rubber-like materials

[aag 6]

I need to join parts in a way that is moisture-tight. Not necessarily immersion-proof, but reasonably tight. Is there any way to print some kind of soft, rubber-like materials that would serve this purpose? I have an Ultimaker S5.

[Smithy 1,144]

You could try some of the flexible materials, like TPU95A from UM or Ninaflex which is much more flexible.

[aag 6]

Thank you! How do these compare to Hytrel, for which Ultimaker has just published a material profile?

 

http://www.dupont.com/content/dam/dupont/products-and-services/plastics-polymers-and-resins/plastics-polymers-and-resins-landing/documents/Hytrel_3D4100FL_NC010.pdf

 

I knew nothing about the Shore scale of hardness, but according to this synopsis: https://www.artmolds.com/shore-hardness

I am afraid that Shore 60D may still be too hard to work well in a waterproof joint.

[Smithy 1,144]

I don't know Hytrel, but these flexible materials are the only ones I know, that could help to be moisture proof. Waterproof is another requirement and they will not, because they are too hard, that's right.

 

I think it hardly depends on your model and what you want. Can you give an example what you want to do?

[Baychattan 1]

It depends on how you are intending to design the moisture-proof joint. There are two types:

 

O-ring - where a lightly-constrained seal is intended to move and deform to wedge itself into a small gap which it cannot get through. Increasing fluid pressure forces the seal into a tighter seal. There are two types of O-ring seal, face and barrel. Can take some movement of the items to be sealed. The seal material is relatively soft.

 

Gasket - where a seal is tightly constrained and pre-loaded/ compressed, and the seal is not intended to deform or move. Eg cylinder head gasket in a car engine. The seal material is relatively hard.

 

[SandervG 1,521]

From what I understand Hytrell is slightly more flexible (60), but perhaps TPU 95A is already flexible enough for you. Although 'reasonably tight' is pretty open to interpretation, I would say both have pretty good layer bonding and can be printed air-tight. 

[P3D 46]

Just for clarification, TPU 95A has 46 Shore D, so Hytrel is actually quite a bit harder. (See https://ultimaker.com/en/resources/49917-tpu-95a#technical ) Generally, a bowden-type printer (like all unmodified Ultimakers including the S5) isn't the best choice for flexible materials. You could get a sample of Ninjaflex, and try to print it with very low printing speeds. 

 

But first I would try TPU95A. This should work quite well for a gasket-type sealing, and prints reliably with the S5 (make sure it is dry, though).

Edited November 27, 2018 by P3D

[geert_2 557]

Why not simply apply a gasket-type silicone, before mating the parts? Like in automotive applications? That would fill all surface-defects like layer lines too.

 

If you want a removable gasket, use a non-stick silicone. Otherwise use a sticky one.

 

Note that most silicones are water-tight because they repell water. But they are not water-vapour tight. And they are not oil-tight: solvents, oils and liquid parafines leak straight through it.

 

[NBull 14]

I have done some prints in TPU 95A an I would not call it a robber more a flexible plastic. it is really hard especial for small prints. so if you are expecting to make a silicone like gasket this is far from.

 

it's easy to use and prints well on the S5 though. 

In my experience the top have more imperfections then the bottom, so if possible i would print it against a PVA surface to get the smoothest result.

[Smithy 1,144]

15 minutes ago, NBull said:

have done some prints in TPU 95A an I would not call it a robber more a flexible plastic. it is really hard especial for small prints. so if you are expecting to make a silicone like gasket this is far from.

It hardly depends on the object and on the infill pattern. I got good results with TPU95A when using only 5-10% infill with the default infill pattern for TPU95A.

 

Very thin objects a print solid with 100% infill and they are still flexible, but these things are only 1-2 mm thick.

[NBull 14]

It might be something in my settings thats of. but this is in TPU with 10% infill.

 

 

It can bend but it's not rubbery like. And when bending it's more like a sharp angle bend, not a soft curve like one who expect from a rubber material. Stretching the ring also requires a great effort to deform it. 

 

it might be that i'm doing it wrong, i like the material for what it is, but i would not call rubber

 

[Smithy 1,144]

No, you are absolutely right, TPU95A is a great material but it is not rubber like.

 

Maybe Ninjaflex is more like rubber, but I haven't tried it yet.