All major sports apparel brands are researching the possibility of printing high-performance footwear and are supported by material and printing equipment manufacturers.
Adidas and the United States 3D printing company Carbon established a strategic partnership to jointly manufacture Futurecraft 4D high-performance shoes. The German sportswear brand said that it uses 17 years of operating data to design a new midsole, and uses digital footwear manufacturing processes. , Eliminating the need for traditional prototyping or molding.
Carbon's Digital Light Synthesis (DLS) process uses digital light projection, oxygen-permeable optics, and liquid resins to create high-performance, durable polymer products.
Performance parameters
Adidas library runtime data was used to incorporate functional considerations into the midsole design. The use of these data allowed Adidas to design a midsole with both athletic, cushioning, stability and comfort performance.
Compared to standard 3D printing manufacturing methods, DLS technology is said to solve problems such as low production speed and scale, poor surface quality, and color and material limitations.
The midsole is made of liquid, adidas said, forming a grid of 20,000 individual support points that optimize energy return.
Nike now also began to print uppers. Eluid Kipchoke won a victory in the Vikings London Marathon in 2018 with a pair of 3D-printed TPU sneakers. The company claims that this is the first time that high-performance footwear has been made in this way.
The way to victory
The upper is made using solid deposition modeling. In this method, the filaments are unwound from the coil, melted, and then layered. Nike says that printing technology can make prototypes 16 times faster than other manufacturing processes.
The company also uses this technology to incorporate athlete-specific data into textile geometry. Nike uses data obtained from athletes and analyzes these data to confirm the ideal composition of the material. This analysis will be used to design textiles.
The company claims that 3D printed textiles are more dynamic than traditional woven fabrics. This is because the warp and weft threads are intertwined.
The company stated that the advantages of 'Flyprint's textiles are reflected in the blending characteristics of the materials. In knitted or woven textiles, there is a frictional resistance between the interwoven weft yarns and the weft yarns. In print textiles, it is more possible to achieve precise coordinated control. . '
It also added that 3D printed textiles are 'lighter and more breathable' than earlier fabrics.
Rapid development
The Zoom Vaporfly Elite Flyprint on Kipchoge's feet was designed based on his feedback on the shoes he wore at the 2017 Berlin Marathon. The shoes he wore in the London Marathon in 2018 were 11 grams lighter than the first time.
The Reebok liquid factory process was launched in 2016, using software and robotics to draw shoes in three dimensions. The liquid polyurethane materials that BASF manufactures for Reebok are used to accurately chart parts of shoes in three-dimensional planes.
The liquid flow shoe made from this polyurethane system can be used to make outsole directly, instead of making the sole out of the mold alone. Once absorbed, the material will begin to solidify. The side of the big bottom is surrounded by 'wings', providing the entire foot with More customized fit and better support.
Improve performance
New Balance and Formlabs, a 3D printing specialist in Boston, also signed an agreement in 2017 to implement larger-scale 3D printing. The two companies are developing footwear-specific materials and printers to create products that enhance athlete performance. Curing Print Form 2 powers the printing process.
This is not the first time that New Balance has been involved in 3D printing: As early as 2013, Jack Bolas became the first track and field athlete to wear spiked shoes made with custom 3D printing technology. To complete the design, New Balance uses a force plate, inside the shoe. Sensors and motion capture systems to simulate events to obtain individual biomechanical data.
This initial 3D printing project led to the subsequent further study of custom printing of soft parts required for the midsole. New Balance launched Zante Generate in 2016 and called this the first full-length 3D printed midsole. It uses DuraForm TPU in 3D system. Elastomeric laser-sintered powders are used in a selective laser sintering process to fabricate the midsole layer by layer. The resulting product is a midsole with a complex honeycomb structure. New Balance claims flexibility, strength, weight and durability. Get 'best balance'.
Bonded together
3D printed soles and uppers must still be glued together. According to Atom Lab, the most challenging step encountered by the shoemaker Atom’s R&D unit in the technical field is to bond the outsole to the upper. The company has collaborated with Covestro to develop a process that applies adhesive polyurethane raw materials to soles or uppers through digital printing.
Atom uses a variant of the fuse-making hot-melt layer technology to apply an adhesive. The melt-processable adhesive filaments are first melted and the molten adhesive is applied according to a digital print layout, followed by applying pressure to connect the sole to the On the upper, it creates a firm and permanent adhesive bond between the two.
According to Atom, this application of adhesive filaments is fast and efficient. Accurate and reproducible, suitable for absorbent bases. Solid filaments are used, so no additional drying process is required.
In addition, the adhesive is applied by the melt and is pre-activated. If the settling time is long enough, there is no need for preheat activation, which saves two processing steps.
Although it is still at an early stage and development is focused on high-end limited edition products, these projects clearly show that the development potential of polyurethane materials may make large-scale implementation of additive manufacturing a reality in the sportswear market.