ATOM Lab, the research unit of cobbling machines maker ATOM, will show an automated process for shoe production for the first time at the Simac Tanning Tech trade fair in Milan from February 20–22, 2018. At its booth in Hall 14, visitors can select 3D-printed soles and uppers, and have customised shoes made for them.

The most technically challenging step in this process is bonding the outsole to the shoe upper. Plastics company Covestro has made an efficient solution based on polyurethane raw materials for adhesives, which are applied to the outsole or upper by means of digital printing.

ATOM Lab used a variation of the melt layer method, Fused Deposition Modelling, using strands of melt-processable adhesives – the filaments – which are melted. The molten adhesive is applied according to a digital print layout. The sole and upper are then joined under pressure. This creates a solid, permanent adhesive bond.

This application using adhesive filaments is quick and efficient. Furthermore, it is very precise and reproducible, and it is also well suited for absorbent substrates. Due to the use of solid filaments, for example, the subsequent drying process may be dispensed. The adhesive features a high initial strength. Since application takes place from the melt, the adhesive is already activated. If the open time is sufficiently long, the fabricator can dispense with prior heat activation.

Polyurethane adhesives have proven to be successful in shoe manufacturing. They are easy to process and result in flexible yet strong and durable adhesive joints with high impact resistance. Covestro offers a comprehensive range of raw materials for one- and two-component adhesives that are often developed in close collaboration with formulators.

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Photo 1: Covestro´s digital print experts Dr. Jörg Tillack (right) and Lukas Breuers examine a shoe sole with an adhesive printed on it. In the background you can see a printer for fused filament fabrication (FFF).

https://www.britishplastics.co.uk/News/covestro-enables-shoe-innovator-to-3d-print-on-demand-shoes-/