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MECHANICAL PROCESSING

Introduction

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The wide variation and unique characteristics in jute fibre properties, and meshy structure made this fibre difficult in processing. Hence, its processing machineries are quite different than any other fibre processing machines. In earlier days, hand spinning of jute has been practiced in India to make thread and twine and also for weaving the coarser fabric for packaging material and matting. In 1830, the spinning machines were developed at Dundee, Scottland and this technology was transferred to India in around 1850.
 

Preparatory to Spinning
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In the preparatory to spinning of jute, there are several machineries involved in fibre formation from jute reed, their parallelisation, thinner fibre strand preparation etc. Basically, there is very little technological advancement in this part of spinning preparation. The conventional jute softener machines are manufactured by Urquahart Linsay, Parker, Angus, Doglus Fraser and Lee Croll. (Fig. 1). Their average speed is 18 m/min.  The spreader is made by Fairbairn, Lowson, Combe Barbour, James Mackie & Sons. The average delivery speed is 55 m/min. Due to improvement in jute quality, the number of pair of rollers have been reduced drastically to increase the productivity. The productivity and fibre processing have been improved in modern carding and drawing. The conventional carding machine (Fig. 2) is made by Lowson, Fairbain, J E Low, Lewis Fraser and Mackie. Modern cards are developed by Fraser (JF Series card with delivery speed 60-80 m/min.) and Mackie & Low (M series card with delivery speed 40-50 m/min), Milltex (with delivery speed 70-85 m/min). The modern carding machines introduce full circular finisher card with double doffer and gill drawing. M-series finisher card is introduced with a new type of feeding system consisting of rollers mounted with metallic card clothing. In drawing (Fig. 3), higher speed and better fibre control in the drafting zone are the main criteria of development. With these aim, push bar has been replaced by screw gill machines. Intersecting gill drawing has been introduced successfully in the industry. Later on, Mackie introduced monohead draftomatic drawing machine with autoleveller for better sliver quality. At present, rotary gill drawing (Fig. 4) of Hans Machineries is very much popular to the industry. The faller drops is as high as 800 /min for finisher drawing. The other manufacturers are J F Low & Co., James Mackie & Sons, Lagan jute machinery etc.

softener    card
jute drwaing    rotary gill drawing
 


Spinning
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Prior to 1950, rove spinning system was used to spin the fine quality jute yarn (about 180 tex). Due to tedious manual operation and low efficiency in positive spindle drive and also low production, rove spinning system was replaced by sliver spinning technology which often called ‘Flyer spinning’. Conventionally, slip draft with two-legged flyer and apron draft with tubular flyer are common in use. The main limitation of the two legged flyer frame is slow flyer’s speed and smaller package size. The maximum flyer speed of 4.25 inch pitch frame is 3600 rpm (fine yarn spinning) and that of 5.5 inch pitch frame is 2200 rpm (coarse yarn spinning). The above difficulty is overcome by the replacement of two-legged tubular flyer, which is also known as ‘Buxter flyer’ and is suitable for higher speed without fluctuation of tension in yarn. In this system, there is 15% more production than two-legged flyer frame. The flyer speed is raised to 4000 rpm for fine yarn production. At high speed, the control of fibre in the drafting zone is very difficult. The control of fibres in the drafting zone is improved by introducing the single apron with pressure in slip draft frame for finer jute yarn. The limitations of conventional flyer spinning systems lead to develop the modern technology of spinning for jute fibres. Conventional system is not suitable to produce very fine count with acceptable level of quality and machine efficiency at higher spinning speed. The lowest yarn count that can be spun from standard batch mixing on a slip draft frame is around 210 tex and that on the apron draft (Fig. 5) is 180 tex. The spinning rate cannot be raised generally above 30 m/min. In order to eliminate the above difficulties, the new spinning technologies have been evolved. The main objectives in modernization of spinning system are: (a) to increase the speed, (b) to decrease the irregularity in yarn, (c) to produce finer yarn, and (d) to reduce the manufacturing cost.

apron draft spinning

The ring spinning technology has been introduced in the jute industry. Double apron high drafting system is incorporated for better quality and productivity. There are number of manufacturers of jute ring spinning frames such as Fratlli Bolelli of Italy, James Mackie and Sons Ltd. of Belfast, O-M Ltd. of Osaka, Techmashexport of Russia, Weller of Germany etc. But jute ring frame has not yet been popular in industry due to high consumption of power than flyer spinning. Quality improvement is not much significant and not more than 6000 rpm of spindle speed is achieved because above that speed hairiness of jute yarn increases significantly. But this system is very much popular for the production of jute ply yarn. Heavy package Ring Twisting machine is made by Hans machineries.

The researchers have tried to use different modern spinning systems. Twistless yarn spinning has been tried using 3-5% (on the dry weight of yarn) water soluble bonding material (like Carboxy methyl Cellulose). The principle of twistless spinning is to spun the yarn in the form of a flat tape without having any twist in which the fibres are laid straight and parallel along the yarn length. The productivity is about 2 kg/hr. with 275 tex yarn. The areas of application of such yarns are carpet backing cloth, reinforcement of plastic composites and laminated products. But in this technology, application of bonding agent and drying process are additional processes and much expensive. Hence, twistless spinning system is not adopted by jute industry.

Spinning of 100% jute in rotor spinning (Fig. 6) is not successful due to machine limitation and jute fibre characteristics. But, successful attempt11 has been made to spin chemically treated stapled jute blended with viscose. It has improved the quality of yarn and production rate. The system is suitable for coarser yarn only. The main limitations of jute open end rotor spinning are the bigger rotor diameter for long jute fibre and rigidity of jute.

Rotor spinning

Hollow spindle spinning system (Fig. 7) is very much suitable for jute spinning. In this system a filament/fine yarn is wrapped over the parallel, untwisted, jute core. The count range is 50-500 tex, which can be spun successfully using high speed drafting system. The spindle speed is as high as 35,000 rpm and delivery speed is 200-300 m/min. James Mackie & Sons Ltd of Belfast, Spinael Fabrik Sussen of Germany etc are the manufactures of such machine. This yarn is particularly suitable for the majority of velour and plush type fabrics. It can also be used in tufted fabric, knitting and other areas where twisted yarns can be used.

Hollow SpindleSpinning

The friction spinning technology (DREF) has been tried to produce coarse yarns keeping jute in core and other natural or synthetic fibre in sheath (Fig. 8). The spinning speed is 200 m/min. The jute-based yarn manufactured in this system can be used in carpet, cables, shoe industries etc. Friction spinning has a good prospect in the field of jute-blended products.

DREF Spinning

Jute is facing challenge due to low profitability of conventional products and stiff competition from synthetic packaging products in the overseas and domestic markets. To overcome this situation, the idea of product diversification has been generated for last two decades. But, some adverse properties of jute restrict its wide use and economic viability. Major researches in this respect come out with the quality improvement due to blending of other natural (ramie, flax, pineapple leaf fibre, Banana, sunhemp, wool, coconut etc.) and synthetic fibres (polyester, viscose, acrylic, polypropylene etc.) with jute. It gives low cost, value added product out of jute and improves the spinnability and productivity. Now-a-days, jute is used in different fancy or decorative goods. It was observed, that jute fibre can be successfully blended with any fibre having variable length distribution between 100 to 150 mm. Microscopic studies reveal preferential migration of fibres when jute is blended with synthetic fibres. Jute can be blended in cotton or khadi machineries to spin upto 30s Ne yarn. In traditional jute industry, proper selection of processing machineries, process parameters, blending technology and process control techniques are required to produce value added high quality/fancy jute blended yarn which can be used in home textiles, technical textiles, apparel textiles etc.

Medi jute spinning machineries of Bhowmik Calculators and miniature jute spinning machineries of National Institute of Jute & Allied Fibre Technology (formerly JTRL) and New Central Jute Mills have been developed with lower production rate for decentralized small scale unit (Fig. 9).

Mini-carding    Mini-drawing    Mini-spinning

 


Preparatory to weaving
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Winding is done to make bigger packages (spool) fr0m small packages (bobbin) (Fig. 10). The conventional winding machine is made by Urquahart Lindsay, Fraser, Robertson, Orchar, Britania, Angus etc. These machines can achieve speed fr0m 135 to 170 m/min. Modern high speed winders contain traversing system by grooved drum and made by Mackie, Fraser, Oriental, Gardella etc. These machines can run in 270 to 550 m/min and they operate with tag ending bobbins. High density precision cross winding machine (chain traverse type) is developed by Forster, Hans machinery etc. These are capable to run at a speed of 550 to 600 m/min.

Prior to weaving, the weft yarn is wound in a small hollow package called cop which is to be used in shuttle. The conventional cop winding machine is made by Urquahart Lindsay, J F Low, Charles Parker, Britania etc. with the speed of 250 to 1110 rpm. (Fig. 11). Later, Mackie, Schweiter etc. introduced modern automatic cop winding machine in which winding and doffing of the cop are fully automatic and they can run with the speed fr0m 1700 to 3500 rpm.

To prepare the warp yarn, warping and sizing are made to prepare a sheet of yarns, which are wound in a beam called weavers beam. Conventional sizing machines, having 3 to 5 negatively driven steam heated drying cylinders, are manufactured by Urquahart Lindsay, Robertson & Orchar, Lee croll, Angus etc. The delivery speed of these machines is within the range of 20 to 30 m/min. Platt, Zell, Hibbert, Indiquip developed modern automatic sizing machine for jute having 5 to 11 drying cylinder of around 80 cm diameter. The cylinders are positively driven to reduce excessive strain on the warp yarn. Besides, these machines are equipped with automatic control system for moisture in yarn, amount of size material in sow box, yarn breakage stop motion etc. (Fig. 12).

Winding-Machine    Cop-winding-machine    Sizing-Machine

 


Fabric preparation
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In jute industry, old orthodox over-pick shuttle looms are widely used. Looms are non-automatic type for hessian and carpet backing. Looms for sacking are having automatic weft replenishment system, which is called ECCO Loader. But, this equipment often causes cloth defects like miss pick or partially inserted picks. Different shuttleless looms have been developed by different manufacturers. Mackie introduced multiphase type shuttleless loom like Onemach, Twinmack and S-4 with the speed range 160-300 picks/min. Mackie also developed a number of monophase looms with the speed of 200-330 picks/min. Gardella introduced Tegard shuttleless loom for jute which produces two cloths side by side with the speed of about 500 picks/min. Rapier loom ‘ATPR’ and projectile loom STB were incorporated by Russian manufacturer with speed of 180-390 picks/min. (Fig. 13). Circular loom for making jute sacking developed by Rolassis, Saint Freses, FLCB. They are not very successful in Indian Jute Industry due to high end breakage rate. Later, Lohia-Starlinger developed circular loom to weave poly-jute circular fabric having the speed of about 480-520 picks/min. (Fig. 14). Quality fabrics are manufactured on modern looms due to better warp tension & cloth control, stop motions, automatic weft pattering, automatic weft replenishment and electronic control. For small scale cottage industries, handloom attached with dobby and modified for jute weaving has been developed by National Institute of Research on Jute and Allied Fibre Technology, Kolkata.

Rapier-Loom    Circular-Loom

Nonwoven technology is considered to be a forward technology and is one of the promising alternatives very much suited to the jute industry. Nonwoven technology appears to be particularly relevant to the jute industry in view of its high productivity and low wage component of the production cost associated with it. Besides, this offers a means of diversifying into various value-added products which would fetch better returns to the industry using even waste fibres. Today production of jute nonwoven fabric is limited to a few thousand tons of needled felts used mainly for packaging, cushioning, carpet underlaying. Thus much of the jute nonwoven textiles remain untapped. Jute needle punched and adhesive bonded nonwoven products offer cost effective and market oriented diversification for jute.
The high production, automatic nonwoven machines are made by Dilo, Fehrer, Ernest Benz AG etc. (Fig. 15). Fibre control in this machine is very good and hence, products achieve a good quality. The nonwoven fabrics are used as weddings and padding, thermal insulation materials, acoustics insulation, reinforcing material, decorative, household textiles, industrial material, apparels etc.

Needle-Punching-Machine
 


Finishing
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After weaving, the jute fabrics are prepared for packing and despatching. Conventional old machines are mostly used in finishing department of Indian Jute Industry. Followings are the main processes for finishing the jute fabric.
Damping: Damping machine is used to unwind the loom state cloth roll and to add water on the cloth (Fig. 16). Three types of damping machines, viz, nozzle type, brush type and spray type are used with the delivery speed of 170-200 m/min.
Calendaring: It is the process for removal of creases fr0m the cloth under moisture and heat in order to make the surface smooth and lustrous and to improve the cover of the cloth by flattening of yarns. The machine consists of five bowls/rollers fitted vertically, of which middle one is steam roller (Fig. 18). The delivery speed of the machine ranges fr0m 25 to 28 m/min.
Cutting: The cutting machine is used to cut the calendared cloth into pieces of required sizes to manufacture bags or sheets (Fig. 17). Four types of cutting machines are generally used; Rotary cutting machine, Gillotin cutting machine, Scimitar cut and folding machine and Lap cutting machine.
Sewing: It makes a bag of definite shape and size by giving stitches at the open ends of cut fabrics. Four type of stiches, e.g., chain stitch, lock stitch, overhead stitch and heracle stitch are generally used in jute industry, of which chain stitch and heracle stitch with the speed of 1500 stitches/min are most popular. Those machines are manufactured by Robertson Orchar, Union Special corporation, etc. Modern sophisticated sewing machines having 2000 stitches/min for heracle and 2200 stitches/min for hemming are manufactured by Union Special of USA.

Damping-Machine    Cutting-Machine    Calendering-Machine