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| Issue date:01/02/2006 |
| ATA Journal for Asia on Textile & Apparel - Feb 2006 Issue |
| Source:Journal for Asia on Textile & Apparel |
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| Seamless knitting garment can now be further customized with the use of CAD systems, textile inkjet printers and embroidery machines, writes Dr Sanjay Gupta |
The technology of knitting seamless garments on V-bed machines have gained significant commercial acceptance since its introduction in 1995. Besides offering higher comfort and better fit to consumers by eliminating seams, the innovative technique creates entire garments with minimal intervention of cutting and sewing processes leading to substantial savings in cost and time, higher productivity, quick response and just-in-time production.
Based on such technology, mass customization is enabled, which allows consumers to decide on the features of a garment. For woven products, they can be digitally designed; patterns digitally made; markers can be created; and fabric can be digitally printed. After printing, however, the fabric must be cut into its component parts and sewn.
On the contrary, knitting a complete garment on these new seamless machines allows the product to remain in digital form until it reaches the manufacturing/conversion plant. This ability to communicate digitally offers the potential to completely change the concept of a factory.
Instead of a configuration where, say, 150 of these machines are working in one place, today it is conceivable to geographically distribute these same 150 machines in department stores across the city. And if there were enough demand to keep this single machine running, then the traditional factory concept would not be necessary.
Shima Seiki, manufacturer of computerized WholeGarment knitting machines, has tested the digital factory concept in Japan. The company offers "an original, one-of-a-kind sweater just for you" in Japan's knitwear market through their Knit Factory Boutique - a production factory and retail boutique combined in one facility.
This revolutionary hybrid set-up offers complete on-demand production of customized items designed and fitted perfectly to suit individual customer. Also found on the premises are a printing system and embroidery machine, offering even further personalization of knitwear. The boutique is located in a three-storey building. One floor contains a couple of knitting machines. Another floor has designs and samples to assist customers in making decisions regarding the products they want. The third floor is a customer lounge where garments can be tried on in a virtual environment.
The concept is for customers to select a design and see how it might look in a particular setting. Changes can then be made, and the digital file can be used to drive the in-store knitting machines. These steps take only about an hour or two, depending on the styles, colors and patterns selected. The completed product can be picked up by the consumer at the agreed time. Prices range from 15,000 to 30,000 Japanese Yen, which are comparable to high-quality items sold in department stores.
The project is being considered one of the most promising forms of retail fashion next to electronic shopping via the Internet. Once a customer places an order, his or her measurements and preferred designs can be input into a customer database, so the likelihood of repeat orders is very high. The project is not just about a profitable retail store, however. It is about integration of cutting-edge technologies in knit designing, graphic programming, simulation, whole-garment programming and manufacturing, and value addition through printing and/or embroidery. The recent innovations in CAD, seamless manufacturing, inkjet printing and embroidery that have made it possible are being discussed here.
Developments in CAD systems
An important aspect of mass customization is that the consumer is able to express and get his/her choice of garment style, design and pattern. The interface between the knitwear designer and the knit technician is therefore critical to the development of new samples. The designer's concept sketch must eventually be realized on the machine through the capabilities of the technician. Up till now computerized machine makers have been focusing on the knit programming module where a trained technician creates a pattern on a dedicated CAD system that saves the data on a diskette, which is transferred to machine, and manufacturing starts. It is only in the past few years that the top two computerized knitting machine makers i.e. Shima Seiki and Stoll have focused their energies on establishing the interface.
Shima Seiki has enhanced the interpretative process in their SDS ONE CAD integrated knit production system that allows all phases including planning, design, evaluation and production. Knit designs are created in the paint program and are simultaneously converted to programming data. Various combination of knit structures and yarn selections are available in the design system that allows virtual simulation without actual knitting. There is also a pattern structure database of knitted parts like collars, plackets and cuffs through which parts can be incorporated or changed at will.
Stoll's M1 CAD system, on the other hand, has tried to establish communication between designer and technician by offering two different windows for designers and technicians who need different information for the same design. The technical window shows the developing design in the form of running yarn notations and technical data while the design window presents design as a knitted structure. Both windows are easily displayable and automatically convertible.
WholeGarment sleeveless pullover from Shima Seiki |
Developments in knitting machines
Both Shima Seiki and Stoll offer comparable solutions for the knitting of complete garments on computerized V-bed knitting machines. Shima Seiki's WholeGarment range of machines has range of gauges from 5 to 18 needles per inch and knitting widths ranging from 50 to 80 inches. Stoll's Knit & Wear machines have gauges ranging from E2.5 to E9.2 and knitting widths between 72 to 84 inches. Both offer multiple gauge system, which permits different gauge areas to be knitted in one single course. The technology allows the combination of many different patterns within one garment, which cannot normally be accomplished on a traditional knitted garment. For example, a jersey knit can be placed side-by-side with a mesh knit, which can be placed side-by-side with a rib knit, which can be placed side-by-side with a jacquard knit, and so on.
This year Stoll has filed a patent describing a technique for manufacturing seamless garments using the same needle space as the body width for their Knit & Wear machines. With the new technique the sleeves are knitted subsequent to the body, using the needles previously used in knitting the body. Narrowing is performed without fashioning, using what Stoll refer to as the "gore" technique. This technique is sometimes also referred to as "flechage" or "short-row" knitting and involves knitting successively shorter rows to narrow or impart shape into a fabric. Since carriage strokes are shorter compared with the conventional Knit & Wear technique, knitting time is reduced. Production time is reduced because the knit and transfer traverses required to join the sleeves to the body are not needed in this case. Joining is carried out in the gore technique.
On-demand inkjet printing of knitwear
A recent development that has created great interest among knitwear manufacturers and buyers alike is on-demand inkjet printing system for knit fabrics. While Shima Seiki SIP-100F features a height-adjustable printing head that prints not just circular knit fabrics but also dimensional flat-knitted fabrics and finished garments, Brother GT-541 and SWF East Fast T-Jet printers are simpler machines aimed at printing T-shirts only. Both enable full color printing on a variety of knit fabrics, using design data created on their respective CAD systems. Unlike conventional dyeing and printing systems, which are unsuited to small-lot production, or bulky transfer prints, which alter the texture of the original fabric, the inkjet printing uses advanced piezo inkjet technology that is simpler and faster. It is also less expensive because there is no extensive set-up, teardown, clean up, screens, squeegees, or pallet adhesive.
GT-541 garment printer |
The Shima Seiki SIP-100F was originally developed to enhance Shima's WholeGarments, which are predominately single color garments. The SIP-100F has a maximum print head speed of 0.7m/s (approx. 8.5min/sqm) and uses high-speed, wide-nozzle, printing in both directions over a maximum print area of 160cm x 100cm. With a head height range of 3 to 50 mm and laser fabric-height sensor, the SIP-100F can handle knitwear and knitted fabrics in a wide range of gauges and thickness as well as completed products, including seamless knitwear, which is produced in one entire piece. Additionally, the SIP-100F is fitted with a CCD camera required for accurate positioning of the print head when printing one side of a garment and then the other where for example the print design wraps around the sleeve.
Both reactive and disperse dyes are supported for printing on different types of fabrics. The printing process, like most printing technologies does, however, involve additional pre- and post-printing treatments. Firstly, the garment or fabric has to be washed to remove oil and impurities from the fabric for stabilizing print quality. The fabric is then treated with a pre-treatment fluid, which varies according to the fiber content and dyestuff to be printed. The post printing process involves steaming to fix and enhance color, which takes approximately 12 minutes for cotton and 30 minutes for wool, which is followed by washing at 80°C for cotton or 50°C for wool.
The clarity of prints is reportedly so good that close inspection is required to distinguish between printed and knitted designs. Additionally high-resolution photographic type images can be printed easily across a range of gauges and fabrics.
The Brother GT-541 is a large ink jet printer that prints on most garments in full color directly from a computer, with a 14" by 16" printable area. The SWF East Fast T-Jet printers are similar and use pigment inks to print on white, light and dark shirts. In addition to standard T-shirts, thick items like sweatshirts and hooded shirts can also be printed. The size varies with the model and can go from 12" x 12" to 12" x 21". These ink jet printer are as simple to operate as a desktop printers; and the durable water-based inks can be cured by a standard heat press, eliminating the need to purchase a conveyor dryer, and withstand repeated washings.
Brother's PR600C single head portable embroidery machine |
Embroidery for value addition
Embroidery, besides printing has enormous possibilities for value addition on knit garments particularly in the embellishment of ladies knitwear. Brother offers PR-600C, a 6-needle single head portable embroidery machine and BE-1201B-AC, a 12-needle industrial single head embroidery machine for the purpose. PR-600C is compact enough to fit anywhere at homes or shops and lightweight enough to take with you on the road. It offers easy operation, six needles, automatic color change, automatic top and bottom thread trims, embroiders caps and tubular garments, has a 12" x 8" embroidery area, and sews at a maximum speed of 1,000 spm. BE-1201B-AC is specifically designed for sewing patterns and has a control panel that simplifies the use of machine functions. A pattern can be embroidered by simply selecting the desired pattern from a maximum of 45 patterns.
Conclusion
Trends in supply chain management indicate that mass customization strategies are infiltrating all types of companies and are rewriting the rules about how products and services are becoming inseparable. In addition, the potential impact of such breakthrough technologies as body scanning, virtual dressing, digital knitting and digital printing are just beginning to be felt. Better understanding these methodologies will no doubt strengthen the vision of a totally digital supply chain. Some work has yet to be done, however, before knitwear manufacturers will purchase these systems in numbers. The possibilities are enormous and this technology is definitely one that knitwear manufacturers and buyers will be following closely.
Dr Sanjay Gupta is a Professor at the Fashion & Textile Programme of National Institute of Fashion Technology, New Delhi, India.
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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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