Technical Specifications
Typical Applications
- Damping buffers and end stops in linear motion systems
- Seamless gaskets for HMI panels and control cabinet enclosures
- Protective workpiece nests and inspection fixtures
- Vibration pads in contact with oil and other media
- Contour-accurate case inlays for sensors and optics
Material Documents
Material profile
Foamed TPU is not a new polymer but a process: the filament contains a blowing agent that expands above a certain temperature. The outer walls are run so that they do not foam – the perimeter stays dense and smooth. Inside, printing runs in the expansion range with reduced material flow, creating a cellular structure.
The result is a sandwich without a joint: closed skin outside, foam inside, all from a single strand. Compared with the solid-printed equivalent this saves a substantial share of the part weight, and the core absorbs an impact over a longer travel instead of returning it.
Key figures by print temperature
Foamed TPU has no single set of figures: the nozzle temperature controls how far the blowing agent expands – and with it hardness, density and strength at once. The values below come from the manufacturer datasheet for Siraya Tech Flex TPU Air (specimens printed at each temperature):
| Nozzle temperature | 240 °C | 250 °C | 260 °C | 270 °C | Method |
|---|---|---|---|---|---|
| Hardness | 78 Shore A | 71 Shore A | 68 Shore A | 63 Shore A | ISO 7619 |
| Part density | 0.88 g/cm³ | 0.70 g/cm³ | 0.59 g/cm³ | 0.51 g/cm³ | ISO 845 |
| Vicat softening | 83 °C | 74 °C | 65 °C | 53 °C | ISO 306 |
| Yield strength | 6.3 MPa | 4.4 MPa | 3.4 MPa | 2.8 MPa | ISO 527 (X-Y) |
| Breaking strength | 10.3 MPa | 7.2 MPa | 5.0 MPa | 3.8 MPa | ISO 527 (X-Y) |
| Elongation at break | 629 % | 605 % | 547 % | 475 % | ISO 527 (X-Y) |
Printed without foaming the material sits at roughly 85 Shore A; the filament itself has a density of 1.15 g/cm³ (ISO 1183). Between “cool and tough” and “hot and soft” you therefore get the full 63A to 85A range – at roughly half the part weight.
A second material of this class, QIDI TPU-Aero, confirms the order of magnitude: hardness adjustable between 65A and 85A, part density 0.74 g/cm³, Vicat 70.4 °C, breaking strength 6.81 MPa and 576 % elongation at 250 °C.
What this means for engineering
Soft and light is not free: every extra degree lowers density and strength. A damper meant to absorb energy is printed hot; a gasket that has to hold sealing force rather cool. We set the temperature from the load case and record it for repeat orders.
Design notes
- Define wall thickness deliberately. The dense skin is only as good as its thickness – sharp edges and tight radii need more reserve than flat areas.
- Plan dimensional tolerances. Expansion affects outer dimensions; tight fits are sampled on a first article.
- Keep fine detail in solid zones. Thin ribs, lettering and narrow sealing lips blur in the foamed region.
- Separate load introduction. Screw connections run through solid sections, threaded inserts or a backing plate – not through the foam.
Compared with solid TPU
Solid TPU remains the better choice for tight fits, high surface pressure or wear edges. Foamed TPU plays to its strengths where damping over a short travel, low weight and a cleanable surface come together.