Textile Progress
`
`ISSN: 0040-5167 (Print) 1754-2278 (Online) Journal homepage: www.tandfonline.com/journals/ttpr20
`
`4. Knitting Overview
`
`D. L. Bailey & J. L. Grow
`
`To cite this article: D. L. Bailey & J. L. Grow (2000) 4. Knitting Overview, Textile Progress, 30:1-2,
`41-50, DOI: 10.1080/00405160008688883
`
`To link to this article: https://doi.org/10.1080/00405160008688883
`
`Published online: 28 Nov 2010.
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`4. Knitting Overview
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`D.L. Bailey and J.L. Grow
`
`Cotton Incorporated, Raleigh, NC, USA
`
`4.t INTRODUCTION
`Machinery offerings at the ITMA '99 in Paris were focused primarily on innovations to improve
`the science of knitting through control of the knitting process. These innovations will result in
`more flexibility to the knitter, more output in first quality fabrics, higher production efficiencies,
`higher production speeds, and more profit. Achievement of these goals is a direct result of the
`machinery manufacturers having engineered into the process the aspects of increased and
`improved automation, better-built machines, improved and 'next century' electronics, aerospace
`metals in machine components, and simplified operation. Versatility and the ability to change
`styles quickly were the main focus of most manufacturers of knitting machinery. In addition to
`manufacturing better machinery, the conunitment to partnerships between the machine manufacturer
`and the knitter has become a focus of the machinery companies. Custom building of cylinders and
`dials, take-ups, wider cylinder diameters, on-machine quality monitoring, and precision
`interchangeable parts are all examples of a commitment to the customer. Because of increased
`worldwide competition among knitters, it is imperative that the knitter be able to expand
`productivity, increase efficiency, and become both more versatile and flexible. These necessities
`for the knitter are more achievable than ever because of the offerings of the machinery
`manufacturers at ITMA '99.
`
`4.2 CIRCULAR WEFT KNITTING
`4.2.1 General
`Weft knitting was well represented at ITMA '99, in both the circular and flat bed knitting sciences.
`Circular weft knitting continues to be the leader in the mass production methods for knitting. Flat
`bed knitting has controlled the areas of full-fashion, accent fabrics, garment panels, and specialty
`items. ITMA '99 displayed the latest in both weft sciences, with the exception of sock and hosiery
`machines. A common feature of both systems is the reliance on electronic computer control. These
`developments have simplified the entire knitting science by their use, not only in machine
`monitoring and needle selection for patterning, but also in control of the machine, including style
`changeover.
`
`4.2.2 Increased Production Rates
`To increase production off a knitting machine, one must either increase the number of feeds, the
`revolutions per minute of the cylinder, the diameter of the cylinder, or the efficiency of the process.
`Speeds have increased over the years and now have reached a maximum at 45-50 r/min on single
`knit machines of 30-inch diameter. When expressing speeds in terms of meters per second, the
`rates have reached 1.8 to 2.0. Higher speeds require a premium on the quality of the yam package,
`the quality of the yam, the heating of the cylinder, and the ability to start and stop the machine,
`especially those with larger fabric roll capacities.
`Realistic speeds for knitting cotton yams on single knit machines will be in the 30-35 r/min
`range and up to 40 r/min for 30-inch diameter interlock machines.
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`Feeder density has appeared to maximize at 4.0 feeders per diameter inch. The density of feeds
`is related to construction versatility, the type ofyam being knit, and fabric spirality. The range of
`stitch lengths is greatly reduced when high feed densities are used. This is because the steep cam
`angles involved put tremendous stress on the yam and knitting elements. Modification of the
`needles is also affected. Therefore, the optimum limit in knitting is normally found at 3.0 feeders
`per diameter inch, especially for spun yams.
`
`4.2.3 Electronics in Knitting
`4.2.3.1 General
`Electronics in knitting allow for a true man-to-machine interface. Fabric set-up and style changes
`have taken on a new level of efficiency due to that interface. Fabric monitoring during knitting is
`ensured by continuous reports on the state of the machine. Production numbers that are
`immediately available to the knitter and the management team are maintenance, quality, and defect
`information. Not only is monitoring possible by the operator, but monitoring can now be
`performed by the computer on the machine. These smart systems make constant checks on the
`progress ofthe process, and they also stop the process when production parameters fall outside
`ofthe prescribed limits.
`
`4.2.3.2 Electronic Supervision Systems
`Machines of today are now equipped, not only with electronics to monitor basic machine
`functions, but also with electronics that measure machine parameters and stop the machine if
`standards are not met. In addition, many fully electronic machines are able to make style changes.
`Among those machine parameters that are monitored are the operation of needle detectors, the
`operation of latch openers, course and stitch length, yam tensions, the operation of quality wheels
`and tape feeders, take-down tensions, cylinder temperature, oiler pressures and the operation of
`other machine functions. Fabric parameters that are monitored include defects such as barre and
`needle lines, among others. Shown at ITMA '99 were integrated monitoring systems foryam input
`and yam tensioning. Coni IN and Coni TM were shown by Mayer & Cie [1]. These systems are
`integrated to give positive yam infeed measurements. This data is transmitted directly to the
`process controller. These systems are used with Mayer's MCTmatic monitoring system, to control
`the yam input, the yam tension, quality wheel settings, stitch formation, and fabric takedown. The
`result is more consistent fabric quality. Also, when style changes are required, these systems allow
`for fast and simple resetting of different fabric parameters. By keying or entering one command,
`all the necessary settings for a given style, such as yam input tension, stitch length, central
`adjustment of belt tension, and quality wheel adjustment, are carried out automatically.
`These systems are operated by a main process controller. Based on inputted commands, the
`system will automatically adjust the quality wheel. The belt tension will be adjusted pneumatically.
`Yam input tensions are constantly measured and corrected through a positive yam feeder and
`stitch cam adjustment. Finally, the fabric takedown is positively driven and adjusted. Central
`control (MCTmatic) is also part ofthe quality assurance. Quality data is specified on the screen
`and is constantly monitored. Deviations out of tolerance will stop the machine automatically, with
`the error identified for the mechanic to address. As a result, the fabric weight and stitch counts
`remain constant.
`
`4.2.3.3 Electronic Needle Selection
`New machines are being equipped with the latest advances in electronics and computer controls.
`One ofthe most exciting features shown at ITMA '99 was the debut of electronic needle selection
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`on the dial of double knit machines. This choice of independent needle selection, and the use of
`the three-way technique of needle selection (knit, tuck and welt) at eaeh feed, creates many new
`design and fabric opportunities. The use of electronic needle selection on the dial allows for
`fabrics to be produced with full Jacquard patterns on both the technical face and baek ofthe fabric.
`The electronic dial capabilities include miss, knit, and tuek. Eleetronic needle selection on the dial
`is offered by several manufacturers. With the capability of electronic needle selection on the dial
`as well as the cylinder, every needle can be selected. Not only can double-sided Jacquard fabrics
`be developed, but Jacquard selection on the dial affeets the construction of the technical face,
`resulting in new design possibilities. These new designs will result in textural and smooth motifs
`not previously achievable in doubleknits.
`Another advantage of electronic needle selection on the dial is the ability to simplify the
`designing and manufacturing of two-faced constructions. For Jaquard constructions, the electronic
`needle selection on the cylinder and dial allows for quick and simple style changeovers. Other
`applications of electronic needle selection are the rapid changeover to and from Jacquard to basic
`fabrics. For example, when there is no demand for Jacquards, the machine can be easily set to run
`various ribs - Ponte de Roma (rib-gated), Swiss Pique, and many other rib-grated constructions.
`Other advances in electronic Jacquard knitting are the ability to switch colors, change stitch
`structure, disengage feeders for sampling purposes, and preview patterns on the computer screen
`at the machine. The ability to switch colors by the selection of needles at each feed, instead of
`changing the yam position in the creel, is realized. The ability to change pattem dimensions on
`the machine by input messages to the computer has been improved so that the pattem may be
`reversed, inverted, mirrored, stepped, or changed, at the machine. The pattem can then be
`reviewed on the computer screen at the machine, or a sample can be produced for approval. Also,
`the number of feeders used on the machine may be reduced electronically for sample work in order
`to conserve yam where applicable or accommodate pattem repeats.
`
`4.2.3.4 Electronic Stitch Control
`With electronic needle selection on the dial as well as the cylinder, and electronic control ofthe
`quality wheel, fabric set-up time has been reduced to a fraction ofthe conventional time for style
`changes. Not only are time requirements reduced, but labor requirements are also reduced.
`Because of this, short runs will be more cost effective.
`On-machine sensors measure the course length with every revolution ofthe cylinder. These are
`typically mounted at several ofthe tape feeders on the machine. If the specified course length is
`not met, the computer will stop the machine and the knitter must address the problem before
`knitting continues. Some machines are eapable of automatically ehanging the quality wheel when
`a style change is made.
`
`4.2.3.5 Electronic Transfer and Striping
`These technologies have become much more user-friendly by design and function. Efforts have
`been fmitful in developing more simple and compact electronic striping systems. As a result, these
`mechanisms are easier to work on and to clean. Up to five selectors can be chosen for each feed.
`Yam threading has been made easier by machine assistance in grabbing the yam and threading
`it through to its proper position in the striper feeder. Most ofthe features developed for basic jersey
`machines have been applied to electronic striping.
`With the ability today of electronically selecting each needle in the cylinder, and with simple
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`dial cam adjustment from the outside, some manufacturers can offer new pattem designs with very
`little set-up time. Because of Windows-based computers using pattem design software with
`transfer capabilities and automatic four finger striping, new areas of fabric constmctions can be
`explored.
`
`4.2.4 Cam Systems
`Much effort has been applied to present cam tracks for needles and sinkers that are as closed as
`possible to outside environments. Tolerances and clearances are as exact as possible to allow for
`increased speeds, more consistent needle clearing, knockover, and stitch forming. Another result
`of precision cam tracks is less wear on the needles, jacks, cams and sinkers.
`Double-sided stationary exchange cams were shown that allow for simple, quick, and efficient
`changing of needle selection on the machine. These cams are easily accessible and interchangeable
`from the outside ofthe cam section. Each exchange cam system is made into a single unit. Each
`unit has two choices. There is a choice of a knit end with a miss end, or a tuck end with a support
`end. To change from knit to miss or the reverse, the unit is simply removed from the cam section,
`tumed around, and inserted back into the cam section. These cams can be chosen for knit, tuck or
`support. Fabric constmctions that includejersey, piques, plain rib, 2x2 rib, rib tuck, half cardigan,
`thermal, double face, and many other constructions can benefit from the use of these new cams.
`Other systems for quick cam changes were shown such as rotary drop cams. Monarch
`manufactures these systems to allow for quick changing ofthe cam selection from the outside of
`the section [2]. In addition, cam sections are now more interchangeable on the same machine and
`from machine to machine.
`Diagonally adjustable stitch cams have been developed by Mayer & Cie, and Vanguard [3].
`These cams are implemented to allow for constant needle clearance with the yam feeder.
`Therefore, yam carriers need little or no adjusting. The result is reliable knockover, even on
`lightweight knit constmctions or tightly knit constmctions.
`Mayer & Cie offer central stitch cam adjustment for maximum simplicity and time savings. The
`machine is adjusted to the fabric weight, or the desired stitch or course length, with a simple setting
`action. This can be performed by a single computer input command, or the adjustment of a central
`mechanical mechanism. The computer input would be to enter a new knitting parameter. The
`mechanical input would be a simple adjustment of a central bolt that adjusts the cylinder with
`respect to all the stitch cams at the same time.
`Mayer & Cie are utilizing a new cam material called Pemnal. This high-tech aerospace metal
`gives outstanding performance in knitting. It is unique because of dimensional stability at different
`operating temperatures, non-oxidizing properties, less wear on the cams and the needles, a harder
`surface, and better dissipation of heat. The result is control ofthe needles because of positive and
`constant needle clearance, gentler needle defiection in the cam way, and more consistent stitch
`forming. By having a consistent needle path, the yam feeders can be more accurately set in
`relationship to the needles.
`The advent of a twin cam track for sinkers with two butts allows for longer sinker and cam life.
`Double guidance ofthe sinker is claimed to give a 100% increase in the life ofthe sinkers. The
`effect is better sinker control, more exact loop formation, and better overall machine performance.
`With more exact loop formation in velour and pile constmctions, shearing waste will be greatly
`reduced, and missed cut loops will become less of a problem.
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`4.2.5 Automated Style Changes
`Mayer & Cie stood out at ITMA '99 by introducing a system to automatically set the dial cams.
`The dial cam settings are automatically changed by using a switching robot. The robot changes
`the dial selections at each feed to knit, tuck or welt. Mayer's' switching robot' allows for rapid and
`accurate setting ofthe dial cams when style changes are requested. The three-way technique is of
`importance for the dial to allow for knit, tuck, or miss. The robot is programmed to go
`automatically from cam section to cam section to set each cam in sequence. The result is an
`accurate, technician-free, style changeover in a matter of just a few minutes.
`Changes in timing between the cylinder and the dial have become easier with the addition of
`mechanisms to quickly adjust the timing. The timing can be changed from delayed to synchronized
`with a simple input at the machine controller.
`Adjustment and monitoring of dial height has become much easier with the addition of a central
`control. When style changes are needed, the dial height will be automatically changed to the
`specified number. A centrally-located gauge is conveniently located to display the dial height. As
`with all other machine parameters, the dial height can be seen on the screen with those machines
`equipped with a computer monitor. Knoekover depth can also be easily read from the outside on
`a scale. This feature will allow for precise and simple reproduction of settings.
`Precise and rapid setting of machine gating is also possible on the new technology. This is a
`big plus in manufacturing because the appearance of rib and interlock constmctions is very
`dependent on the setting ofthe gating. Also, knitting efficiency is directly related to proper gating.
`
`4.2.6 Quick-change Cylinders and Dials
`Quick-change systems for the cylinder and dial are being offered. The design ofthe machinery
`allows for machine components such as yam carriers and fans to be quickly moved or swung out
`ofthe way. The cylinder and/or dial may then be removed and replaced with minimal machine
`disturbance. Some companies allow for the yam carriers to be placed on a common ring or in
`sections to form a ring for ease of removal and setting. For single knit applications, the sinker ring
`can be readily removed with the cylinder. Obviously, quick-change capability will allow mills to
`change gauges on single and double machines in just hours for body-sized and large diameter
`machines.
`There is a trend to wider diameters in excess of 30 inches, not only for the production of knitted
`sheets, but also to increase machine production for other end-uses. For body sized fabrics, cylinder
`sizes range from 8 to 26 inches. Wide cylinder diameters of 38,40,42,48,54, and 60 inches are
`offered by several manufacturers. In addition, special orders for cylinder diameters and gauges
`can be made with most machinery makers.
`Cylinders on modem machines have self-centering cylinder bearings that lie in an oil bath, to
`compensate for cold and warm machine operation conditions. This allows for a consistently and
`accurately revolving cylinder. Because of the demand for quick-change cylinders, the self-
`centered cylinder is a must.
`Systems to cool the cylinder on jersey machines have progressed since ITMA '95. Savings in
`metal life (cams, needles, sinkers, etc.), the reduction in frequency of oiling, the amount of oil
`needed, and increased production, result in savings to the manufacturer. Another benefit is fewer
`fabric seconds due to oil spots and oil lines. Alandale introduced the FilterFlow 2000 at ITMA
`'95. This system has been improved and is now offered by Vanguard for most single knit machines.
`Some companies are offering machines with an extraction system that can remove dust, lint, and
`sludge from the cylinder, needles, and sinkers. Compressed air is used to dislodge and expel
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`contaminants, and suction is used remove and coltect ttiese items. Ctosed camming is the key to
`operating eittier of these systems to coot the cytinder and keep it clean.
`
`4.2.7 Yarn Control
`Mayer & Cie showed their new yam feeding device, the Coni EP yam storage feeder with positive
`feed or storage feed (negative) capabihties. The Coni EP yam storage feeder offers new
`capabilities in the eontrol of yam in knitting. It makes use of a totally new thread wheel with the
`capability to choose the wheel as a positive yam feeder or as a Jaequard feeder (negative feed).
`With combined yam feeding capabilities, only one unit per feed is required instead of two. This
`is important where available space above the knitting elements is limited and where both plain and
`Jacquards are knit on the same machine. With fewer machine components above the knitting
`elements, there are fewer opportunities for lint and other contaminants to accumulate. Parts costs
`are reduced because the new units can be used as either positive or negative feeders. Finally, style
`changes to and from Jacquard and plain are made by the simple tum of a switch, which results in
`less time and labor.
`All surfaces that the yams must pass over now have high-tech coatings to reduce friction and
`protect the yams. On some machines, yam carriers are mounted on a separate ring, to allow for
`an exact and consistent setting. Yam routes have been designed for fewer deflection points,
`thereby reducing variability in yam tension, yam hairiness, and lint generation.
`Proper yam feeding is essential in the knitting of elastomeric yams, especially in plaiting
`applications. Plaiting capabilities have been improved on dial feeds to optimize the elasticity of
`the yam at each feed. As a result, a more uniform fabric is produced with respect to appearance
`and stretch characteristics. Yam carriers are precision manufactured, with multiple holes properly
`aligned to allow for better plaiting as well as offering flexibility for design and functional effects.
`Many yam carriers are designed to swivel outward to simplify threading and service.
`
`4.2.8 Improved Take-up Systems
`One ofthe most improved components of a knitting machine has been the take-up mechanism.
`ITMA '99 revealed a new generation of systems that wind consistent rolls from start to finish and
`from doff to doff. Take-ups shown were fully adjustable with positive, motorized drives.
`Consistent and reproducible take-down tensions are possible by computer control of a potentiometer.
`Tension can be addressed above the take-up rollers to control the tension ofthe fabric coming off
`the needles, and can be addressed below the take-up to control fabric roll tension. The ability to
`maintain the same tension in the take-up is critical to consistency in knitting, especially for stretch
`fabrics. Take-up rollers are now being covered with a coating, usually rubber, and have fully
`adjustable spacers capable of controlling fabrics over the full working width of the knitting
`machine. Spacers help reduce the distortion ofthe edge ofthe knitted tube.
`Several companies are manufacturing automated slitting units for fabrics, especially those
`containing elastomeric yams. Automated slitters are usually used in conjunction with a take-up
`that rolls the fabric in either tubular or open form. Terrot [4] presented new technology that opens
`the tube after slitting, and rolls the fabric in a fully opened width under the take-down rollers.
`However, some manufacturers offer a system to plait the fabric into a bin. The fabric bin is located
`just beneath the take-down rollers.
`Folding and rolling devices are typically offered on machine diameters of 26 inches and up. In
`addition to the above technologies, some machines have a special edge device equipped with a
`roller system, to make sure no sharp folded edges are formed on tubular types of take-up. This
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`system does not spread the edge of the tube over a fixed wire spreader, but spreads the flat tube
`over a roller system. These rollers prevent loop distortion and overspreading, and therefore do not
`pinch the fabric edge. This type of system is designed specifically for stretch and sensitive fabrics,
`and greatly reduces friction and distortion. All of these systems allow for crease-free edges on
`stretch and other sensitive fabrics.
`Another trend in machine design is to offer the option of extra large rolls. Most machinery
`manufacturers offer roll sizes up to 920 mm (36 inches) in diameter. This is important to both the
`knitter and the finisher. In knitting, machine downtime for doffing is reduced, knitting efficiency
`is increased, and less labor is required. Dyers want long runs with very few seams where rolls are
`joined together. For jet dyeing, the situation of one roll per fabric strand in the dyeing machine is
`ideal. For continuous bleaching ranges, the longer the roll, the better for reducing the number of
`seams required.
`
`4.2.9 Pile Fabrics
`The production of fiill Jacquard pile fabric by means of full eleetronic sinker selection with high,
`low, and no loop options at each feed is the latest technology. The design of the loop sinkers and
`the camming systems allow for ease of application. Sinkers for forming the pile loop have been
`improved by sinker shape and by sinker activation with double guidance cams. Double guidance
`of the sinkers allows for more reliable loop height and less waste after shearing for velour fabrics.
`Also, better control of the sinkers in knitting allows for a smoother surface on the ground or jersey
`side of the stmcture. Better tension control in knitting and improved yam guides allow for a better
`pile tie-in to give consistent plaiting. The result is a fabric that has a smoother surface for napping
`on the ground side and nearer perfect shearing on the pile side.
`Eleetronic sinker selection allows for an unlimited pattem area for the pile. As with other
`improvements in electronic knitting, precise control of the sinkers results in less changeover time
`and higher knitting efficiencies. When Jacquard pattemed pile fabrics are not in demand, the
`Jacquard selection of sinkers allows for less down-time to change to basic constmetions.
`Pai-Lung [5] has developed terry machines that have a cylinder and a dial. These machines have
`an electronic Jacquard-controlled cylinder and a two-track mechanical dial. Another feature is the
`ability to cut the loops on the machine. The pile loop is formed on the technical face (cylinder)
`and the ground is formed on the technical back (dial). The ability to form the loops on the Jacquard-
`controlled cylinder allows for design pattems that contain both cut and uncut loops. Unique and
`interesting constmetions are therefore developed.
`
`4.2.10 Plush or Sliver Knitting
`Several maehinery companies had offerings of new plush (sliver) knitting maehines. The
`introduction of new technology in the production of high quality sliver knitting was the focus. The
`FiberKnit system shown by Mayer Industries [6], exhibited a system unlike any sliver knit machine
`manufactured in the past. The sliver knitting industry has been trying for decades to re-knit the pile
`back into the stmeture on successive courses with consistent quality. The new technology,
`FiberKnit, has aehieved this goal and provides the industry with technology that offers to be
`reliable, simple to operate, and capable of producing fabries that are innovative with consistent
`quality.
`The economic advantages of FiberKnit are numerous, and stem from re-knitting 95% of the pile
`baek into successive courses. Almost all of the fibermaterial is retained in the fabrie with very little
`fiber lost in finishing. Pile retention in finishing and consumer use is better because the fiber is
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`anchored twice into the ground ofthe fabric. This locking ofthe fiber into the ground reduces
`shedding, pilling, and, in most cases, the need for a back-coating. It is claimed that fiber loss during
`all conventional finishing can be as low as eight to ten percent. Knitting back into the stmcture will
`conserve material and reduce finishing costs.
`All the plush machines shown, including FiberKnit, are available with Jacquard design
`capabilities. Constructions may vary from fiat, to fleece, to plush, all from the same machine. Pile
`heights may be varied as a result of design effect. Fabric yields from 180 to 750 gm/m^ (5.25 to
`22 oz/yd^) are possible. Fiber staple from 25 to 35 mm (1.0 to 1.4 inches) are optimum for knitting.
`Apparel fabrics, home fumishings, upholstery, automotive, and industrial fabrics are all targeted
`markets.
`Machines shown are available in 10, 12, 14, 16, and 18 gauges, with 18 to 24 feeders. Each
`feeder has a three-roll carding unit. Two to eight colors are possible on most machines.
`Manufacturers offer electronic versions that can slit the tube on the machine and doff the fabric
`into a basket.
`
`4.3 FLAT BED KNITTING
`
`Knitting to shape and full fashion continues to advance in the fiat weft knitting sector. Stoll [7]
`presented touch control technology with their machines. Touch control technology was displayed
`for complete garments or panels. Symbols serving as icons are used to direct the functions ofthe
`machine. This is an effective means of operation since the symbols are multi-national in
`understanding. Multi-gauge and double-sided fabrics were shown, with multi-width panels.
`Therefore, full-fashion has been rebom in today's sophistication ofthe fiat knitting industry.
`Full-fashioning, loop transferring, rib shaping, integral knitting, and whole garment production
`are more prevalent today. However, panel produetion is still the most common form of fiat
`knitting. Whether a panel or a garment is made, it is possible to knit into the fabric pockets, closed
`pouches, collars, buttonhole panels, facings, overlapping collars, bows, and most any garment
`component imaginable. Mass production of complete articles such as socks, hats, mittens, and
`sleeveless shirts are of particular importance.
`The revolutionary slide needle was shown, which is patented new technology by Shima Seiki
`[8]. The slide needle achieves consistently centered loops with minimized yam tension. This new
`needle also allows for loop transferring and multiple-gauge designing. Multiple gauge or fiexible
`gauge knitting also offers free adjustment of loop size and wale spacing, to give additional freedom
`to knit designers. Fine to coarse gauge looks can be achieved in the same pattem.
`
`4.4 WARP KNITTING
`4.4.1 General
`The new generation of tricot and raschel machines shown at ITMA '99 exhibited an abundance
`of electronic controls, computer controls, and microprocessors, to enhance quality, efficiency,
`and production. Machine functions including control of guide bars, take-up mechanisms, and yam
`mnner lengths are all electronically controlled. This new generation of computer control gives the
`machines finer tolerances, allowing higher speeds and the capability of producing fabrics up to
`6220 mm (245 inches) wide. As a result, tricot and raschel equipment have found new markets and
`end-uses in building materials, geo-textiles, erosion control and reinforcement fabrics, automotive,
`medical, as well as home and apparel applications.
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`Today's warp knitting is not only in the filament nylon and polyester areas, but has expanded
`to such fibers as carbon, glass, metals, aramide, polypropylene, and polyolefins among the newer
`fabric fabrications. Unfortunately, with the exception of lace fabrics developed on raschel
`machines, spun yam fabrications were not shown. However, weft insertion machines can process
`spun yams for the apparel and the home products areas.
`Karl Mayer [9] and Liba [ 10] exhibited the latest developments in the areas of tricot and raschel,
`stitch-bonding equipment, and warp preparation. A circular loom from Mayer to manufacture
`bags, containers and tarps made of polypropylene was on display.
`
`4.4.2 Tricot
`High-performance tricot machines were shown for the knitting of elastic fabrics at high rates of
`speed. This has been made possible by making use of high-tech materials in the machine
`components ofthe knitting cycle. In addition, the use of electronics to control patteming instead
`of linked chain systems has also resulted in higher speeds through precise control. The result of
`these improvements is greater reliability, minimum defects, low energy consumption, low heat
`emission, low noise levels, a good price: performance ratio, and, of course, higher speeds.
`Improvements through innovation have also occurred in the control of yam from the warp beam
`through let-off and knitting. Digital control ofthe yams during let-off and positive feeding, results
`in a high degree of consistency and accuracy. Runner lengths can be precisely controlled during
`the entire run ofthe warp.
`Electronics for control ofthe yams for each guide bar, patteming, take-up, and defect analysis
`have greatly expanded the range of fabrics that can be made on even the most basic of machines.
`User-friendliness ofthe process controller on the machine has become a key part of warp knitting.
`
`4.4.3 Raschel
`High-performance raschel with weft insertion was shown that can produce wide industrial and
`technical fabrics. Working widths up to 5410 mm were shown, with magazine weft insertion
`capabilities. The wefl insertion system uses a servo-motor control to guarantee optimum speed and
`pattem capabilities. Speeds of up to 1400 r/m