Textiles can be used for heating, cooling and lighting. They can measure the heart rate, as well as monitor soil erosion on slopes, and can even be launched into space for use as space reflectors – as long as they are electrically conductive.
The electrical conductivity of warp knitted fabrics is the subject of extensive development work at Karl Mayer. In this project, entitled “textile-circuit”, multibar raschel machines are used with and without jacquard equipment to incorporate conductive yarns directly into the fabric during production. The first results are now available, and show what can be achieved, including the use of fabrics for remote control. The original control tools and production principles were both shown at the IDTechEx Show in Santa Clara and at the Aachen-Dresden-Denkendorf International Textile Conference, both held last November.
Electrically conductive structures with a virtually unlimited range of designs can be produced on multibar raschel machines. This is possible, thanks to multibar patterning using Karl Mayer’s innovative string bar system, with which the yarns can be positioned individually and as required onto a ground – following the principles of tailored fiber placement. The ground can be produced with a wide variety of different designs, and jacquard patterns can also be worked, depending on the type of machine.
In addition to offering extensive design freedom, warp knitting delivers maximum efficiency when producing electrically conductive fabrics. Furthermore, the typical performance features of fabrics, such as softness, flexibility, elasticity and breathability, are fully retained.
At the functional heart of these innovative warp knitted fabrics are filaments containing metal, such as Elitex. According to Sophia Krinner, a textile Product Developer at Karl Mayer, silver-plated nylon can be processed very easily on multibar raschel machines. Her aim in the next few stages is to optimize the sequences on the machine to suit mass production. The textile engineer studied the processing of functional yarns in her master’s degree. Good results were also achieved with the warp knitting of other fine, insulating metal filaments and metallized yarns, such as Shieldex and Agsis. Of course, the flexibility and diameter of the conductive yarns must generally be harmonized to suit the machine gauge and the characteristics of the base fabric.