3 D Printing Materials

A collection of information about common 3D filaments used most often in e-NABLE

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Created by Ken Bice, last update (History) Public

TPU

TPU is Thermoplastic polyurethane. There is a similar material, TPE (ThermoPlastic Elastomer), that we will consider synonymous with TPU.

The key feature of TPU is that its printed parts can be anywhere from almost rigid to very “floppy”, based on the version of TPU that is used and the settings you use when printing.

TPU prints at nearly the same temperatures as PLA. It is recommended that the print speed should be considerably reduced - such as about half your normal print speed setting.

The three major factors that affect the rigidity of the print, in decreasing order of effect are:

  1. Shore hardness of the filament. This represents how hard the actual material is. Read more at this link: https://hub.e-nable.org/file/file/download?guid=01ca697d-f4db-4d14-8c9e-a2bbba57e5fb
  2. Number of perimeters. This is how many times the printer prints the vertical, outside-most structure of your model. More perimeters means a firmer part.
  3. Percent infill. Infill near zero will produce a spongier part than infill near 100%.

If you order a TPU filament from most all vendors, the shore hardness will likely be between 95A and 98A (Shore A hardness scale). You should assume that unless they advertise the shore hardness when you buy it.

TPU in the 95A to 98A is useful in many cases, assuming you modify infill and perimeter count to adjust to the level of firmness.

One common e-NABLE vendor of flexible filaments (e.g., TPU) is NinjaFlex from NinjaTek. I single them out because they produce TPU filament with Shore hardness as low as 85A.

For a better description of the different manufacturers and their products, check out this link describing “Best of” for TPE (TPU is a subclass of TPE): https://all3dp.com/2/tpe-filament-explained-and-compared/. That article mentions FilaFlex 82A, but Recreus - makers of FilaFlex - have now marketed even softer materials: FilaFlex TPE 70A and FilaFlex TPE 60A Pro.

To print flexible filaments requires special care, and likely special printer components.

  • The print temperature and bed heat are only slightly higher than PLA when printing TPU, but the print speed needs to be considerably slower - such as 15mm/sec versus a more standard 40-60mm/sec.
  • The filament channel, if possible, should be a direct drive (the extruder feeds directly into the hot end)
  • If instead the printer is a bowden tube feed to the hot end, replace the tube with the precision Capricorn PTFE tubing (https://www.filastruder.com/products/capricorn-ptfe-tubing?variant=45539850511). For example, if you use a Shore 90A or above material, you can likely get by with a standard filament channel but below 90A you should preferably be using Capricorn or equivalent.
  • The very best arrangement for printing flexible filament would be a dual gear extruder arranged as a direct drive delivery system.