Analysis of the influence of 2D weft knitting process parameters on fabric characteristics for sport shoe uppers

Sport shoes consist of two main elements, the sole and the upper. The upper typically consists of several pieces that are combined in a time and cost intensive production chain. Each of these individual pieces fulfils a necessary requirement for the sport shoe. A recent trend is the production of uppers using the weft knitting technology. A huge advantage of weft knitting compared to the other fabric production processes for shoe uppers is the integration of all necessary shoe functions (e. g. stability, air permeability, cushioning) in one fabric piece within one production step. Currently produced weft knitted shoe uppers use the flat knitting technology which offers high flexibility regarding its structure options but is very slow in production, taking about 45 minutes to produce the two uppers for one pair of shoes. The aim of the thesis is the development of a knitted shoe upper with different functional zones for lightweight running application using the small circular knitting technology. Compared to the current knitted shoe uppers, the new shoe upper possesses better properties regarding the economic manufacturing by reducing the production time to one third while offering similar mechanical properties. The advantage of the high adjustability of weft knitted structures leads to the disadvantage of difficult and time-consuming product developments. The resulting fabric characteristics are influenced by various machine parameters which need multiple iterations of adjustment and the know-how of well trained technicians. To compensate this disadvantage, the new ‘Textile Development Method – TED’ can ease the development process by providing a guideline for the systematic realization of new product ideas. Integrated correlation matrixes are used to predict the resulting product properties and with this allowing developers to accelerate the market entry of new products. Using the small circular knitting technology and the TED method, a competitive new lightweight running shoe upper prototype with multiple function zones was realized within the first iteration cycle. The desired mechanical properties could all be fulfilled and the production process is faster compared to the flat knitting technology.