3d materials for sneaker soles

[tobielouw 0]

I’m embarking in a patent for a new sneaker related shoe sole but know nothing about rubber type materials not about using any design packages or modules focused on sneaker sole design.  I have an Ultimaker  S3 and design and print commercial use items using fusion360 and cura.  Can anyone kindly share insights in to where to begin.  Tx, Tobie

[tobielouw 0]

I need to design and print four different sneaker soles for testing (as my first objective).  Shore hardness around A40.  It is to be a single material for starters.  

[gr5 2,172]

40A is pretty soft.  Keep in mind you have to push this material through the bowden and if it's too soft it just is like pushing a rubber band through a hole.  It's going to get all wavy/kinky and fold over itself.

 

Googling found me this page.  Ninjaflex (shore 85A?) is the softest material I've printed and it was quite difficult.  I can't imagine pushing something even softer through the bowden. 

https://filaments.ca/blogs/3d-printing/15475957-shore-hardness-of-flexible-3d-printing-materials

 

I did see a 74A material here:

https://www.3dprinteros.com/what-is-the-best-flexible-filament-for-my-3d-printing-needs-my3dmatter-study/

 

For ninjaflex I had to print very slow (like 10mm/sec) and I had to add drops of oil to the filament once every meter so that it would easily glide through the bowden with minimal pressure.  Normally the feeder is pushing PLA through the bowden with incredibly high forces - like 10 pounds or 5kg of force - that's typical.  But that won't work for ninjaflex filament or even softer filaments.

 

I suspect that TPU which is significantly stiffer and easier to print (but makes great bike handle grips) might be good enough for the sole of a shoe.  Not sure.  According to that first page above, TPU is shore 95A.

[gr5 2,172]

On the second link above they mention that you can make things even more flexible with 3d printing because with 3d printing you don't have to (and usually don't anyway) make prints 100% solid.  So you can probably get away with higher shore hardnesses than you would use in a normal shoe product.  So I would start with TPU as it's very popular, Ultimaker I think sells a TPU filament and it's MUCH easier to print than the even-more-flexible filaments.

[geert_2 557]

If I had to do that, I would consider printing a mould, and then cast some sort of rubber (PU? - which exists in various hardnesses) into it. Or print a real model, print a shell, pour silicone in-between model and shell, and thus make a silicone mould. And then pour rubber into that silicone, to prevent it from sticking. Then you have the advantages of both 3D-printing and casting.