4.2.2. Stabilization of Coils

Complex coil constructions have to be inherently stable for several reasons: stability facilitates logistics (e.g., transport of preformed coils from the winding machine to assembly in the housing) and contributes to protecting the sensitive materials in the pads from damage. It simplifies the positioning of components and helps to maintain even complex shapes such as correctly distributed winding distances or to reduce process time. Depending on how the coils are possibly fixed in the pad, e.g., with full encapsulation, they may only have to be self-stable for a short period of time.

There are various options for coil carrier materials and fastening methods that can be divided or combined into mechanical (sewn on textile, staples, base plates with hooks or grooves, rigid coil formers) and adhesive (liquid or sprayed adhesives, adhesive foils, or self-adhesive cables). Various concepts were tested for this purpose. Base plates with grooves enable the high-precision placement of the winding ends. The combination of this plate and a laying tool with, for example, a tool for feeding adhesive strips also enables accurate placement and fixation of the winding. Another tested system includes a vacuum gripper that grips self-adhesive strands and places them on a flat plate. By adding a heat source (hot air or laser), the cables can be fixed directly to the areas that are important for the shape.
