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February 2025
Framas is a leading supplier of soles in the footwear industry. They are known to be the partners of the athletic powerhouses. During the Desma House Fair the Framas team was presenting different R&D projects, among those a shoe developed in collaboration with Desma to show the results that can be achieved combining different technologies.
We have met René Medel who is Senior Digital Creation Engineer at Framas for a conversation about the project Framas has presented during the last Desma House Fair.
First of all, can you explain how the shoe has been made?
“This shoe has been developed leveraging the expertise of different partners. We did a collaborative creation process among the group and then in the making: our team in Korea has created the two 3D printed parts using the SLS (*) technology. The first part is a rigid shank that has been co-molded with the TPU outsole and the second part is a heel support, made with a lattice structure, that has been co-molded with the LTPU midsole. For both parts a TPE (**) material (powder for SLS) has been used.
The outsole was made using a traditional TPU injection process at our factory in Vietnam while the midsole was manufactured using the SmartliteO LTPU material from Huntsman. The LTPU is an innovative liquid TPU that can be casted and foamed while maintaining the thermoplastic properties since it does not cure as the traditional PU does. The sole unit was then sent to Desma in Germany for direct soling to the upper using PU.
Overall, the project took almost two months to be completed since – due to its innovative nature – we had to experiment different technical solutions to industrialize the construction. One good example is the construction of the mold needed to keep the 3D printed heel support in the exact position when casting the LTPU. We had to change to geometry of the 3D printed part many times before getting to the final solution of having four pins in the mold connected to the lattice structure of the 3D printed part.”
What was the objective of this project?
“This development moves from the idea that combining the different technologies can open doors to a strep ahead in performances and customization. First of all, we are working to use addictive manufacturing (AM) in real production, not just for prototyping. These parts have been made using SLS technology, but we are also testing resins and extrusion of filaments and pellets. The 3D printed parts are not intended only to save weights in some areas of the sole. They really can add specific properties to the sole. Let’s make an example: the midsole is typically made with a foaming material. Depending on the material we can achieve different results in terms of weight, compression set, rebound etc. But if we add a 3D printed part in the midsole, we can change these performance parameters using not only different 3D printable materials but also designing different geometries. This first project had a 3D insert with the foam all around it, but we can also combine 3d printed shapes with casted foams in different ways: we are testing the 3D print of an entire skeleton and then let the foam penetrate the 3D structure and fill it. The objective is to bring the performances to a different level. It’s the same idea as adding a carbon plate to the midsole. Carbon is another technology that we are testing since carbon plates can also be 3d printed. Depending on the kind of material that you add to the insole you can obtain stiffness or rebound or cushioning.”
Can you give an idea of what is coming next?
“The project had the objective to manufacture a sole unit with the 3D inserts and I can tell that a product like this can be brought to the market because we have fully industrialized the entire process. But we can go further in different directions. Today we can create the entire shoe, as our customers are already doing, offering a combination of traditional manufacturing processes (injection and casting) with 3d printing.
In terms of sustainability, this project presented at the Desma House Fair has a strong impact because the unit even though it has different parts, it is in the reality a mono-material, since the chemical nature of all these materials is similar, and it can be upcycled.
We are also testing other materials such as those of Balena that are bio-compostable materials. These materials today are 3d printable and injectable, but we are also looking at ways to foam them. Maybe combined with injected parts and 3d printed parts that are all compostable. In such a case the objective is to downcycle the unit: bury it and let it compost at the end of the cycle, hopefully in an industrial way.”
Footnote (*) SLS stands for Selective Laser Sintering, a widely used additive manufacturing (3D printing) technique. It involves using a high-powered laser to fuse powdered material layer by layer, creating a solid object.
Footnote (**) TPE is a broader category of materials that behave like rubber but can be processed like plastics while TPU is a specialized type of TPE with superior strength, durability, and chemical resistance.
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