# TPU

Thermoplastic Polyurethane (TPU) has revolutionized 3D printing with its unique blend of rubber-like flexibility and industrial-grade durability. Known for its shock absorption, chemical resistance, and stretchability, TPU is the go-to filament for functional parts that demand elasticity without sacrificing strength. From custom phone cases to automotive seals, TPU unlocks applications where rigidity fails.

<figure><img src="/files/cFNSphp06Sd0tABEwbW5" alt=""><figcaption><p>PolyFlex™ TPU90 being used as a bumber for an RC car</p></figcaption></figure>

### **What Is TPU?**

TPU is a flexible thermoplastic elastomer (TPE) that combines the elasticity of rubber with the printability of plastic. Unlike rigid filaments, TPU can stretch up to **500%** of its original length before breaking, making it ideal for bendable, impact-resistant components. Its durability against abrasion, oils, and low temperatures further cements its role in industrial and consumer applications.

How soft the TPU will be will depend on the Shore Hardness of the material being used as well as the infill % used for the model.  A lower shore hardness = a softer material. &#x20;

### **Printing with TPU: Techniques and Tips**

TPU’s flexibility requires adjustments to standard printing workflows. While challenging for beginners, mastering its quirks yields unparalleled results.

### **Optimal Settings**

* **Nozzle Temperature**: 210–250°C (varies by brand; start at 230°C).
* **Bed Temperature**: 40–60°C (heated bed improves adhesion).
* **Print Speed**: 15–40 mm/s (slower speeds prevent filament buckling.  Particularly true for softer TPU options)
* **Retraction**: Minimal (1–2 mm at 10–20 mm/s) to avoid clogging.
* **Layer Height**: 0.2–0.3 mm for better layer adhesion.

### **Hardware Recommendations**

* **Extruder**: Direct-drive systems outperform Bowden setups, reducing filament path friction.
* **Build Plate**: PEI sheets, painter’s tape, or adhesive-coated glass enhance first-layer grip.&#x20;
* **Cooling Fan**: 20–50% to balance detail and layer bonding.

### **Common Challenges**

* **Stringing/Oozing**: TPU’s elasticity causes fine hairs; reduce retraction and slow travel speeds.
* **Moisture Sensitivity**: Store filament in a dry box and pre-dry at 50°C for 24 hours to prevent bubbles.
* **Bed Adhesion**: Over-sticking can damage surfaces; use glue sticks as a release agent.

### **Advantages of TPU**

1. **Elasticity**: Stretches up to 5x its length without breaking, ideal for seals, grips, and wearable tech.
2. **Durability**: Resists abrasion, oils, fuels, and impacts, outperforming rigid plastics in harsh environments.
3. **Shock Absorption**: Dampens vibrations for automotive mounts, prosthetics, and sporting gear.
4. **Chemical Resistance**: Withstands industrial solvents and UV exposure, suitable for outdoor use.
5. **Custom Flexibility**: Adjust infill density (10–20% for softness, 50–100% for rigidity) to tailor part performance.

### **Limitations of TPU**

1. **Print Complexity**: Requires slow speeds, precise retraction, and moisture management.  Support structures can often be very difficult to remove.
2. **Post-Processing**: Difficult to sand or smooth due to abrasion resistance; limited to trimming or tumbling.
3. **Not Food Safe**: Unsuitable for kitchenware without certification.
4. **Hardware Demands**: Bowden extruders may struggle; direct-drive systems are preferred.

### **TPU vs. Other Flexible Filaments**

| Property                | TPU       | TPE         | Silicone      |
| ----------------------- | --------- | ----------- | ------------- |
| **Elasticity**          | High      | Higher      | Extreme       |
| **Durability**          | Excellent | Moderate    | Moderate      |
| **Printability**        | Moderate  | Challenging | Not Printable |
| **Chemical Resistance** | High      | Moderate    | High          |

### **Applications of TPU**

* **Consumer Goods**: Phone cases, watch straps, shoe soles, and custom grips.
* **Automotive**: Seals, gaskets, vibration-dampening mounts, and hose connectors.
* **Industrial**: Conveyor belts, drive components, and non-marring tool covers.
* **Healthcare**: Prosthetics, orthotic insoles, and flexible tubing.
* **Aerospace**: Shock-absorbing pads and protective housings.

### Requirements to Print TPU

This can depend on the specific blend of TPU being used.  Generally speaking though - when printing a soft version of TPU - a direct extruder will be required.  Slower print speeds will also be required, and if printing above 240°C, an all-metal hotend is required.

{% embed url="<https://www.youtube.com/shorts/z_kpLSqBYjE>" %}


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