TPU filament in 3D printing – use and properties at a glance

TPU filament the all-rounder in 3D printing? Advantages and disadvantages, properties, printer settings and much more – here you'll get an overview of what TPU can do and where the thermoplastic elastomer is used.

What is TPU Filament?

For 3D printing, you can use different printing materials, such as TPU filament. If you want detailed information about this composite plastic, feel free to check out threedom's “What is Filament” post.

When we speak of TPU filament, we mean thermoplastic elastomer; polyurethane that can be formed without chemical changes. TPU translates from English into Thermoplastic PolyUrethane. This plastic is rubbery and therefore elastic. This is an important aspect if you want to print seals and smartphone covers, among other things, with a heatbed (heatable print bed). Responsible for this are the multiphase systems with thermoplastic hard phase and the elastomeric soft phase. To understand all the processes to the result in detail, a physics degree would be appropriate. But with TPU filament, of course, 3D objects can be produced and flexibly formed even without studying physics.

Advantages TPU Filament

The fact that TPU filament is a stretchable plastic goes without saying due to its flexible processing. TPU can be processed without problems between 220° and 250° printing temperature. Still, you should know that the temperature varies somewhat between the offerings of different manufacturers. In addition, there are certain limits in 3D printing that affect TPU processing; these include: the printing speed, the complexity of the printed object (the larger, the more material you need for stability), and the printer type. Probably the most important basis for an optimal printing result is the actual TPU polymer material. As with any product, the same applies here: Quality ensures longevity.

If you want to use TPU filament for your project, you will benefit from its good weather resistance, high UV stability and high tear and abrasion resistance. Even after processing, TPU is resistant to greases and oils as well as some solvents. Whatever color you choose, also enjoy the color fastness of the thermoplastic polyurethane!

Disadvantages – TPU does not come in gold that shines

Like probably every printing material, TPU filament is also afflicted by some disadvantages. However, the disadvantages always depend on the actual processing and the printer's own requirements.

As you can see from the headline, TPU does not come in shiny gold. But still you can choose between the common colors black, white, red and blue. Some manufacturers go one step further and have the filament convince in RAL colors (including yellow, green, bronze). If you do not find what you are looking for, you can have the print material made in your personal color from the RAL palette for an additional charge.

Even though the TPU filament can be processed for versatile 3D printing products, the thermoplastic polyurethane is not food safe.

Another disadvantage is the price of the TPU filament. Unlike PLA, ABS or PETG filament, you have to pay more for TPU. Starting from the basic color white, you should calculate between 20 euros (500 g coil) and 32 euros (1000 g coil). There are also never any limits to the price.

What we must never forget is the environmental impact or sustainability of our 3D products. Even though research has already made great leaps in recent years, the TPU filament cannot convince with this.

Application examples – What can TPU be used for?

TPU filament offers a wide range of applications in 3D printing due to its advantages. This means that different industries benefit from the flexible printing material, which is also hard-wearing and resistant to tensile forces.

TPU is particularly suitable:

  • for three-dimensional seals,
  • for flexible joints and connections,
  • as a damping and cushioning element.

TPU is often processed in the sports industry. The plastic is dermatologically safe and is suitable for the manufacture of fitness wristbands, protectors and seals on fitness equipment, training aids and water equipment. Are you an athlete? Then you know the high demands on sports shoes. TPU is particularly suitable for its production. This is because the plastic withstands water and low temperatures, among other things.

Aerospace engineers have discovered TPU filament for their work. They process instrument panels and sensors made of the thermoplastic elastomer – a good basis for safe aerospace. The automotive industry is taking advantage of the same areas. Vehicles are fitted with levers, sensors and instrument panels with TPU, among other things.

With which settings is TPU printed?

For 3D printing with TPU, some settings should be made. However, these settings are only a general indication, since the quality of the thermoplastic polyurethane plays a decisive role:

  • slow printing speed (between 15 and 20 mm/s)
  • If necessary, increase extrusion factor slightly to ensure optimum bonding of layers and perimeters
  • Disable retract (retraction) on 3D printer to prevent stretching and compression in nozzle

An important prerequisite for printing TPU is the appropriate extruder system that can withstand the maximum temperature of 250°.

What needs to be taken into account when printing TPU?

Before you start with the final printing of TPU, test prints are indispensable. The print material varies from manufacturer to manufacturer, so you should try the appropriate temperature setting for your project. It is helpful to try the test prints from 220° ascending to 250°. Even if a heated print bed (heatbed) is not a prerequisite, its use up to a maximum of 60° can ensure optimum printing results.

Each 3D printing end benefits from the flexibility of the TPU filament. The use of a low Infillis responsible for this. If stiffer objects are involved, increasing the Infillis the right thing to do.

In order to benefit from the best quality of your TPU filament for printing at any time, you should pay attention to water- and moisture-proof storage. Vacuum bags or containers with lids are suitable for this purpose.

Is TPU beginner friendly?

It is difficult to give a blanket answer to the question of beginner-friendliness. After all, no master has fallen from the sky yet, and 3D printing comes with some hurdles for some projects. Nevertheless, it can be said that TPU printing is beginner-friendly if the conditions are right. Thus, it needs the suitable 3D printer that can process TPU filament optimally. In addition, the above-mentioned prerequisites and settings are decisive, as well as knowledge about the processing of TPU. And last but not least: your motivation and some patience to achieve your desired project.

Can TPU be glued?

Yes, TPU can be glued. The plastic is resistant to scratches and cuts. Nevertheless, it has one small drawback. The flexible plastic is difficult to machine, so the use of adhesive is useful for an object result. Gluing works best with cyanoacrylate glue; a transparent super glue.

For bonding, the surfaces to be bonded should be dry and free of dust and grease. They should also be a perfect fit for each other. The adhesive works best when applied thinly. The following applies: the thinner the adhesive film, the stronger the effect.

Is post-processing of TPU filament possible?

The object is printed, but still needs the finishing touches for a uniform-looking surface? With the right technology, tuning is done in a few steps.

We have moved away from machining the TPU surface, instead using our manual and machine grinding capabilities. Grinding can reduce surface roughness and contribute to a pleasant feel. Nevertheless, you should sand with caution; always approach the printed object with “kid gloves”. This is because grinding processes generate heat through friction and, conversely, deformation of the object occurs. Use sandpaper, a Dremel with attachments, and protective clothing such as goggles and a respirator for sanding!

Anyone who works with 3D printers already has a good imagination. Finally, even before printing, the object should clearly “appear before your eyes”. Nevertheless, sometimes things turn out differently than expected and a little color can work wonders. An object with TPU can be staged with paint and varnish. For this purpose, acrylic paint and spray paint are the best variants. For the colored tuning you also need protective clothing with goggles and respirator mask as well as an adhesive spray for plastic parts in addition to paint and varnish.

What is the difference between TPU and TPE?

If you search for information about TPU, you almost automatically come across TPE. TPE is the main category “thermoplastic elastomer”; TPU is a related main group and stands for the thermoplastic polyurethane. Not only the names differ, but also their areas of application in 3D printing.

TPE is mainly used in the automotive and medical industries and is a convincing combination of rubber and plastic. In addition, TPE can be found in the electronics industry, for example as cable sheathing. The sports industry relies, among other things, on yoga mats made of TPE, which are free of PVC and other toxic plasticizers. The rubbery printing material is available in many colors, has a lower hardness and has moderate resistance to chemicals.

TPU, on the other hand, is used for cell phone covers, shoe soles, sporting goods (goggles and fins) and automotive instrument panels, among other applications. The rubbery to hard plastic can have a smooth or rough surface and is a particularly flexible printing material. The color selection of TPU is rather small. TPU has high hardness and abrasion resistance.