Exploring the Challenges of 3D Printing with Rubber

The Challenges of Rubber in 3D Printing

A friend and I have a shared project in mind: creating customized footwear using our workshop's new multi-material 3D printer. It seems like a perfect match, but unfortunately, we have run into limitations with this technology.

Rubber is the ideal material for creating supportive soles, but the most suitable types of rubber for this application cannot be 3D printed. I wanted to understand why, so I embarked on an intriguing journey that taught me things about 3D printing I was previously unaware of.

Consequently, I realized that rubber, unlike the polymers I am accustomed to, does not behave the same when subjected to heat. A standard 3D printing filament melts and flows from the printer's nozzle, but rubber does not behave in the same manner, making it difficult to use.

Rubber is a non-Newtonian fluid, meaning its viscosity changes under pressure. If I tried to push rubber filament through the extruder, it would become too viscous and clog the device. The closest alternative I could use is TPU (thermoplastic polyurethane), but even though it is flexible, it lacks the necessary adhesion.

So how can I then mold rubber? Searching online, I discovered that there are factories specialized in the extrusion and molding of rubber, but these items are not made using liquid rubber. Instead, shredded rubber is pressed into molds and then heated to fuse together, resulting in the desired shape. The process does not require extremely high temperatures, but it remains to be seen if it is feasible in a hacker workshop.

Thus, the question remains: who has truly experimented with rubber in this context?