On-demand gets directional
A multi-stakeholder team of designers, developers and engineers got together to reconsider 3D-printed sports shoe models, just in time for ITMA.
Among the aisles of exhibits showcasing the latest in textile machinery innovation from 1,709 international suppliers at quadrennial industry trade fair ITMA in June, an intriguing, new 3D-printed athletic shoe concept caught the footwear manufacturing community’s eye. A collaborative effort between French sports retailer Decathlon, US printing technologies developer HP and Italian knitting machinery maker Lonati, the partners’ digital-first, mouldless and glue-free method promises to “reshape” the sustainable footwear landscape, they claim. This will come through improved customisation and repairability, more localised production, faster disassembly and simpler end-of-life recycling.
Stepping forward
Head of footwear for HP’s personalisation and 3D printing business, Barcelona-based Don Albert, tells WSA that work only began on the project earlier this year. He describes his team’s interactions with colleagues from the other two companies as exceptional, citing their “shared commitment to innovation and to pushing the boundaries of technology in the sports industry”. Throughout the development process, weekly calls took place between Decathlon and HP, whose HP Jet Fusion 5200 printer was used to produce the shoe’s midsole and outsole, during which research and development ideas, materials progress and sustainability updates were all discussed and exchanged.
Separately, Lonati’s XT-Machine and Double Cylinder E1530XS systems produced the all-black trainer’s sleek, sock-like upper, made from digitally adjustable, single or double-layer knit fabrics that hug the foot. The knitted sock has an almost animal print surface texture. Together with the HP-printed cushion component, these easily separated parts combine to deliver “unparalleled comfort, lightness, performance and quality”, in the collaborators’ words. Lonati acquired Santoni, the domestic knitting machinery manufacturer responsible for inventing the XT-Machine, back in 1989.
Mr Albert frames HP’s industry-ready 3D printing technology as “a significant step forward” for the sector. In place of more complex assembly, typically involving 12 different materials for sports shoes, each Jet Fusion 5200 printer has the capacity to handle up to three jobs per day, depending on the materials choice. Each job represents ten pairs of trainers. No matter where it is installed, one printer alone makes for a commercially viable operation, he suggests, adding that the pair displayed at ITMA “already holds commercial viability”. In terms of performance, HP is especially focused on developing footwear suitable for runners, he shares. The Reebok and adidas alum further states that certain shoe materials work particularly well with the printers, resulting in what he calls superior cushioning and energy return for athletes, although he does not elaborate on which materials this refers to. On the sustainability side, the on-demand model makes for an intrinsically lower waste and less-energy-consuming production process.
Materials versus machines
“The choice of specific machines and materials in 3D printing is closely intertwined,” Mr Albert explains. Various technical considerations come into play, from temperature range to system compatibility, which inevitably influences materials selection. In turn, end-product performance and functionality ultimately limits designers’ choice of materials, which then feeds into decisions around which machines can be used. For the Decathlon concept trainer, the Jet Fusion 5200’s versatility in printing multiple materials was key, he notes, allowing the sporting goods retailer’s “desired performance requirements” to be met. The series was HP’s very first industrial-grade 3D printer. First released in 2019, it was built for cost-efficient scalability and increased accuracy, repeatability and flexibility at factory level, based on “new systems, data intelligence, software, services and materials innovations”.
The digital technology furthermore enables full footwear customisation, without additional costs. Without the need for a traditional mould, the manufacturer is free to adapt rapidly and tailor each trainer to Decathlon customers’ individual order requirements with precision, according to Mr Albert. This goes beyond colour and design, extending to fit, support and other technical adjustments. From the perspective of Decathlon ‘exploration leader’, Phillipe Seille, “a new era of sustainable and innovative manufacturing” awaits those who follow HP’s 3D printing lead. In terms of materials, the retailer opted for Ultrasint TPU01, a BASF-produced thermoplastic polyurethane (TPU) powder specially designed for HP’s Multi Jet Fusion portfolio, of which the Jet Fusion 5200 printer is a part. The powder is converted into midsoles and outsoles inside the machine.
Recyclability was one of the two main decision-making factors that led to Ultrasint TPU01 making the final cut. The substance has an 80% post-consumer reusability rate, meaning it meshed well with the team’s vision for lower-resource-intensity shoe manufacturing. Second, what Mr Albert calls the material’s “excellent comfort properties” made it “highly suitable” for athletic footwear. Other properties include a Shore A 88 level of hardness. Germany-headquartered BASF has been developing similar concepts since 2010, when it launched its own concept shoe, Pure 1.0, made solely from polyurethane (PU), but incorporating TPU for the laces, inside top layer, chassis, heel cushion, outsole and logo inlays. PU was used for the lower insole, upper and heel. Back then, the significance of the concept, to BASF, was to present customers with an early-stage version of an easier-to-recycle product before they knew they needed it.
A productive relationship
Mr Albert says his team was happy to receive frequent, constructive feedback from Decathlon and Lonati, supplying HP with valuable insights that have already helped tweak its printing systems and processes for the better. The partners are actively working together to ready the Jet Fusion 5200 for larger-scale production, first exploring how to make it eco-friendlier and even more efficient. “This iterative process of collaboration and refinement will ultimately contribute to the development of cutting-edge 3D printing technologies that meet the demands of the sports shoe industry,” he concludes.
The sports shoe manufacturing concept meets Decathlon’s “desired performance requirements” and “already holds commercial viability”.
All Credits: HP!
