TPU 68D
A flexible, rubber-like material with a Shore hardness of 68D. Parts bend and compress without cracking and return to shape, so it suits grips, bumpers, seals, straps and protective covers. It is the firmest of the common flexible filaments: thin walls flex, thick sections stay stiff.
- Shore hardness
- 68D
- Tensile strength (XY)
- 22.4 MPa
- Elongation at break (XY)
- > 650%
- Density
- 1.26 g/cm³
Colours
A smooth, slightly glossy surface. Flexible parts show layer lines a little more than rigid ones.
- White
Good for
- Protective covers, bumpers and feet that absorb impacts
- Gaskets, seals and plugs that need to compress
- Straps, grips and hinges that bend again and again
- Wearables and parts that touch skin, with no sharp edges
Keep in mind
- Not for tight tolerances: flexible parts stretch and bend, in printing and in use
- Firm rather than squishy: a 68D wall only flexes when it is thin
- Supports are hard to remove cleanly from flexible parts, so design the part to print without them
- Prints slowly, so the machine time per part is higher than for PLA or PETG
Specifications
Typical values measured by the filament manufacturer on standard test specimens. A printed part behaves differently depending on its shape, infill and orientation on the plate.
XY: loaded along the layers. Z: loaded across the layers, which is always the weaker direction.
Physical
| Property | Test method | Value |
|---|---|---|
| Shore hardness | 68D | |
| Density | ISO 1183 | 1.26 g/cm³ |
| Melt flow index | 210 °C, 2.16 kg | 21.8 ± 0.3 g/10 min |
| Melting temperature | DSC, 10 °C/min | 183 °C |
| Saturated water absorption | 25 °C, 55% RH | 1.20% |
Mechanical
| Property | Test method | Value |
|---|---|---|
| Young's modulus (XY) | ISO 527 | 1190 MPa |
| Young's modulus (Z) | ISO 527 | 600 MPa |
| Tensile strength (XY) | ISO 527 | 22.4 ± 0.6 MPa |
| Tensile strength (Z) | ISO 527 | 11.2 ± 0.5 MPa |
| Elongation at break (XY) | ISO 527 | > 650% |
| Elongation at break (Z) | ISO 527 | 31% |
| Impact strength (XY) | ISO 179 | 124.3 kJ/m² |
| Impact strength (Z) | ISO 179 | 9.6 ± 0.3 kJ/m² |
Chemical resistance
| Property | Test method | Value |
|---|---|---|
| Water | Insoluble | |
| Oil and grease | Resistant to most | |
| Acids | Not resistant | |
| Alkalis | Not resistant | |
| Organic solvents | Not resistant to some | |
| Flammability | Flammable |
How we print it
| Layer heights | 0.12 – 0.28 mm |
|---|---|
| Infill | 15 – 60% |
| Wall loops | 2 – 4 |
| Nozzle | 0.4 mm |
| Largest part | 230 × 220 × 245 mm |
| Max overhang without supports | 70° |
| Max bridge length | 20 mm |
| Supports | Added where needed, removed before packing |
The values are for design reference and comparison only. They come from the manufacturer's data sheet and were not measured on parts we printed.
Documents
We print TPU 68D with Bambu Lab TPU for AMS filament. The manufacturer's documents are available here.