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| Issue date:08/04/2010 |
| ATA Journal for Asia on Textile & Apparel - Apr 2010 Issue |
| Source:Journal for Asia on Textile & Apparel |
| by Sanjay Gupta |
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| There has been great interest in the development of seamless shaped knit garments recently. A shaped knit product has a number of advantages over the traditional cut and sewn product in terms of raw material savings, high productivity in manufacturing, higher quality and performance of product and the high potential for innovations in new product developments. |
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| Machines of Sangiacomo knit men's and children's socks. Pictured is Fantasia 2C HT |
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There are a number of different machines that can produce "haped" knit products seamlessly. Typically, some of these machines totally eliminate the cut and sew process, while other minimizes them to produce a garment with fewer seams. Seamless machines have evolved over time in different stages. They all co-exist even now, broadly divided into three categories—each having a different level of sophistication. One category of machines produce shaped panels such as the front and back bodice and sleeves that are sewn together to produce a garment with other details such as collars and pockets being added during the sewing process. These machines are shaping or full-fashion machines. Integral knitting machines are similar to full-fashion knitting except that they can also add trims, pockets and other details such as button holes during the knitting process. The last and most sophisticated machines are referred to as wholegarment machines (a term coined and now registered by Shima Seiki) where a whole garment is produced directly from the machine without any cutting or sewing.
Since wholegarment knitting debuted more than a decade ago, there have been continuous improvements in machine design. The machines today have unique design capabilities by virtue of their control on individual stitches within a course. A wide variety of constructions, from a sheer to bulky knit fabric can be produced. Needles can be taken out of action to knit fabrics of different weights. These machines can be equipped with intarsia carriers programmed to knit in designated areas as opposed to knitting the full width of the machine. Using intarsia carriers, multi-gauge looks and combinations of design structures can be seamlessly incorporated within a garment to enhance comfort and performance. Multiple gauges allow for a wide variety of yarns to be used, together.
Open structures can be incorporated in specific areas to give the wearer additional ventilation. Transfer mechanism for creating shapes can also be used to produce elegant knit constructions such as pointelle—a knit fabric with a pattern of holes or openings made by using transfer stitches. Extra warp insertion mechanism allows interesting color combinations and patterns such as vertical stripes and jacquards to be combined with intarsia patterns to provide a range of fashionable garments.
Application areas in apparel include activewear, outerwear, swimwear, lingerie, hosiery and shapewear.
With the ability to produce almost any seamless shape, however, the technology has opened the potential in a variety of markets other than apparel. The inherent stretch in seamless fabric can be used in upholstery market to give seat covers an excellent smooth appearance with substantially lower lead times. Shaped tubular constructions find extensive use in medical applications like massaging and shaping products, protective products before and after staying in hospital, compressing garments pre/post child birth, bandages and a range of garments geared toward promoting wellness. Along with the use of high-performance fibers and electronic sensors, these products are expected to witness a high growth.
Working faster with seamless manufacturing
Santoni's SM12 single jersey electronical circular machine with 12 feeds with 3 selection points per feed |
Shima Seiki and Stoll are the two of the leading manufacturers of flat V-bed whole garment knitting machines. Shima Seiki's latest offering in WholeGarment seamless flat knitting technology is MACH2X that offers more than twice the productivity of previous versions. The machine was shown at ShanghaiTex 2009, knitting a ladies' pleated pullover with structured design in less then 24 minutes. The machine is claimed to be capable of sustained knitting speeds of 1.6 m/s. Stoll has been improving on the productivity of its Compact Class CMS flat knitting machines. Its two new entry models include the CMS 502 and CMS 502 multi gauge, featuring two knitting systems, a 45-inch working width, take-down comb, cutting and clamping on the right side, yarn feed on the left side, moveable display slide, additional yarn control units, two adjustable plating yarn feeders, adjustable main take-down, increased productivity, and gauges ranging from E5 to E18. Stoll is also offering accessories and software solutions, including intarsia kits, plating yarn feeders and kits, a new automatic stitch control yarn measuring device, and enhanced pattern software.
Santoni and Sangiacomo, both owned by Lonati, are manufacturers of circular knitting bed machines capable of producing shaped panels. Santoni’s are body size circular knitting machines, which are typically 10-24 inches in diameter. The machine knits a tube and imparts shape to the garment by incorporating combinations of float, tuck and knit stitches within the fabric. Incorporating different constructions within the fabric, such as false ribs, will also cause the fabric to bunch up, ultimately creating shape.
Shapes are also produced by knitting stitches of varying lengths or unbalanced stitches. With this technique, specified needles are programmed to pull a longer stitch, while others knit a shorter stitch. Many Santoni garments are sleeveless as they are used in intimates. Where sleeves are required such as in sportswear, sleeves need to be knitted separately on the same machine or a similar machine and are attached by sewing after the knitting process. Although some sewing is made to complete the garment, knitting cycle times are comparatively fast.
New electronic seamless circular knitting machinery from Santoni includes the SM8 and SM12 single-jersey, as well as the SM9 series double-jersey machine that can process a whole range of yarns from natural, man-made-fiber and covered elastic yarns. All models offer high rate of production of single body-size garments with high-definition patterns in distinct colors.
The SM9-MF of Santoni is for seamless ribbed underwear and outerwear with single welt and separation yarn. SM8-TR1 seamless transfer machine is used for the production of Santoni's patented fish-net or anti-drop stitch structures for swimwear, sportswear and sanitary wear garments. TL2 can knit a single or double welt carried out with jacks, in several selections, with knitted, floated or laid-in elastic yarn. The machine has a reciprocating movement, which allows it to knit intarsia in a similar way to a flat knitting machine with one- to four-needle overlap or tuck joins. The machine is being offered for creation of medical and sportswear garments with zones having varying compression levels. The major advantage being that these garments will provide excellent 'next to skin' comfort thanks to seamless intarsia joins and that compression nature of the garment.
Seamless warp-knitting reduces labour needs
Another category of seamless knitting technology, which also has been around for decades but has recently emerged into seamless fashion category, is that of warp knitting. Karl Mayer, the pioneer of this technology, as well as a handful of warp knitting machinery builders like Liba and Nippon Mayer, are offering narrow-width double-needle bar raschel machines for seamless warp-knitted lingerie and hosiery based garments. In 2008, Santoni too entered the field with their double needle bar warp knitting. Especially useful in knitting full-sleeves sportswear, these machines knit the sleeves integrally thus saving around 10% of labour involved in the cut and sew operation.
DJ machines from Karl Mayer and Nippon Mayer |
Seamless warp knitting technology uses two opposing needle bars equipped with compound needles, which are fed yarns by moving guide bars. Warp yarns, selected via the electronic selection system and piezo elements are presented to those needles to be knitted. Knitting commences with the knitting of three tubes side by side (sleeve/ body/ sleeve), which are created by knitting on both needle bars and by closing each tube at the edges by knitting. Knitting then continues to the underarm position at which point knitting proceeds in a single tubular fashion up to the neck opening. The shoulder shape of the garment is created by joining of the knitting of both needle bars in a predefined pattern within the tube. When the neck opening has been reached, the cycle starts over again to commence knitting of the next garment upside-down. To convert the lengths of body blanks into garments, the waste sections are removed by cutting and the shoulder line, which was created by joining the knitting of both needle bars, acts as a seam. Each garment blank is separated from the other by a simple horizontal cut.
Karl Mayer and its subsidiary, Nippon Mayer, offers double needle bar machines, the compact DJ series, DJ4/2 and DJ6/2(EL) in narrow working width of 44 inches and gauges E 24 and E 28. The EL system enables patterning to be carried out with a high degree of flexibility. Santoni offering is named SWD4/2J double needle-bar raschel knitting machines. It offers a working width of 44 inches in 24 gauges (needles per inch). Santoni is promoting SWD4/2J as a mini garment knitting factory, which the manufacturers can use to switch production from outerwear such as sportswear to lingerie to hosiery at will. Hosiery manufacturers with existing Santoni or Sangiacomo circular hosiery machines could install an SWD4/2J machine in a corner of their factory (it uses around six square metres of space) to start producing outerwear such as sportswear. The company could buy yarn on 21-inch beams from a commission warping operation and then send its garments out to a garment finisher. When the sportswear order has been completed the machine could then be switched to produce, for example, fancy hosiery.
A potential for warp knitting is in market segments where garments are required to have sleeves. There is a clear advantage for the manufacturer who can reduce production costs whilst being able to offer the customer a unique product.
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| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
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| Copyright © Adsale Publishing Limited. Any party needs to reprint any part of the content should get the written approval from Adsale Publishing Ltd and quote the source "ATA Journal for Asia on Textile & Apparel", Adsale Textile English Website - www.AdsaleATA.com. We reserve the right to take legal action against any party who reprints any part of this article without acknowledgement. For enquiry, please contact Editorial Department. |
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