiff spring with a pair of ballpoint pen springs I hotglued together. ( I am kind of a barbarian.....) They put just enough tension on the tensioner wheel to reliably push the filament without it sticking to the drive gear. (Single drive gear extruder)

Set Cura to extrude at 112 % or in that range. It will not blob at that rate, but will have a nice fat line laid down. It created blobs for me at 115 % extrusion, so avoid going to 145 % like I tried at one point. Nice to know my ballpoint pen printer can do that....

The initial layer height will be set to 0.12 mm, with following layers set to 0.19 mm.

The wall width will be 0.2 mm and that "excess" in the above calc fills gaps and binds two side by side lines together.

This stuff also contracts if the adhesion sucks, so extrude extra and it will not contract lengthwise so badly.

Heat:

Extruder: 220 °C. My filament seems to get more plastic-y at higher temps. Lower temps made a softer, more flexible material. Also, printing at a lower temp reduces contraction related warping.

Heat Bed: 85 °C. Keep it there the whole print. This stuff likes the warm and contracts less if kept warm the whole print. I tried starting at 85 °C and letting it cool after the first layer to 40 °C, and all 4 sides came loose from the painters tape surface. Keep it hot!

Increasing your fan speed seems to help it contract as soon as it is laid down, laying a bead that has already contracted somewhat by the time it is embedded in the layer.

Other tips: Printing infill at 25 mm/s was too fast. I have it making nice prints at 18 mm/s throughout the print. TPE prints slow. Fails print slowly too. Lots of beautiful failures on the path to success... Knowledge gained from watching the machine print.

The above guidelines will help you get prints without glue, sometimes with a bit of tape around the brim if it is really cranky. Good luck, very tricky material to work with on large surface area prints.