A new manufacturing process for shoes that requires no stitching, no lasting and no assembly, called 3D bonding, is going to be adopted by a Portuguese manufacturer of safety shoes, AMF, and by Keen Footwear in the U.S. for its outdoor shoes. The process takes only a few seconds and can be applied to all kinds of shoes in any natural or synthetic materials, including microfibers, Cordura and even metal.

The presentation by AMF of this new process was one of the highlights of the successful UITIC convention held in Portugal last month. The process, which is covered by 14 pending patents, uses only an injection machine and an injection mold which, in the case of AMF, are being supplied by Desma and Fagus.

The various pieces of leather or other materials that make up the shoe are placed in a three-dimensional mold that has cavities for their positioning. A three-dimensional countermold is then introduced to press each piece against the mold. It has an entry point for a network of channels that pass between the pieces of the puzzle to inject a liquid material.

This liquid, which is supplied by Huntsman Polyurethanes in the case of AMF, changes to a solid state when it is inside the mold, permitting the connection among the pieces to generate the final product. The polymer has the function of a skeleton that holds the pieces together permanently.

The 3D bonding system requires less labor and energy than conventional processes, and it doesn't require glues and other chemicals that can be a health hazards. It uses less material because the pieces are bonded together rather than overlapped or stitched. Thus, like 3D printing, the technology can be installed anywhere, closer to the market.

Aside from the resulting cost reduction, particularly if the process is automated, the technology can be combined with 3D modelling to allow countless customization opportunities and the production of small batches. It also eliminates friction points for the foot, and according to AMF, it improves shock absorption and the rebound.

AMF, which plans to start using it as of next year, will have exclusive rights for its application over the next three years to safety shoes marketed in Europe, using a new factory in Guimarães; The €10 million investment will allow it at least double its current production of between 1,500 and 1,700 pairs per days.

Using original colors and designs, the Portuguese company has been able to triple its production in the last five years, partly by using an injection molding machine supplied by Desma since 2015.

Described as a new universal manufacturing method that can also be applied to handbags, apparel, furniture and other products, the 3D bonding technology has been developed by Simplicityworks, a Spanish company based in Elche, Spain. The inventor and head of the company, Adrián Hernández, who is being aided by a business angel in the U.S. for this project, is discussing its application with some other important footwear brands.