3D Printing using TPU

"shop-teacher" (shop-teacher) 04/20/2020 at 15:24 • Filed to: 3D printing for the greater good

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OK, 3D printers of Oppo, I have another question for you. We were asked by the hospital today if we had any TPU filament to try making a couple of test masks with. We do not, in fact I had never heard of it, let alone used it. I did a bit of research, and it seems possible, though not particularly easy. It seems as though I’d have to print at least 5 times slower than I’m printing with PLA. My printers (Makerbot Replicator 2) also have a non-heated bed.

So, I’m asking the experienced 3D printers among you, in your personal opinion, would it be advisable to get a roll (not my money paying for it) and give it a shot, or with my equipment is my time better spent making more masks out of PLA like I’ve been doing?

I’m all for learning a thing or two, but it seems like it may be more valuable for me to keep doing what I’m doing.

Thanks, you’re the best!

This is my production so far.

Tripper > shop-teacher 04/20/2020 at 15:42

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Is TPU the stuff they make phone cases out of?

jminer > shop-teacher 04/20/2020 at 15:57

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I’d be worried about TPU bed adhesion without a heated bed, but it may be doable. It requires a good deal higher nozzle temp than PLA, closer to the ABS range so it’s also kind of hard to print without an enclosure. You usually have to print it slow too, like 30 mm/s.

It’s a lot more flexible a filament and it’s what the CDC/FDA/NIH recommend printing these things out of so that’s likely why the hospital asked.

It’s the easiest flexible filament to print but definitely not easy to print.

Rusty Vandura - www.tinyurl.com/keepoppo > shop-teacher 04/20/2020 at 15:59

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What does “five times slower” mean? It takes five times as long?

When I saw your first post, the picture of what you were printing, I did not realize those were masks and I couldn’t guess what they were. Good on you. I’ve been sewing masks, gotta mail out three of them to another opponaut this afternoon.

Folding yet?

PyroHoltz f@h Oppo 261120 > shop-teacher 04/20/2020 at 16:02

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I’ve never used TPU for 3D printing, only for injection molding and there's quite a bit of fine tuning required to make good parts come out of the mold.

I would think TPU would bring all sorts of complications, compared to PLA printing. I can see how it’d be desirable though, being soft and flexible, the masks would conform to the wearer with more comfort.

Goo d luck!

PyroHoltz f@h Oppo 261120 > Tripper 04/20/2020 at 16:03

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Yes, TPU is what many cell phone cases are made from. It stands for thermoplastic  polyurethane.

Boxer_4 > Tripper 04/20/2020 at 16:05

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TPU (thermoplastic polyurethane) is a type of TPE (thermoplastic elastomer). It’s a rubber like material (usually some blend of a standard polymer like a styrene or polyamide with rubber) that shares a lot of processing similarities to polymer materials (can be injection molded, extruded, and more recently 3D printed). A lot of “rubber” products you interact with these days are TPEs due to ease of manufacturing.

shop-teacher > Rusty Vandura - www.tinyurl.com/keepoppo 04/20/2020 at 16:25

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Yes, it will take five times as long to print, and that’s best case scenario.

I do not have a computer hooked up at home at this time.  I’m just using my work laptop.

shop-teacher > jminer 04/20/2020 at 16:26

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That jives with what I’m finding. I don’t think I’ve got the proper artillery to pull it off.

shop-teacher > PyroHoltz f@h Oppo 261120 04/20/2020 at 16:27

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Thanks for the input!  I think it’s probably best to leave well enough alone.  These old Makerbots are doing a pretty great job with the PLA.  I’m not convinced they can pull off the job in TPU.

Tripper > Boxer_4 04/20/2020 at 16:55

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You a chemist?

Censored > shop-teacher 04/20/2020 at 17:23

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Im pretty sure you have to use a direct drive extruder/hotend as the tpu won't feed through the Bowden tube.

shop-teacher > Censored 04/20/2020 at 18:42

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That I have, but I think it's best to stick with PLA.

Boxer_4 > Tripper 04/20/2020 at 19:20

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I wish!  Mechanical engineer with a background in plastic materials and injection molding, currently working for a custom injection molding house.  

Jacob Beach > shop-teacher 04/20/2020 at 20:47

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One of the posts I saw was pointing out that TPU is really hydrophilic and might actually pose issues with sanitizing.

Those masks would be a 7 hr print in TPU as well- I was tinkering with the idea on a similar design.

When not printed perfectly tuned TPU ends up with a lot of holes as well, so this might not be the best learning scenario for dialing it in. With a geared extruder I can get professional results, with anything else there's a ton of clean up.

Censored > shop-teacher 04/20/2020 at 20:52

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I wasn't sure what the makerbot had.

shop-teacher > Jacob Beach 04/20/2020 at 21:19

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Thank you for the input. I agree, this is not the best learning scenario, and am going to stick with PLA. While I do have a direct drive extruder, it is not geared. I also don't have a heated bed.

facw > shop-teacher 04/22/2020 at 14:35

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BTW, more COVID-19 3D printing: https://www.washingtonpost.com/climate-environment/2020/04/22/nasal-swabs-shortage-coronavirus/

shop-teacher > facw 04/22/2020 at 15:30

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Cool!  We made out first delivery today.  124 masks, 107 ear guards, and I also gave the local senior center 54 pairs of new safety glasses I had on hand.