In contrast to standard 3D printing manufacturing methods, the DLS process is claimed to overcome issues such as low production speed and scale, poor surface quality and restrictions in colour and material.
The midsoles are grown from liquid, and Adidas says the lattice network that is formed has 20,000 individual struts that can be adapted to optimise energy return.
Nike has now started printing the uppers, too, and Eluid Kipchoke ran to victory in the 2018 Virgin London Marathon in a pair of shoes with uppers 3D printed out of TPU. The company claims this is the first time the uppers of performance footwear have been created in this way.
The uppers are made using solid deposit modelling. In this method, filament is unwound from a coil, melted, and then laid down in layers. The company claims printing allows prototypes to be created 16 times faster than other production processes.
Nike is also using the technique to incorporate athlete-specific data into the textile geometry. Nike uses data captured from the athlete and this is analysed to confirm the material’s ideal composition. That analysis is used to design the textile.
The company claims that 3D printed fabrics are more dynamic than traditionally woven fabrics. This is because the warp and weft fibres are connected.
‘An advantage of Flyprint textiles comes in the fused nature of the material,’ the company said. ‘In a knit or woven textile there is frictional resistance between the interlaced warp and weft yarns. In a printed textile there is greater potential for precision-tuned containment.’
It added that the 3D printed textile is ‘lighter and more breathable’ than earlier fabrics.
The Zoom Vaporfly Elite Flyprint shoes Kipchoge wore were based on his feedback on the shoes he wore in the 2017 Berlin marathon. His 2018 London marathon shoes were 11g lighter than the first iteration.
Reebok’s Liquid Factory process was introduced in 2016. It uses software and robotics to draw shoes in three dimensions. A liquid urethane material created for Reebok by BASF is used to draw the shoes’ components precisely in three-dimensional layers.
The Liquid Speed shoe is created using this polyurethane system, which is drawn onto the entire shoe as the outsole rather than using a mould to create the outsole separately. As soon as it is drawn on, the material starts to cure and solidify. The outsole has ‘wings’ that wrap around the sides, giving a more custom fit and better support for the whole foot.
New Balance signed a deal in 2017 with its Boston neighbour 3D printing specialist Formlabs to implement 3D printing on a larger scale. The two companies are developing footwear-specific materials and printers that will be able to create products that will improve athlete's performance. Its stereolithography printer Form 2 powers the printing process.