Warp and Weft knitting

  • View

  • Download

Embed Size (px)


Weft vs. Warp KnittingWeft Warp

Weft knitting. Weft knitting uses one continuous yarn to form courses, or rows of loops, across a fabric. There are three fundamental stitches in weft knitting: plain-knit, purl and rib. On a machine, the individual yarn is fed to one or more needles at a time. Weft knitting machines can produce both flat and circular fabric. Circular machines produce mainly yardage but may also produce sweater bodies, pantyhose and socks. Flatbed machines knit full garments and operate at much slower speeds. The simplest, most common filling knit fabric is single jersey. Double knits are made on machines with two sets of needles. All hosiery is produced as a filling knit process. Warp Knitting. Warp knitting represents the fastest method of producing fabric from yarns. Warp knitting differs from weft knitting in that each needle loops its own thread. The needles produce parallel rows of loops simultaneously that are interlocked in a zigzag pattern. Fabric is produced in sheet or flat form using one or more sets of warp yarns. The yarns are fed from warp beams to a row of needles extending across the width of the machine (Figure 9b). Two common types of warp knitting machines are the Tricot and Raschel machines. Raschel machines are useful because they can process all yarn types in all forms (filament, staple, combed, carded, etc.). Warp knitting can also be used to make pile fabrics often used for upholstery. Back

KnittingTo form a fabric by the intermeshing of loops of yam.wale

course Wen hittingLoops are formed by needles knitting the yam across the width Each weft thread is fed at right angles to the direction of fabric formation. .- of the fabric.9-2 Knrmng Fmdamentals

Warp KnittingLoops are formed by needles knitting a series of warp yarns

fed parallel to the direction of fabric formation.Wale In warp knitting all needles knit simultaneously for all yams,

while in weft knitting the needles knit in sequence for each yam.Knrmngkvrdamentals 9-3

Figure 9- 1 Weft (Circular) Knitting And Warp Knitting

. .IConsumer AcceptanceComfortable Pliable High extensibility Easy care properties Inexpensive Apparel, home fashion, industrialKnmtng Furdamentals 9-5

Productivity And lead limeFaster than wovens Shorter lead time, quick response

Smalllots Body sizes, Full fashion0

Comparison of weft and warp knitting - Yarn feeding and loop formation - The two industries - Productivity - Machine design - Comparison of patterning and fabric structures - Course length and run-in per pack - Fabric quality - Structural modifications commonly used in weft and warp knitting

Knitting is a method by which thread or yarn may be turned into cloth. Knitting consists of loops called stitches pulled through each other. The active stitches are held on a needle until another loop can be passed through them. Knitting may be done by hand or by machine. By hand, there are numerous styles and methods. Flat knitting, which can be done on two straight needles or a circular needle, produces a length of cloth, while circular knitting, which is done on circular or doublepointed needles, produces a seamless tube. Different yarns and knitting needles may be used to achieve different end products by giving the final piece a different colour, texture, weight, or integrity. Using needles of varying sharpness and thickness as well as different varieties of yarn adds to the effect. Contents [hide]

1 Structure o 1.1 Courses and wales o 1.2 Weft and warp knitting o 1.3 Knit and purl stitches o 1.4 Right- and left-plaited stitches o 1.5 Edges and joins between fabrics o 1.6 Cables, increases, and lace o 1.7 Ornamentations and additions 2 Types o 2.1 Flat knitting versus circular knitting o 2.2 Felting 3 History and culture 4 Knitting in Advertising 5 Properties of fabrics o 5.1 Texture o 5.2 Colour 6 Process 7 Materials o 7.1 Yarn 8 Tools o 8.1 Needles 8.1.1 Record o 8.2 Ancillary tools 9 Industrial applications 10 Graffiti 11 Charity 12 See also 13 Notes 14 References 15 External links

StructureCourses and wales

Structure of stockinette, a common knitted fabric... The meandering red path defines one course, the path of the yarn through the fabric. The uppermost white loops are unsecured and "active", but they secure the red loops suspended from them. In turn, the red loops secure the white loops just below them, which in turn secure the loops below them, and so on.

Alternating wales of red and white knit stitches. Each stitch in a wale is suspended from the one above it. Like weaving, knitting is a technique for producing a two-dimensional fabric from a onedimensional yarn or thread. In weaving, threads are always straight, running parallel either lengthwise (warp threads) or crosswise (weft threads). By contrast, the yarn in knitted fabrics follows a meandering path (a course), forming symmetric loops (also called bights or stitches) symmetrically above and below the mean path of the yarn. These meandering loops can be stretched easily in different directions, which gives knitting much more elasticity than woven fabrics; depending on the yarn and knitting pattern, knitted garments can stretch as much as 500%. For this reason, knitting was initially developed for garments that must be elastic or stretch in response to the wearer's motions, such as socks and hosiery. For comparison, woven garments stretch mainly along one direction (the bias) and not very much, unless they are woven from stretchable material such as spandex. Knitted garments are often more form-fitting than woven garments, since their elasticity allows them to follow the body's curvature closely; by contrast, curvature is introduced into most woven garments only with sewn darts, flares, gussets and gores, the seams of which lower the elasticity of the woven fabric still further. Extra curvature can be introduced into knitted garments without seams, as in the heel of a sock; the effect of darts, flares, etc. can be obtained with short rows or by

increasing/decreasing the number of stitches. Thread used in weaving is usually much finer than the yarn used in knitting, which can give the knitted fabric more bulk and less drape than a woven fabric. If they are not secured, the loops of a knitted course will come undone when their yarn is pulled; this is known as ripping out, unravelling knitting, or humorously, frogging[1]. To secure a stitch, at least one new loop is passed through it. Although the new stitch is itself unsecured ("active" or "live"), it secures the stitch(es) suspended from it. A sequence of stitches in which each stitch is suspended from the next is called a wale.[2] To secure the initial stitches of a knitted fabric, a method for casting on is used; to secure the final stitches in a wale, one uses a method of binding off. During knitting, the active stitches are secured mechanically, either from individual hooks (in knitting machines) or from a knitting needle or frame in hand-knitting.

Weft and warp knittingSee also: Warp knitting There are two major varieties of knitting: weft knitting and warp knitting.[3] In the more common weft knitting, the wales are perpendicular to the course of the yarn; however, in warp knitting, the wales and courses run roughly parallel. In weft knitting, the entire fabric may be produced from a single yarn, by adding stitches to each wale in turn, moving across the fabric as in a raster scan. By contrast, in warp knitting, one yarn is required for every wale. Since a typical piece of knitted fabric may have hundreds of wales, warp knitting is typically done by machine, whereas weft knitting is done by both hand and machine.[4] Warp-knitted fabrics such as tricot and milanese are resistant to runs, and are commonly used in lingerie. Weft-knit fabrics may also be knit with multiple yarns, usually to produce interesting color patterns. The two most common approaches are intarsia and double knitting. In intarsia, the yarns are used in well-segregated regions, e.g., a red apple on a field of

green; in that case, the yarns are kept on separate spools and only one is knitted at any time. In the more complex double knitting, two or more yarns alternate repeatedly within one row and all the yarns must be carried along the row, as seen in Fair Isle sweaters. Double knitting can produce two separate knitted fabrics simultaneously, e.g., two socks; however, the two fabrics are usually integrated into one, giving it great warmth and excellent drape.

In the knit stitch on the left, the next (red) loop passes through the previous (white) loop from below, whereas in the purl stitch (right), the next stitch enters from above. Thus, a knit stitch on one side of the fabric appears as a purl stitch on the other, and vice versa.

Knit and purl stitchesIn securing the previous stitch in a wale, the next stitch can pass through the previous loop either from below or above. If the former, the stitch is denoted as a knit stitch or a plain stitch; if the latter, as a purl stitch. The two stitches are related in that a knit stitch seen from one side of the fabric appears as a purl stitch on the other side. The two types of stitches have a different visual effect; the knit stitches look like "V"'s stacked vertically, whereas the purl stitches look like a wavy horizontal line across the fabric. Patterns and pictures can be created in knitted fabrics by using knit and purl stitches as "pixels"; however, such pixels are usually rectangular, rather than square, depending on the gauge of the knitting. Individual stitches, or rows of stitches, may be made taller by drawing more yarn into the new loop (an elongated stitch), which is the basis for uneven knitting: a row of tall stitches may alternate with one or more rows of short stitches for an interesting visual effect. Short and tall stitches may a