A large part of 3D prints are rigid models that must adhere to specified dimensions. This is important for 1:1 scale prototypes, for example, but also for various types of enclosures or parts of mechanical systems that must conform to the other elements of the system. In some cases, however, designers do not need a filament that is rigid and resistant to bending, but on the contrary – a flexible one that deforms and returns to its original shape. For such prints, TPU filaments are invaluable; we present them in more detail in our article.
TPU as a plastic
Thermoplastic polyurethane (TPU for short) has many industrial applications. Microscopically, this flexible material consists of two types of structures: long, deformation-prone “soft” chains and shorter, highly polarized “hard” chains. They actually form a crystal structure. However, if you heat the TPU, the crystalline “network” changes its properties and polyurethane can be formed very easily. Thanks to this, the material is used in the automotive industry, in the production of sports accessories, tools, medical equipment or in glass lamination. The use of TPU film makes glass and mirrors more resistant to cracking. Polyurethane is something we encounter in everyday life as it is one of the most popular raw materials used in the production… of cell phone cases. The “rubber” cases we put smartphones in are mostly made of TPU.
Main features of TPU filaments
Thermoplastic polyurethane, used as a consumable material for 3D printers, allows designers to create flexible elements of mechanical systems and dimensionally stable structures. TPU filaments are similar to rubber: they guarantee high flexibility, which means that all parts printed with TPU easily return to their original shape after being compressed. Models made of TPU filaments are abrasion resistant and have a high resistance in contact with many chemicals – especially oils and greases. They can withstand changing weather conditions very well. Models made of thermoplastic polyurethane do not deteriorate with impact. They also have the ability to absorb vibrations and shocks (which makes TPU filaments even more similar to rubber).
3D printing with TPU
If you decide to print with TPU filaments, there are a few basic things to consider. The first is to choose the right 3D printer – it must be suitable for this type of material. Most amateur or semi-professional printing devices are equipped with Bowden extruders, meaning they have a tube that guides the plastic filament. Unfortunately, in this case, the TPU filament may present too much resistance when trying to move it through the teflon tube, so that the filament cannot be continuously fed to the nozzle. It is therefore necessary to check whether a particular 3D printer model allows the use of flexible polyurethane.
The functionality of the device itself must go hand in hand with the experience of the operator. Much depends on the printing parameters set. For TPU filaments, it is usually necessary to heat the nozzle to a temperature of 210-240°C and the work table to about 20-80°C. Exact values sometimes have to be determined experimentally. Another requirement is to set a lower 3D printing speed – it takes longer to create a model from TPU filaments. If the printing speed is too high, there is a risk that the nozzle will “pick up” the previously applied layer.
A well-planned process will certainly “pay off” – you will get a solidly manufactured model with perfectly adhering layers.
Filaments for 3D printing
Summing up
TPU filaments are a dream come true for many designers. Thanks to the use of this plastic, they can create precision-fit details from a rubbery material. This way, they can easily get the necessary seals, tires, bumpers or covers, and even flexible housing elements. TPU filaments for 3D printers require a lot of skill in choosing parameters (such as temperature or printing speed) and often careful testing of different variants. If the printer is adapted to work with TPU filaments and the operator can plan the process, enormous possibilities open up for the designer.
