Ultimaker S3 - TPU 95A print

[Cerejo 0]

Hi Everyone!

 

I'm dealing with some issues when printing a bellows with TPU 95A.

 

The surface of the part containing the seam is very poor (pls see attached file - face of the seam).

The surfaces of other parts are not perfect, but they are better than the seam surface.

 

What are your recommendations for improving the surface containing the seam?

 

Machine: Ultimaker S3

Parameters: Ultimaker TPU 95A default (attached 3mf file)

Part thickness: 1.2 mm (3 layers)

Thanks!

 

UMS3_bellow.3mf

[gr5 2,224]

It appears the problems are on the overhanging surfaces and not the other surfaces.  This might be as good as you can get with this particular material and slope - I don't know.  TPU is not as easy as PLA or nGen.

 

Or do you only care about that "z seam"?

 

1) First I'd try printing MUCH slower to see what happens.  I'd try 1/3 the speed you are currently printing at.  It sounds horrible but I'd try this first.  You don't have to print the whole part - just print the first few folds and you'll know if it's better or not.  If that improves things then I'd speed it up slowly and look at other settings (accel control, tweaking the 7 or so speeds in cura settings).

 

2) You could try using a support material.  It probably looks equally bad on the inside so you need support material on both sides.  You could print the part on it's side but that would be a LOT of support material.  Ultimaker has this chart showing which support materials work with which printing materials:

https://ultimaker.com/learn/how-we-test-3d-printing-material-combinations/

 

It doesn't have an X but it does have an "experimental" for PVA and "breakaway".  not encouraging but it worked for someone I suppose.

 

Is this a prototype and will be printed with mold injection at some point?  Or is it for an in-house machine?  Or is this intended for a customer product?

 

Does it actually work fine but looks "ugly" or are you worried about customer expectations or are you just curious in general?

[Slashee_the_Cow 409]

11 hours ago, gr5 said:

1) First I'd try printing MUCH slower to see what happens.  I'd try 1/3 the speed you are currently printing at.  It sounds horrible but I'd try this first.

I can attest to this (and I print a lot of TPU, because I love making weird stuff - squishy, evenly weighted dice anyone?). I usually print TPU at about 20mm/s. Normally I tell people to follow the values printed on the side of the spool (or in a leaflet in the box) but TPU always prints much better at lower speeds. Makes layer seams a lot less visible, is more forgiving when it comes to seams in a layer, and the result is generally stronger - yes, I have put a piece printed out of TPU in a vice to make sure it doesn't go anywhere and grabbed a bit sticking out with pliers and pulled and twisted it as much as possible to try and break it (testing the strength of a print before giving it to my baby nephew as a present, don't want parts to come off). And it withstood all the energy I could muster to attack it, another test piece printed faster didn't survive.

[Cerejo 0]

Hi @gr5, @Slashee_the_Cow,

 

Thanks for your answers, they were very helpful.

As you mentioned, I managed the issue by slowing down the printing speed from 25 to 20 mm/s. I also changed the seam location.

The improvement is significant!! Some pictures are attached.

[gr5 2,224]

I'm very surprised that lowering by 20% was all it took!  I thought you would need to cut the speed in half as a minimum so this is great news.

[Cerejo 0]

@gr5 In my specific case, it worked.
Thank you for anserwing my question and pointing me in the right direction to solve it.