warp insertion knits

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Fabric Manufacture: introduction to warp insertion knits

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Introduction to Warp Insertion Knits

Knitting Knitting is a method by which thread or yarn may be turned into cloth or other fine crafts. Knitting consists of consecutive loops, called stitches. As each row progresses, a new loop is pulled through an existing loop. The active stitches are held on a needle until another loop can be passed through them. This process eventually results in a final product, often a garment. Knitting may be done by hand or by machine. There exist numerous styles and methods of hand knitting.

Knitting variations To make fabric more interesting knitting machines can be manipulated. By inserting extra warp or extra weft weft yarns, fabric will have an extra set of yarns contributing to aesthetic appeal or tenacity. Inserting warp or weft yarn creates a fabric called knit-weave

Types of Knit WeaveWeft insertion knit:

Warp knitting machines can be adapted with attachments to lay in weft yarns. This may be one weft carried across the knitter or with more complex attachments, a sheet of twenty or more yarns can be used ac filling. Where warp knits may only be knitted with lengthwise stripes or colors variations weft insertion can be can produce crosswise variation as well. The finished fabrics can is more stable across the grain than ordinary warp knit fabric.

Warp insertion knit This technique involves inserting warp yarns into the crosswise knitted structure of the weft knit. The warps are woven in; that is, interlaced on a 1X1 basis with the weft knit yarns. The procedure gives greater dimensional stability in the lengthwise direction.

Insertion warp knitsInsertion of yarns in the warp-knit structure is a relatively simple concept Yarns are laid in the stitches during the knitting process but are not used to form any stitches These laid-in yarns provide dimensional stability and can be in any direction or at angle. Yarns that are not appropriate for knitting can be used such as extremely coarse, fine or irregular etc.

Mechanism of weft insertionWeft insertion can be done by a warp knitting machine with a weft-laying attachment An attachment carries a single filament yarn to and fro across the machine, and this yarn is fed steadily into the needle zone of the machine A firm selvedge is formed on both the sides. More complex attachments supply a sheet of filling yarns to a conveyor that travels to and fro across the machine. A cutting device trims filling yarn tails from the selvedge and a vacuum removes the tails.

Weft insertion warp knitting interlacing

Machine

Principle: Full Width Weft InsertionWhen the needles are in the lowered position during the warp knitting cycle, a so-called 'open shed' effect is created at the back of the machine. It is then possible for a weft yarn, laid across the full width of the machine, to be carried forward by special weft insertion bits over the needle heads and deposited on top of the overlaps on the needles and against the yarn passing down to them from the guide bars. In this way, the inserted weft will become trapped between the overlaps and under laps in the same manner as an inlay yarn when the needles rise but, unlike the latter, the weft will run horizontally across the complete course of loops.

This technique is less restrictive for fancy and irregular yarns than for inlay and, as a weft covers the full fabric width, yarn can be supplied from individual packages. It has the major advantage that weft can be prepared and laid in advance of the timing of the insertion so that it has less effect on the knitting machine speed.The single traversing weft is laid across the back of the machine by a cable-driven carrier that reciprocates on two parallel rods. At the end of the traverse, the selvedge return loop passes around a vertical pin that holds the weft in place until required, whilst the carrier continues its traverse. The weft pins are attached to the needle bar so that the two descend together, releasing the full-width weft at the moment when the weft bits, one above every alternate sinker, advance over the lowered needle heads to insert the weft.

Advantages1)2) 3) 4)

They combine the best properties of both woven and knitted cloth namely, strength, comfort, cove without bulk, and weight. They are lighter weight than double knit but have more covering power. They have the increased crosswise stability of weaves but retain the comfort of the knits. They have characteristics similar to woven fabrics and are much cheaper and available in wide widths.

Disadvantages1. Medium to dark fabric colors are difficult and costly to achieve since the white substrate web and backing layer is visibly perceivable through the weft fill yarns and thus the overall fabric color appears lighter than the actual color of the warp and weft yarns which are utilized. 2. Fashion industry dos not use this interfacing because it does not meet the standard of wearability.

Uses Aircraft and aerospace components

Automotive partsBoat hulls Ballistic protective clothing Structural building components Interlinings of apparel Window treatments Wall coverings

References

Textiles By Kadolph, Kadolph Sara

The Guide to Textiles for Interiors By Dianne R. Jackman, Mary Katherine Dixon, Jill Condra

Thank You

Submitted By: Priyanshu Raj B-Tech(TC) V Sem