German chemical company Covestro has revealed the first details about a new application for its TPU material for additive manufacturing: 3D printed orthopedic insoles for shoes. The company will be showcasing a prototype of the customizable insoles at the upcoming K 2019 plastics trade fair in Düsseldorf.
Orthopedic insoles, also known as orthotics, have presented an interesting opportunity for the additive manufacturing industry. Traditionally, the custom products were made by hand and required extensive time and resources to produce. For the wearer, they could cost several hundreds of dollars to purchase. With its mass customization potential thanks to accompanying technologies like 3D scanning, however, 3D printing has proven to be a viable solution for manufacturing custom insoles at faster and cheaper rates.
In Covestro’s case, its orthopedic insoles are produced using an automated, fully digitalized process. Because of the digital supply chain in place—which allows for a 3D file to be sent to a 3D printer almost anywhere in the world—and because of additive manufacturing’s nature, the production process for the insoles generates nearly no waste and is highly scalable.
The material used to produce the insoles is Covestro’s TPU for 3D printing, a thermoplastic materials with tunable flexibility and hardness.
“Thermoplastic polyurethane is the material of choice for this application thanks to its favorable range of properties,” explained Patrick Rosso, Head of Additive Manufacturing at Covestro. “In particular, our TPU products cover a wide range of hardness. The hardness can also be adjusted by changing the printing structure. This allows manufacturers to print shoe insoles that are completely custom-made—with hard or soft contact areas.”
Covestro is not working alone on its insole initiative: it has partnered with an unnamed company to test various sole designs to determine which are the easiest to print and the most durable. Early tests have showed promising results on both fronts.
In addition to being most efficient to produce, 3D printed insoles can also be more comfortable than traditional ones. That is, many conventional insoles are made by forming or machining rigid foam blocks which have limited breathability. With 3D printing, however, porous structures could be designed to improve breathability and comfort.
This isn’t the first time Covestro has dipped its toe into the footwear market. In 2018, the company presented a design for a manufacturing solution for orthopedic shoes at the OT World Orthopedics fair. The process allowed for dramatic reductions in production time (from weeks to mere days) and grabbed the attention of attendees. At the time, customers apparently floated the idea of using the same technology to 3D print insoles, which inspired Covestro to pursue the current project.