3D printing takes a new turn
A new generation of 3D printers can apply decoration or performance features directly onto fabric. Components made using additive manufacturing are also finding novel functional uses in shoes and backpacks. Together they may signal a new dawn for a technology that has yet to find a viable industrial use case, otherwise known as ‘killer app’, in consumer goods.
Additive manufacturing found its first uses in prototyping. The development of desktop 3D printers then fuelled a boom which in a short time seemed to go bust. In fashion, the technology inspired a number of avant-garde designers, who include Iris Van Herpen and Julia Koerner. With the introduction of printers that can apply three dimensional shapes and details directly onto a textile base, a whole new field of ornamental or functional features is now possible.
Stratasys’ new J850 TechStyle printer, introduced last year, breaks away from the mould that made first-generation 3D-printed and plastic-structured dresses mostly unwearable. No small feat to develop, the company based in Eden Prairie, Minnesota, and Rehovot, Israel, dedicated nearly eight years to making it work. Its uptake has been much faster and it is now being used to make elements for tens of thousands of products, Joana De Medina, Stratasys fashion account manager for France, tells WSA.
The shift from making a standalone 3D-printed element to applying a plastic polymer directly onto fabric posed a number of engineering challenges to the company’s R&D teams. The first of these was finding a method of fixing the resin on different types of textiles, whether flat and smooth or with open mesh structures. This stage of research led to the creation of a specific process to make the first layer of resin penetrate the textile to form a structural, mechanical bond that allows the three-dimensional forms to adhere to an item of clothing and withstand washing.
Stratasys’ TechStyle device ‘prints’ a photosensitive acrylic resin that is polymerised by light using two ultraviolet (UV) curing lamps that surround the printer head. This is different from fused filament fabrication, which deposits a polymer through a heated printer extruder head. “With our technology, there is no need to wait for a fabric to cool after printing,” says Ms De Medina. The printer deposits the resin in layers measuring 27 microns, each one is cured, or solidified, before the printer head deposits another layer and gradually builds up a shape, as in any additive manufacturing process. Stratasys has developed two types of resins, a flexible and a rigid one, that can be blended to obtain different effects.
Like any digital printer, the device is equipped with cartridges that include the traditional four CMYK colours, an opaque white, a clear resin, and a cartridge containing the first fixing layer. Combinations of these are said to be able to make 600,000 different shades. “The material cabinet holds two sets of eight cartridges. This makes it possible to swap empty cartridges without interrupting printing and speeds up productivity,” says Ms De Medina.
The substrate, which can be a textile or leather, undergoes a pre-treatment process before printing and cannot have any hydrophobic or water repellent finish. Its size cannot exceed 2m x 2m and its thickness needs to be in a range of 0.1 to 3mm. The panel is placed on a tray, and held flat by a magnetic system. Each printer has two trays, so an operator can prepare one tray while the other is being printed, another feature designed to speed up processing. When printing smaller panels, such as shoe uppers, they are placed on a support material, adding a manual operation to the process.
The main design constraint is the size of the printed pattern which is limited to 36 cm x 46 cm (14 inch x 18 inches). “The TechStyle printer was made using an existing chassis,” says Ms De Medina, suggesting that if a market for larger 3D-printed surfaces is identified, the company could develop a larger model.
The design stage is fully digital, using software to create the pattern and estimate production times. In addition to the size of the tray and the printing surface, another design constraint is the compatibility between the 3D-printed shape and the structure of the substrate. Long spiky shapes will not hold if their base is too small, but she says designers can play with height and base to overcome these challenges.
Not only decors
Ms De Medina insists that the TechStyle 3D-printer is not only designed to print a decor or update beading but it can also add a function. Among these, she says that thermal or pressure sensors have been printed by designers. “We are just beginning to explore the possibilities of the technology and we are open to collaborations,” she says.
When digital printing specialist Kornit, a company also headquartered in Israel, acquired Massachusetts-based Voxel8 in 2021, it made its first steps into direct-to-textile 3D printing. “The technology we acquired with Voxel8 includes synthetic elastomers that can be produced with different firmness, for a range of decorative and functional purposes such as grip, bracing, cushioning, impact resistance and waterproofing. These materials can be applied to a range of substrates, both natural and synthetic,” Robert Zoch, global content manager for Kornit Digital, tells WSA.
In addition to Voxel8’s technology, Kornit’s XDi printers can make what it calls “threadless embroidery” and ‘flat’ or micro three-dimensional decors in an array of materials including silicone, metallic, reflective or high-density substances. The company is planning to launch a new 3D printer, the Kornit Apollo, that can apply its XDi technology to ready-made garments. “It will be the first system for sustainable, single-step, on-demand digital direct-to-garment production with integrated curing capable of delivering 400 retail-ready applications per hour,” he says. Much like the company’s legacy digital textile printers, the 3D printers allow on-demand and waste-free production. Their versatility makes it possible to “localise production to mitigate supply chain risk and fulfil orders faster, in any quantity,” says Mr Zoch.
Confident in the potential of its digital and 3D printers, Kornit hopes to achieve revenues of $1 billion by 2026. Its sales in 2021 were $322 million and it expects to close 2022 with revenues of $281 million. Stratasys does not operate in the same market, but for comparison’s sake, its sales in 2021 amounted to $607.2 million, up 16.6% compared with 2020. The company derives two-thirds of its revenues from sales of products and consumables and roughly a third from services (including spare parts, maintenance).
Support & cushioning
California-based Carbon 3D is another maker of 3D printers that has gained a foothold, literally, in the sports industry as the supplier of the machines that make the 3D printed soles of adidas’ Futurecraft 4DFWD shoes. Its Digital Light Synthesis technology polymerises a resin using light, as does Stratasys’s TechStyle printer. The sophisticated lattice-like structures it can manufacture have found many applications in sports equipment, including bike saddles and helmets. Two German companies, Zellerfeld, based in Hamburg, and Oechsler, based in Ansbach, near Nuremberg, have acquired Carbon printers and have worked with designers and brands from Heron Preston to Dior and from Rains to Botter, to develop outlandish footwear.
Carbon’s printers have also caught the eye of backpack makers, who have tested its potential for one-off trials as well as commercial product ranges. The cushioning and energy-returning properties of the three-dimensional back modules made by Carbon’s 3D printers is what struck Magdalen Hamel when she first discovered the components that now equip Jack Wolfskin’s Aerorise range of packs. The category manager for equipment at the German brand describes it as an ‘aha’ moment. “The initial aha moment was not visual, but tactile,” she says. “When I touched the module, it squeezed, I could feel the energy absorbed and returned. It felt very cool,” she tells WSA.
She immediately identified the benefits it could provide for hikers: “It felt like it could be a good solution to offer a user a supportive, ergonomic fit, provide ventilation and remain very lightweight. It is a potential game-changer for backpacks.” After a soft launch last fall, the brand is rolling out three Aerorise backpacks for summer 2023 in three sizes (20, 30 and 40 litres), and each has four 3D printed pads developed in a collaboration involving Jack Wolfskin, Oechsler and Carbon 3D.
The pads are made from an elastomeric polyurethane that can have varying levels of firmness, for structure, or softness, for comfort. “This is a key difference compared to conventional backpacks where foams of different densities need to be combined with an air mesh to achieve the necessary support and breathability,” she says. The highly breathable structure of the pads is said to reduce back temperatures by up to 5°C. “When the load and the dynamics of body movement come together, the pads create a pump effect. There is an intake of air and then it is pushed out. These are the extraordinary properties of the concept and material,” says Ms Hamel.
On-demand & zero waste
3D printing is an on-demand and no-waste process that makes it possible to streamline manufacturing and limit the unnecessary impacts of unused or excess material. But it takes eight hours to print a pad. “It is expensive, and it is worth every penny,” she says. “A user immediately feels the difference. That is our key message, and our key feedback. Testers have told us that ‘the load flies off the back’ and ‘you forget you are wearing a backpack’.”
Earlier last year, Vaude showcased a backpack with 3D-printed components, the Novum 3D, also made by Oechlser on Carbon 3D printers. This prototype was part of the German sportswear brand’s investigation into monomaterial designs, Benedikt Tröster, company spokesperson tells WSA. The pads, pack sac and straps were made from a 100% thermoplastic (TPU) material and the non-TPU components can easily be removed because of a fully welded, instead of sewn, construction, he adds.
In 2022, US-based pack maker Osprey introduced a similar concept with its UNLTD Airscape and Antigravity packs. They are outfitted with 3D-printed pads, also made on Carbon printers, assembled on a ripstop shell fabric made from a high-tenacity UHMWPE fibre, similar to Dyneema. The lumbar pads feature three levels of cushioning, from firm to soft. The range initially programmed for a commercial launch in the fall of 2022 was delayed to this spring.
A sustainable 4.0 technology
The makers of 3D printers readily put forward the sustainable characteristics of their machines that produce sophisticated structures on demand and with little-to-no waste. Last year, Carbon introduced a new partially biobased resin, EPU44, which is 40% derived from plants and offers the same performance properties, it states. Adidas is already using this new greener polymer to make sneaker midsoles. Stratasys points out that its resin is not a thermoplastic and can therefore be recycled. Kornit adds to these features the fact that you print only what you want to print, which makes it possible to relocate production closer to consumer markets. This is a point that Jack Wolfskin also appreciates, since its 3D printing partner is also based in Germany.
A bona fide Industry 4.0 technology delivering custom aesthetics or properties, 3D printing is returning to the forefront as a new manufacturing technique for apparel and accessories. Its ability to combine form and function in new ways may signal a new phase in the evolution of design.
German activewear brand adidas launched its first Futurecraft shoes with 3D printed soles by Carbon in 2015. Its newest 4DFWD running shoes have a bowtie-shaped lattice midsole that is said to convert vertical pressure into a horizontal force, providing runners with a smooth forward transition.
CREDIT: Adidas
