3D printing of functional anatomical insoles

Abstract Anatomical insoles and additions have a corrective action on the footwear user. They are intended to reduce and adequately distribute plantar pressure among support points, thus minimising the stress these points can undergo. Such customised components have traditionally been manufactured either handcrafted or by subtractive techniques, i.e. by milling a sheet of material. Latest advances in additive manufacturing (AM) techniques and, in particular, the popularisation of 3D printing by fused deposition modelling (FDM), have opened new ways for the production of anatomical insoles. These technologies allow additional functionalities to be added, as for instance the use of materials with antimicrobial properties, or, at a structural level, zonal control in 3D design to increase cushioning capacity. The latter cannot be achieved by traditional manufacturing techniques, in that the inside of the element is not accessible. However, there are no CAD tools available for the design and production of insoles, which are specifically oriented to take advantage of the benefits that AM can bring about. Based on a previous study about the possibilities for functionalisation of anatomical insole materials and structures, this paper intends to review certain CAD methodologies for the design and manufacture of insoles by means of additive manufacturing techniques. These techniques will be employed to design and produce prototypes through which it is possible to assess such techniques. In order to study the feasibility of using this technology for the manufacture of customised insoles in a real production environment, this paper presents a comparative analysis of the proposed technology and the technology that is currently being used.