Complete Guide to TPU 3D Printing

When you think about 3D printing materials, rigid materials like PLA, PETG, ABS or ASA are most likely to come to mind. However, sometimes your application demands components that are flexible and can bend or compress under stress.

The answer to this is TPU. Thermoplastic urethane and thermoplastic elastomers as a class of materials allow you to design complex ductile components in the exact shape and color you need. It creates innumerable opportunities for manufacturing industries which explains its growing popularity.

This comprehensive TPU 3D printing guide gives you a rundown of everything you need to know to 3D print this versatile filament.

What Is TPU?

Thermoplastic polyurethane (TPU) is a block copolymer belonging to the thermoplastic elastomer family. The material combines the useful properties of both rubbers (thermosets) and thermoplastics and offers the following properties:

Flexibility: TPU is perfect for applications requiring materials that stretch without breaking. This copolymer can regain its initial shape after being deformed, which can be helpful for manufacturing components such as flexible tubing or protective cases.

Elasticity: The elongation at break typically ranges from 300% to 600%, This means that TPU can stretch considerably before failing, making it a better choice for flexible uses than many other materials like PLA (Polylactic Acid) which shows much lower elongation properties.

Durability: The material has high resistance to abrasion, oils, and greases. Its tear resistance ranges from 80 to 200 kN/m, making it suitable for demanding applications such as automotive components, footwear, and industrial parts. Moreover, TPU maintains its integrity under dynamic loads, which is essential for products subjected to repeated stress.

Why Use TPU for 3D Printing?

Here are some of the most important reasons why 3D printing with TPU has become so popular:

Flexibility and Resilience: TPU 3D printing allows you to create parts that can bend, twist, and compress without breaking. Thanks to its resilience, this material can stretch and return to its original shape without any damage.

Durability and Resistance: TPU can be used for manufacturing parts that are exposed to friction or frequent use, as it is highly resistant to abrasion and wear. What’s more, it can withstand contact with various chemicals, including oils and solvents.

Suitability for Specialized Applications: TPU is available in different colors and shore hardness levels, so it can be easily customized for various applications. Due to its biocompatibility, it is also suitable for medical applications.

BigRep TPU 98A 3D Printed Softjaw Tooling

Techniques in TPU 3D Printing

You can use the TPU material for 3D printing using one of the two following methods:

TPU 3D Printing Using FFF

A Fused filament fabrication (FFF) printer is a budget-friendly option for an entry-level workflow, so it is a popular choice for businesses who want to start printing with TPU. This filament can be really helpful for improving design concepts and prototypes. It is particularly important if you plan to manufacture your products on a mass scale using traditional injection molding methods in the future.

However, you need to keep in mind that it may not be that easy to 3D print with TPU on FFF 3D printers. The filament is soft and stretchy, which can potentially clog the extruder and cause technical problems. To avoid this, choose a 3D printer that is well-designed for printing TPU. A robust feeding mechanism in the extruder, like dual-drive feeding wheels, can alleviate this. Also, look for a 3D printer with a shorter filament path so the spool remains in closer proximity to the extruder.

Also, take into account that FFF-printed TPU components are anisotropic, so their strength will be different as you change axes or planes of stress. TPU parts are often used for applications including pulling, compressing, twisting, or stretching, so this property can be challenging if a component needs to be functional.

Printing with TPU - an airless bicycle tire 3D printed by a BigRep large-scale FFF 3D printer

TPU 3D Printing Using SLS

If you want to use TPU for more functional applications and higher throughput, SLS technology is more recommended than FFF. Even though it can be a bit more expensive, it allows you to benefit the most from the TPU’s flexibility and strength. Using it, you can manufacture strong, durable, elastomeric components, excellent for applications requiring complex geometries.

Thanks to SLS printers' self-supporting nature, you do not have to use any additional support structures, and you can easily achieve intricate geometries, including latticing, internal channels, or manifold-type accordion structures.

What’s more, an SLS system offers low refresh rates that increase its affordability and scalability. In this way, you can be sure that the powder is used efficiently and you do not spend on new materials more than necessary.

The downside to 3D printing TPU with an SLS machine is limited part size. The largest SLS 3D printers only offer around 150 liters build volume, while FDM 3D printers are available in much bigger sizes. For example, the BigRep ONE has a one cubic meter, or 1,000 liters, build volume.

TPU 3D Printing

Here’s what you need to do to 3D print with TPU:

1. Preparation

a. Choose the right TPU filament: TPU comes in different degrees of hardness,. Softer TPUs are more flexible, and harder ones are more rigid. Select the type that best suits your needs. Consider the brand as well, as some (like BigRep) are known for easier printing.

b. Prepare your 3D model:
Design or download the 3D model you want to print and make, making sure it is optimized for 3D printing.

2. 3D Printer Setup

a. Level the bed: The nozzle needs to be close enough for good adhesion but not so close that it blocks filament flow. Use the printer's leveling system or manual leveling to make the necessary adjustments.

b. Clean the bed: Use isopropyl alcohol to remove any oils or debris for good adhesion. For better results, you can use a PEI sheet or glass bed.

c. Check the nozzle: Make sure your nozzle isn't clogged. If so, do a cold pull or use cleaning filament to clean it.

d. Adjust the settings:

- - - Print temperature: Typically, TPU prints at moderate temperatures (225°C to 250°C), but check your filament manufacturer's recommendations to make sure.
    - Bed temperature: Usually, 40–60 °C is most recommended.
    - Retraction: To avoid stringing and clogging, use a minimal retraction distance (1-2 mm) and a slow retraction speed (10-20 mm/s).
    - Cooling: TPU printing typically works best with minimal cooling, so set the fan to run at about 20-30% of its capacity.
    - Layer height: 0.2 mm and 0.3 mm is most recommended for 3D printing with TPU.
      Print speed: Fast speeds can lead to jams, so make sure it is 5-30 mm/s.
    - Infill density: 20%–50% offers the best balance between strength and flexibility in TPU 3D printing.

The BigRep ONE large scale 3d printer's user interface

3. Printing

a. Load the filament: Load your TPU filament into the extruder, following your printer's instructions.

b. Monitor the results: Watch the first few layers closely to ensure good adhesion and no jams.

4. Post-Print Care

a. Cool Down: Let the print cool completely before removing it from the bed to prevent warping.

b. Remove the Print: Use a spatula or scraper to carefully remove the print from the bed. If you have a flexible print bed surface, you may find that TPU prints require some extra effort to remove compared to more rigid materials.

c. Store TPU Properly: TPU absorbs moisture, so make sure to store it in an airtight container with a desiccant pack to keep it dry. You can also invest in a filament dry cabinet such as the DRYCON that stores and dries your filaments so the material is good to go whenever you are.

Filament dryer - the BigRep DRYCON 3d filament dryer's Active Air Exchange Cycles

Tips to Successfully 3D Print with TPU

To get the best results from your TPU 3D printing, follow these tips:

Don’t go below the minimum wall thickness: The minimum wall thickness for 3D printing with TPU is 1.5 mm. Components with such walls can be very flexible, but to make them more rigid, it is recommended to increase the thickness to at least 3 mm.

Minimize retraction: Due to the TPU’s high flexibility, retraction can be really problematic. Always remember to disable or minimize it to prevent jams.

Choose a direct drive extruder: If you have a choice between a direct drive extruder and a Bowden, always pick the first one. It will help you keep your parts smooth and protect the TPU filament from bucking.

BigRep PEX2 - a direct drive extruder

Reduce cooling: Too much cooling can cause poor layer adhesion, so remember to keep it low.

Dry the TPU filament: TPU tends to absorb moisture quickly, which can worsen the printing quality. Always dry your filament for a few hours, or use a filament dryer before you print.

Set the minimum feature size: The minimum size for TPU components should be 0.5 mm. However, if you want to increase the visibility of engraved and embossed details, keep the height and width at least 1.5 mm.

Provide good bed adhesion: A PEI sheet is generally recommended for improving the adhesion in TPU printing, but you can also use a thin layer of glue stick. It will make the first layer stay in place and protect your project from warping.

Applications of TPU in 3D Printing

Due to its versatility, the TPU material is widely used in 3D printing for many different purposes. Some of its most important applications include:

Rapid Prototyping

Thanks to TPU 3D printing, businesses can reduce the lead times and costs associated with prototyping.

This technology allows them to experiment with new designs and geometries quickly without spending a lot of money and time on outsourcing this task. They can do it in-house and conduct as many trials as necessary to get the best results.

What’s more, 3D printing with TPU allows them to create intricate designs and complex geometries that are difficult to manufacture using traditional methods. For this reason, this technique is a go-to for many companies that need rapid prototyping for serial production.

Medical Components

Interestingly, due to its biocompatibility, TPU 3D printing is widely used in the medical sector to make, for example, orthopedic models and prosthetics.

Automotive Parts and Protection

As TPU is highly resistant to greases and oils, it is perfect for the automotive industry. It can be used to produce gaskets, plugs, tubes, seals, and protective components.

TPU 3d printing - 3D printed airless tire for NERA eBike.

A 3D printed TPU airless tire for the NERA eBike.

Industrial Components

3D printing with TPU can be used to produce durable parts with rubber-like qualities, such as elasticity, shock absorption, and vibration dampening.

As a result, it is excellent for producing seals, gaskets, flexible valves, shock absorbers, hoses, friction pads, protective coverings, and more. For this reason, it is widely applied in the manufacturing industry.

BigRep 3D printed TPU gasket for custom industrial parts or on-demand spare parts.

Consumer Goods

As TPU 3D printing offers flexible design options and opens a wide range of possibilities for customization, it is widely used for producing consumer goods, such as accessories, footwear components, and wearable garments.

Comparing TPU with Other Flexible Materials

Here’s how TPU compares to other 3D printing filaments

	TPU	PLA	ABS
Stiffness	Flexible	Rigid	Moderate
Glass Transition Temp (°C)	-30	60	105
Ease of Printing	Moderate	Easy	Moderate
Chemical Resistance	High	Low	Moderate
Durability	Very high	Low	High

Conclusion

tpu 3d printing - NERA's airless bike tires 3d printed by a BigRep machine

Using TPU filament for 3D printing offers excellent flexibility and durability, so it is no wonder that it is commonly used for a wide range of applications, including medical components, consumer goods, industrial parts, or functional rapid prototypes.

For personal projects or very large 3D prints, FFF printing is a sufficient, budget-friendly choice, but if you need higher part precision, SLS 3D printing is a better fit.

To get the best results, it is recommended to invest in high-quality machinery from a reputable manufacturer. By choosing BigRep, you can be sure you get professional 3D printers that reliably print TPU to ensure optimal performance.

If you are unsure which machine is best for your TPU 3D printing needs, fill out our contact form and an expert will get in touch with you!