Warp knitting

Warp knitting is a family of knitting methods in which the yarn zigzags along the length of the fabric, i.e., following adjacent columns ("wales") of knitting, rather than a single row ("course"). For comparison, knitting across the width of the fabric is called weft knitting.

Since warp knitting requires that the number of separate strands of yarn ("ends") equals the number of stitches in a row, warp knitting is almost always done by machine, not by hand.

Basic pattern of warp knitting. Parallel yarns zigzag lengthwise along the fabric, each loop securing a loop of an adjacent strand from the previous row.

Types

Warp knitting comprises several types of knitted fabrics. All warp-knit fabrics are resistant to runs and relatively easy to sew. Raschel lace—the most common type of machine made lace—is a warp knit fabric but using many more guide-bars (12+) than the usual machines which mostly have three or four bars.

Tricot

Tricot is very common in lingerie. The right side of the fabric has fine lengthwise ribs while the reverse has crosswise ribs.[1] The properties of these fabrics include having a soft and 'drapey' texture with some lengthwise stretch and almost no crosswise stretch.[1]

Milanese knit

Milanese is stronger, more stable, smoother and more expensive than tricot and, hence, is used in better lingerie. These knit fabrics are made from two sets of yarn knitted diagonally, which results in the face fabric having a fine vertical rib and the reverse having a diagonal structure, and results in these fabrics being lightweight, smooth, and run-resistant.[1] Milanese is now virtually obsolete.

Raschel knit

Raschel knits do not stretch significantly and are often bulky; consequently, they are often used as an unlined material for coats, jackets, straight skirts and dresses. These fabrics can be made out of conventional or novelty yarns which allows for interesting textures and designs to be created.[1] The qualities of these fabrics range from "dense and compact to open and lofty [and] can be either stable or stretchy, and single-faced or reversible.[1] The largest outlet for the Raschel Warp Knitting Machine is for lace fabric and trimmings. Raschel knitting is also used in outdoors and military fabrics for products such as backpacks. It is used to provide a ventilated mesh next to the user's body (covering padding) or mesh pockets and pouches to facilitate visibility of the contents (MIL-C-8061).

In 1855 Redgate combined the principles of a circular loom with those of warp knit. A German firm used this machine to produce "Raschel" shawls, named after the French actress Élisabeth Félice Rachel. In 1859 Wilhelm Barfuss improved the machine to create the Raschel machines.[2] The Jacquard apparatus was adapted to it in the 1870s. The Raschel machine could work at higher speeds than the Leavers machine and proved the most adaptable to the new synthetic fibres, such as nylon and polyester, in the 1950s. Most contemporary machine-made lace is made on Raschel machines.[3]

Stitch-Bonding

Needle shift

Needle shift technique is when “Both outer warp layers [are] secured in one procedure by incorporating a shift of the needle bar during the stitching process, creating endless possibilities for the arrangement and patterns in the stitch-bonding process.[4]

Advantages

Producing textiles through the warp knitting process has the following advantages[8]

Applications

Warp knitted fabrics have several industrial uses, including producing mosquito netting, tulle fabrics, sports wear, shoe fabric, fabrics for printing and advertising, coating substrates and laminating backgrounds.[9]

Research is also being conducted into the use of warp knitted fabrics for industrial applications (for example, to reinforce concrete), and for the production of biotextiles.

Warp knitting and biotextiles

The warp knitting process is also being used to create biotextiles. For example, a warp knitted polyester cardiac support device has been created to attempt to limit the growth of diseased hearts by being installed tightly around the diseased heart. Current research on animals “have confirmed that...the implantation of the device reverses the disease state, which makes this an alternative innovative therapy for patients who have side effects from traditional drug regimes”.[10]

References

  1. 1 2 3 4 5 Sarah Veblen, "Samplings of Weft and Warp Knit Fabrics", Threads Issue #97, 2012
  2. ↑ Silva, Marcos (2008). MALHARIA - BASES DE FUNDAMENTAÇÃO. Universidade Federal do Rio Grande do Norte. p. 2. Retrieved 22 December 2014.
  3. ↑ Jeremy Farrell (2007). "Identifying Handmade and Machine Lace" (PDF). DATS (Dress and Textile Specialists) in partnership with the V&A.
  4. 1 2 3 4 J.Hausding and C.Cherif, "Improvements in the warp-knitting process and new patterning techniques for stitch-bonded textiles", Journal of the Textile Institute, 2012
  5. 1 2 3 4 5 Hausding, Jan, Lorenz, Enrico, Oretlepp, Regine, Lundahl, Anna. Application of stitch-bonded multi-plies made by using the extended warp knitting process: reinforcements with symmetrical layer arrangement for concrete. Journal of the Textile Institute, 2011, p. 1.
  6. 1 2 Gokarneshan, N., Varadarajan, B., Sentil kumar, CB., Balamurugan, K. and Rachel, A. Engineering knits for versatile technical applications: Some insights on recent researches. Journal of the Textile Institute, 2011, p. 68.
  7. ↑ Hausding, J. Widulle, C., Paul, C., Cherif, C., "Manufacturing method for symmetric laminates for improves stitch bonded multi-plies"], 13th European Conference on Composite Materials", June 2008
  8. ↑ Kiron, M.M.I, http://textilelearner.blogspot.ca/2011/05/defination-and-properties-of-warp_8342.html, "Introduction of Warp Knitting|Principle of Warp Knitting|Properties of Warp Knitted Structures",
  9. ↑ http://www.warpknitting4u.com/, 2011
  10. ↑ R.D. Sumanasinghe and M.W. King, "New Trends in Biotextiles-The Challenge of Tissue Engineering", The Journal of Textile and Apparel, Technology and Management, 2003

Shaeffer, C. (1994) Claire Shaeffer's Fabric Sewing Guide, updated ed., Chilton Book Co. ISBN 0-8019-7802-5

External links

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