Tufting

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Tufting is an ancient technique for making warm garments, especially mittens. After the knitting is done, short U-shaped loops of extra yarn are introduced through the fabric from the outside so that their ends point inwards (e.g., towards the hand inside the mitten). Usually, the tuft yarns form a regular array of "dots" on the outside, sometimes in a contrasting color (e.g., white on red). On the inside, the tuft yarns may be tied for security, although they need not be. The ends of the tuft yarns are then frayed, so that they will subsequently felt into a dense, insulating layer within the knitted garment.

Tufting is also a technology to reinforce composite structures. A needle twinges through a layered fabric and leaves a loop on the bottom of the structure. It is an economical method to include z-fibre reinforcement that enhances the shear- and de-lamination resistance of the structure. It can handle nearly all shapes and forms and possesses the ability to vary the density of z-fibres (local reinforcement). On the other hand the increase of z-properties is comparably low due to the fact that tufting comprises no force-fit. They are difficult to handle before consolidation and the loops can complicate the consolidation proc-ess. Furthermore the z-fibres do not run straight after consolidation.