Whether technical damping elements, flex hoses, handles or keypads, TPU and flexible, rubber-like materials can be used for a wide variety of applications. If the material is processed with the 3D printing technology SLS (or FDM), diverse new possibilities arise.
TPU, also known as thermoplastic polyurethane, is an elastomer plastic that has high flexibility and resistance to greases and oils. In additive manufacturing, TPU has many applications, from shoe soles and tires to custom building components and cell phone covers. It is particularly well suited for 3D printing end products, functional prototypes and design models. In this blog post, you will learn what to consider when 3D printing with TPU, what advantages the flexible material offers in additive manufacturing and in which application areas TPU can show its advantages particularly well. We also provide valuable design tips and weigh up the cost-benefit factor. The focus of this article is on SLS printing technology, since TPU poses great challenges for the printing process and lattice structures made of TPU material cannot be imaged with FDM, for example (support structures, etc.).
In selective laser sintering (SLS), small polymer powder particles are sintered by a high-performance laser. This creates the desired component in a powder bed. In the field of additive manufacturing, SLS enables high productivity at low unit costs - especially in the areas of rapid prototyping, individual production from batch size one and small series. Some special advantages of the material:
You can read the technical properties in detail on the material detail pages:
Selective laser sintering (SLS) and the 3D printing of TPU - an excellent combination, but one that entails some special features. Above all, the special thermal behavior of TPU is relevant. SLS 3D printing with TPU requires adapted process parameters - and process control is challenging. The individual components must be spaced further apart in the build space than when printing PA12, for example. Attention must also be paid to the special features of the material after TPU 3D printing. Cooling the build space cake and de-powdering is more complex in order to be able to release the parts cleanly.
Mechanical smoothing of the surface is not possible with TPU. However, chemical smoothing is possible with specially adapted solvents and work processes. A very interesting option is that the surface can be sealed media-tight. This means that water can no longer seep into the printed component.
If the components are to be colored, this is preferably done by dip dyeing. In this process, the natural color of TPU is overdyed. Another ecological and sustainable property of TPU in SLS 3D printing is that the powder can be 100% reused, since it is not damaged in the thermal printing process. In practice, however, only an admixture of 10 to 15 % per print job takes place in order to keep the quality of the prints constant.
For 3D printing of TPU, comparable design guidelines apply as for the PA12 material. Apart from this, you should take the following special features into account in the design:
For less complex shapes, FDM technology can be an alternative, as it is less expensive for TPU components. However, depending on the geometry, support structures are required for FDM 3D printing. These are required more often with TPU than with other materials, which severely limits the printability of TPU parts with FDM technology. If you have any questions about this, please send an "individual inquiry" to the Store.
Supplemented with lattice structures, highly interesting applications can be realized with TPU. The hardness of the printed components can be very finely adjusted via the geometry. For example, the foam-like Kelvin structure produces soft components with increased resistance to bending loads, while the octet structure, which is also foam-like, enables harder components that optimally withstand tensile loads. Typical applications of TPU from SLS 3D printing include:
When it comes to the question of up to what quantity range TPU can be competitively 3D printed, we have to answer with a rule of thumb. This rule of thumb states that cost-effectiveness is strongly dependent on the size and complexity of the required component. In SLS, typical series have a volume of between 5,000 and 15,000 parts. For TPU, the quantities for economical 3D printing are somewhat lower.
When it comes to very large quantities, TPU 3D printing does not become as cost-effective as injection molding. The relevance of 3D printing of flexible materials such as TPU lies primarily in the complexity - and offers immense advantages whenever production using conventional methods is not possible. Or when small quantities cannot be produced economically using injection molding.
If smaller quantities of a TPU component with simple geometry (without lattice structures and the like) are to be produced, FDM technology is a cheaper alternative.
Image: the bicycle handle could easily be manufactured with FDM technology due to the simpler geometry.
If you have any questions about TPU 3D printing or other specialist topics, please do not hesitate to contact us. We are looking forward to your project.
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