HOW TO PRINT WITH FLEXIBLE TPU FILAMENTS

TPU filaments (Flexible filaments) are basically plastic materials with characteristics similar to rubber, and this makes them extremely flexible and resistant. THE flexible filaments they are commonly used to produce household appliances, toys, phone covers, wearable items such as bracelets, car parts and medical supplies. If you want to 3D print an object that needs to bend, stretch, or compress, this TPU 3D printer filament should be up to the task.

Designers and engineers exploit the flexibility of flexible filaments every day and use them to create elastic shapes and prototypes.

Printing TPU filaments and other flexible materials can be a little challenging for those new to 3D printing, as they are not as easy to use as other filaments. With the right instructions anyone can achieve the desired results, which is why we have prepared some tips on how to print TPU filaments.

What are Flexible filaments?

THE Flexible filaments they are materials that combine the properties of rigid plastic and rubber. This mix is ​​known as thermoplastic elastomer (TPE). These rubber-like thermoplastic elastomers can be twisted and stretched without breaking, similar to how rubber behaves.

Some flexible filaments are more elastic than others and they all come in different types. The best known is thermoplastic polyurethane (TPU). TPU filament is slightly stiffer, which is an important feature in the 3D printing industry because it means it is easier to 3D print. It is also a little more durable and can better retain its elasticity in the cold. The wear resistance of TPU filament is 20% better than ABS filament and 70% compared to PLA filament .

Pros and Cons of Flexible filaments

Pro

• Excellent elasticity – It is ideal for those looking for a filament that can be bent, stretched and manipulated.
• Impact resistance – Products printed from flexible filaments are usually not significantly affected by impacts.
• Reduced vibration – Materials that have rubber-like properties dampen vibrations, making them ideal for industrial or mechanical parts.

Against

• Printing it is more difficult. It takes some time to get used to the characteristics of TPU filament if you are used to PLA filament. It tends to tighten, which makes decorative prints more difficult. The protrusions are quite difficult to integrate smoothly.
• Absorbs moisture – the filament is particularly hygroscopic; it is very important to dry it with a filament dryer before each use
• Post-processing. Prints made with TPU usually offer fewer options in post-processing.

Common Applications of Flexible Filaments

TPU materials can be used in a variety of ways. Among these are;

• Suitability Test and Functional Prototyping. Parts or products created with elastic properties can be tested for flexibility in real life.
• Custom tools. You can create tools with ductile parts with flexible filaments, such as grip parts or handles.
• Designed for end use. Some parts can be used normally or as spare parts due to their rubber-like properties. To prevent machinery from damaging goods on production lines, materials like TPU offer softer contact points.

Tips for Printing with TPU and common mistakes you make when printing

• Since there are several flexible materials on the market, it is essential to check the settings recommended by the manufacturer.
• If you print with flexible filament, it's often best to use a slow speed. Since the material is elastic, any sudden change in print speed can cause the part to become ungovernable. The filament can be compressed if the print speed increases, causing jams. For this reason, 25-35 mm/s is a good starting point.
• The flexibility and elasticity of TPU make it particularly sensitive to movements such as retractions. Accordingly, the retraction settings for the TPU filament must be optimized to limit movement in 3D prints. We recommend turning retraction off completely.
• If you don't have a direct drive extruder, we suggest using 98A hardness TPU filament.
• Before using TPU filaments, dry them with a filament dryer .

The most frequent errors that occur when printing;

• There is not enough adhesion between the first layers of hot filament and the printer base. This can result in a distorted 3D product. We suggest you use it Dimafix spray or, if possible for your printer, use one PEI plate .
• The filament cannot be extruded correctly from the 3D printer . This can happen if the nozzle completely blocks the process or if there are oscillations in the feed rate. If your printer has a Bowden-type extruder, it is best if you use harder TPU filaments (like 98A) and turn off retraction.
• The filament was not dried before use. THE flexible filaments they are very sensitive to humidity, so it is very important to always store them in a place where there is no humidity, preferably in a plastic or nylon box. Before each use, the TPU filament must also be dried in a filament dryer .

AzureFilm Flexible filaments

Azure Films TPU is available in two types which are: Flexible filament with 95A Shore hardness and Flexible filament with 85A Shore hardness. These flexible filaments are produced in Slovenia and are available in different sizes.

The strength, flexibility and durability characteristics of Azurefilm filaments make them a great choice for flexible film applications that require more strength. Unlike vinyl, TPU does not contain plasticizers, so it does not become brittle or lose its performance over time.

AzureFilm TPUs offer superior resistance to oil, grease, lubricants and fuels, as well as exceptional resistance to hydrolysis.

The flexibility of Azure filaments distinguishes them from other materials. The Shore of the material is a measure of its resistance to indentation and its flexibility. Typically Shore A or Shore D is used to describe the hardness of flexible materials. Flexible filaments used in 3D printing are measured on the Shore A scale, while harder rubbers are measured on the Shore D scale. Shore A is softer, more flexible and offers everything needed to meet the demands of 3D workers . Shore D is harder and also easier to 3D print. Its degree of hardness compensates for its shortcomings, making it ideal for starting to print with flexible filaments. It is very similar to Shore 98A.

How Different Extruders Affect TPU Printing

The extruder is an essential component for a 3D printer, which affects the performance of printing with flexible filament. You need to know how the extruder works and how you can optimize it so that the printing process produces the best possible results.

The job of a flexible filament extruder is to push the filament to be extruded and melted into a heated nozzle. The extruder is made up of three identical components: the driver gear, the stepper motor and the idler. The extruders always consist of the same components but are available in different types: Direct drive and Bowden. It is the path of the filament and the distance of the filament before entering the heated nozzle that distinguishes the two types.

Compared to direct drive extruders, the filament travels longer to the nozzle in the Bowden system, which increases the speed of 3D printing. Direct drive extruders are a preferable choice for printing flexible filaments because the position of the extruder is better and the chances of the print going wrong are lower. If we compare the Bowden system, the filament has to travel further to the nozzle, making it more likely that softer filaments will have trouble maintaining the correct shape.

So Bowden extruders work well with rigid materials like ASA , PLA , ABS , PETG , Nylon , Carbon Fibre and other filaments.

The extruders direct drives are particularly popular. Using this extruder allows you to have precise control of retraction, which is one of the main advantages. The location of the direct drive is important to ensure we can achieve smooth and accurate 3D prints as it minimizes the distance to the hot bed.

Direct Drive systems have the disadvantage of making the arm heavier, which can cause more backlash and vibration at higher speeds. However, a DDE system operating on a rubber 3D printer will often print at slower speeds due to limitations of the printer's other hardware features and assemblies.

How to Print Flexible TPU Filament with an Ender 3/ Ender 3 pro/ Ender 3 v2

The TPU printing with the Ender 3 PRO or Ender 3 V2 has been the subject of discussion about the Ender 3's extruder and whether the filament can bend once the filament gets past the toothed gear in the cold end. Because the flexible filament bends, the extruder motor has difficulty transferring the motion of the filament correctly.

Using an extruder with a direct drive motor is highly recommended if you want to 3D print softer filament. It is still possible to obtain good quality models using a Bowden extruder, if your Ender 3 V2 is set up and calibrated correctly. To optimize your settings, always start with a small project before moving on to larger ones.

You can prevent filament bending in your extruder by upgrading your 3D printer to an all-metal extruder. If you want to upgrade your extruder from Thingiverse, this is a more convenient solution.

Direct drive systems are another popular upgrade for extruders. Since Bowden tubes have been eliminated from the Ender 3, the Ender 3 (Pro) can print flexible filaments such as TPU much more precisely. Printing 3D models with flexible materials has a higher chance of success because the filament paths are shorter and the traction is greater. A higher temperature can also be achieved by eliminating the PTFE tubing and using an all-metal hot end.

Conclusion

Flexible filaments have become very popular mainly due to their rubber-like properties and appearance. When printing TPU 3D filament, it is important to take the time to allow the 3D printer to print slowly. You may also need additional tape or Dimafix spray to ensure good adhesion of the filament to the surface. A special PEI straightener has also recently arrived on the market which marks a revolution among straighteners. The filament adheres perfectly to the PEI plate, but when the product cools down, you can remove it easily without any tools.

If you want to start printing flexible filament with 85A hardness and are wondering which 3D printer has a direct drive extruder, is great for home or small business use, we recommend you take a look at Creality Ender.