REELING / SPINNING OF SILK YARN

INTRODUCTION:

Silkworms’ are reared for the sole purpose of obtaining cocoons which form the raw material for producing raw silk. It was discovered several millenniums ago that the cocoons of the silk­worm could be softened in hot water and the continuous silk filaments could be drawn there from to produce well united and strong, threads uniform thickness for the manufacture of beautiful and durable fabrics.

Rearing of silkworms for the production of cocoons constitutes sericulture, while reeling, is concerned with unwinding, of the silk filaments of the cocoons through suitable techniques to form a composite thread fit for weaving.

Reeling:

Raw silk having certain specifications is obtained by adopting any one of the two methods of reeling popularly known as (i) direct reeling method on standard reels and (ii) re‑reeling method which includes preliminary reeling on small sized reels and transferring the reeled silk directly from the reels to standard sized reels on re‑reeling machines.

The temperature of water in the reeling machines should be kept at optimum levels suited to the type of appliance used, nature of water and condition of the cocoons at the time of reeling to keep the reeling at high operational level. The cooked and brushed cocoons with their filaments cleared are put into the reeling basin and transferred to the reeler. The ends of the released clear baves are tied to a hook provided on the reel bench near the basin.

Formation of the reeling end: A required number of baves from as many cocoons according to the size of raw silk thread to be reeled are combined and passed upwards through the guide‑eye of a threader, which is either a porcelain button or a jettebout with the object of primary grouping of the several haves drawn and combined to form the required composite thread. The group of baves emerging from the threader is then passed over a device con­sisting of two or three small wheels or pulleys so placed to intertwine the thread in a large number of spirals before it is finally passed through another guide eye of a dis­tributor mechanism attached to the reel.

Jettebout: The most important and skilled work of the reeler, apart from proper preparation of the cocoons, consists in attaching fresh filaments as required promptly to the silk thread under reeling in order to maintain regularity of size and continuity of thread. Furthermore, any carelessness in taking the correct length of filament on the finger for casting causes several types of defects in the raw silk. "Casting" technique puts a limitation on the number of ends a reeler can manage because of the low rate of casting in manual operation. With the object of overcoming the deficiencies of this technique and to facilitate prompt attachment of filaments, the modern basins are provided with the device known as a jettebout.

Croissure: Croissure is a mechanism of intertwining or crossing of two threads by twisting the threads in a series of spirals during its passage from the threader to the reel. The primary effect of the croissure is to knead the group of filaments passing through the spirals to form a round, smooth and compact thread firmly cemented or aggluti­nated with an even coating of sericin.

Reels: The silk thread after leaving the croissure is wound in a series of superimposed coils on the reel. The important functions of the reel are firstly to draw off the baves from the cluster of cocoons in the end and help in the formation of a continuous thread.

Small reel: The small reels of the multi‑end machines have six ribs, usually made of wood and spaced at an angle of 60⁰, but these are held on solid single arms or on the periphery of metallic discs of special design.

Speed of reels: The production of reeled silk as well as its quality is largely controlled by the length of thread that is produced in a unit time. This depends upon the perimeter of the reel and its velocity. But the speed of the reel or rate of thread production should be carefully adjusted taking into consideration reliability of cocoons and the non‑breakable filament length of the cocoon.

Traverse or Distributor: The silk even after leaving the croissure still contains a considerable quantity of water and the sericin is soft and remains wet and sticky. When silk in this condition is wound on the reel the defects of ribbing and plastering easily occur.

Grant reeling: In this system each reel operates its own traverse mechanism consisting of a set of gears having specific ratios between them to obtain the particular pattern and number of webs or diamonds across the face‑of the hank as prescribed for the International standard hank. For instance in a combination of 13:24 gear ratio, for every 24 revolutions of the reel, the traverse crank or eccentric makes only 13 revolutions thus moving the connected traverse rod forward and backward 13 times producing thereby 13 diamonds or webs across the face of the hank ' as specified by International standards. This grant reeling technique is adopted in direct reeling as in the re‑reeling machines.

Re‑reeling:

Direct‑reeled silk, in spite of all the care taken in reeling, contains certain defects such as short lengths of fine sizes, broken threads, entanglements, hard gum spots, short lengths of loose threads, etc. These defects cannot be removed or rectified by repairs in the process of silk examination. These defects lead to poor winding and increased wastage of material, and consume more time and labor in the subsequent processes of silk throwing and twisting operations. The defects of direct‑reeled silk axe removed by a process of re-­reeling of the silk already reeled on to standard reels of a re‑reeling machine.

Silk Examination, Lacing and Skeining:

The raw silk hank from the re‑reeling machine is taken to the silk examination room for conducting visual examination of the silk and for preparing the silk hank for skeining and packing. Silk examination is generally done in a specially constructed rectangular hall running east to west and having sky lights of special ground glass windows on the northern side in order to obtain good diffused light.

Lacing consists of passing a thread across the skein in such a way as to divide it into five equal parts with the purpose of keeping the threads in place to ensure the thread being unwound easily.

The cleaned and laced hanks are then skeined by a separate set of operatives. Skeining is done by twisting the hank several times and folding the hank upon itself in a number of spirals in such a manner that the silk threads in the hank are not ruffled or entangled in the subsequent processes of booking and bundling, and general handling of the silk until it is opened for use in the twisting and throwing operations.

Booking: The skeins are made into neat books of approximately equal weight and dimensions in a book‑making machine. In a book there are eight skeins in the horizontal row and five in the vertical row. Each book is neatly tied with separate cotton bands at three different places and wrapped in tissue paper. The books are then carefully wrapped in thin cotton material first and then wrapped in Hessian cloth and packed into a bale of approximately 133 lb or 60 kg.

Recovery of Silk: The total weight of raw silk that can be produced from any lot is primarily determined not by the gross weight of silk in the cocoons but by the actual quantity of silk that can be recovered from it in reeling or inversely, by the total quantity of silken wastes present in the bulk lot.

Silk waste: All the cocoons included in the bulk lot may not be reelable and the unreelable cocoons form the first type of the 'waste' in the bulk lot. The next waste is the unreelable portion or the silk shell like the floss and the pelade layers.

By‑products of Reeling:

The chief by‑products of the reeling industry are mainly the silk wastes obtained at different stages of processing cocoons into raw silk and the pupae. These are valuable material giving substantial returns to the reelers by their sale. All the waste obtained in the course of reeling may be classified as follows:

(i) cocoon wastes (ii) reeling wastes (iii) winding wastes

Pupae: The Silkworm pupae are very rich in protein and fat contents. They are used as manures and feed for cattle, fish and poultry. In many sericultural countries oil is also extracted from pupae by expression or by solvent extraction.

Anciliary Equipment:

Boiler: Steam is used in the filatures essentially for heating water in the cooking and reeling basins and for stifling the cocoons. Ordinarily a total of 100 lb of steam at 75 lb per =2 pressure would be required for every installed basin. The size of the boiler would, therefore, depend upon the installed capacity of the filatures.

Power: Electricity is undoubtedly the best motive power, although manual labor is also popular in the cottage sector. Each unit of twenty reeling basins made up of ten basins in each row should be supplied with an independent low horsepower (2 H.P.) motor.

Re‑reeling machine: Ordinarily the ratio between reeling and re‑reeling machines, when re‑reeling is done from small reels, is one reel for every fifty ends; whereas it is one reel for every ten ends for re‑reeling direct‑reeled silk mounted an swifts.

Eprouvettes and Denier Scales: With the increasing demand for raw silk of uniform sizes the need for maintaining accuracy of the size of silk reeled has become a necessity. This is done by taking test wrappings from reels at random intervals when reeling is in progress, by using eprouvettes and denier scales.

Silk examination stands: These are simple‑ wooden racks for stretching the silk hank for examination, cleaning and lacing before skeining.

Silk skeining machines: This simple small‑sized hand‑operated equipment is generally fixed to the work table. Ordinarily 300‑350 skeins can be made in one day with one skeining machine and one operative.

Booking presses: These small, simple presses are required for binding a certain number of skeins to make a weight of 2 kg. With one booking press 60 to 70 books can be made in one day.

Testing appliances: A modern filature requires certain standard raw silk testing appliances. Firstly these help in maintaining effective control on the quality of raw silk during produc­tion and secondly enable the filatures to sort the product into qualities and grades before marketing.

Workshop: It is essential for every filature to have a workshop with necessary equipment to deal with day‑to‑day repairs in the factory as well as for manufacture of simple light parts of the several machines and equipment used in the filatures.

Laboratory: The role of a scientific laboratory in a filature organization can not be over­stressed. It is a must for every filature. The laboratory need not be very large, but it must be sufficiently well‑equipped to tackle the various problems which frequently arise in the functioning of the filatures.

Other ancillaries: These include cocoon racks, cocoon trays, baskets, floor mats, cocoon trolleys, buckets and platform scales for weighing cocoons, etc.

Water Dampness: Water plays a very important role in the reeling industry. Water is directly used for cooking cocoons, as medium for reeling and preparation of byproducts such as silk wastes obtained in reeling.

Mill Damp: This refers to the humid mist which forms in a mill when the steam in the air condenses. The air in a filature inevitably becomes highly laden with the moisture rising from the various basins and the material immersed in them. The frequency with which saturation point is reached must be considerable, since at 22 0 C it requires only 20 gm of moisture per cubic meter or about 2‑5 per cant of its volume for the atmosphere to reach that point.

SYSTEMS OF REELING:

The evolution of the reeling machines and the methods of reeling are briefly described below:

Dotorikikai: In ancient times a crude contraption known as dotorikikai was used for reeling in Japan. It consisted of a cylindrical piece of light wood about 12‑5 cm in diameter and 60 cm in length. This was fixed on an extended axis loosely held at either ends of supports about 15 cm high.

Tegurikikai: Later an improved model called "Tegurikikail' was used until about the middle of the last century. It consisted of a rectangular reel 75 am in circumference with an extended axle resting loosely on upright supports. One end of the axle was provided with a bamboo handle for turning the reel.

Zagurikikai: This sedentary type reeling equipment was introduced later. The circumference of the reel in this equipment was about 53 cm with four reel bars.

Ashibumikikai: Zagurikikai was followed by modified reeling equipment modeled after the foot‑reeling machine originally imported from Europe. It was simple in construction with considerable improvement over the equipment previously described. It consisted of a reeling table and a separate frame for holding the reel.

Hand‑reeling Machinery of Japan: As long as the preparation of filaments and casting of ends to keep the silk thread con­tinue to remain manual operations, the process is known as hand‑reeling as against machine reeling. Although the reels are driven by power and water is heated by steam, the reeling is still hand‑reeling because the filament casting is dependent on the skill of the hand only.

Direct Reeling Machine: The direct‑reeling machine designed for reeling a silk hank of 150 cm circumference, in conformity with International standards, was largely popular in Europe. The silk reeled by this method can be directly used for winding operations which is the first operation in the conversion of raw silk into twisted silk yarn.

Country Charka: The country charka is a manual‑powered reeling machine extensively used in the cottage reeling sector of the Indian reeling industry. It is entirely home built by the owner with material available locally in the village and with the help of the village carpenter and blacksmith. Generally each charka establishment installs five to six charkas and each charka consists of three distinct parts, namely the mud platform, distributor and reel.

Mud platform: This is rectangular in shape usually measuring about 60 to 75 cm high x 90 cm side and 120 cm long. The forepart has a built‑in fireplace with a basin fitted over it. The other part of the platform is solid with a flat top intended for the reeler to sit and attend to the reeling operations.

Distributor: This is a simple device consisting of a crudely made eccentric wheel which in operation revolves on its vertical axis and drives the wooden traverse rod back­wards and forwards. The traverse rod is aligned parallel to the front side of the platform and stands about 20 to 25 cm above.

The reel: Only one long reel made of thick sections of seasoned wood is provided for each basin. Its c1rcumference is under standardized and ranges from 150 cm to 225 cm in different charkas although the popular circumference is 200 cm.

Domestic Machine: The domestic machine was evolved in Mysore State sometime between 1925 ‑ 1927 to make better and more economic use of the steadily improving qualities of reeling cocoons. It is an assembly of three separates but functionally connected parts namely the cooking unit, the reel bench and the reel box.

Cooking unit: The cooking unit consists of a masonry structure of a convenient height in which several ‑ usually four ‑ cooking basins are fixed in a row. The basins are generally double pan type similar in design to the cooking basins used in filature reeling machines.

The reel bench: It is a simplified basin from the original European design and its size is restricted to actual requirements. Generally each unit consists of four to five reeling basins.

The reel frame: This is an angle‑iron or wooden frame fitted about one meter away from and parallel to the reel bench. The height of the reel bench is generally kept at about 150 to 170 cm from the ground.

Cottage Machine: In the post war period, the domestic machine was followed, in keeping with the general trend of development of the reeling industry, by an improved machine popularly known as a Cottage machine patterned on the lines of the Japanese multi‑end machine imported in 1951 by the Central Silk Board for experimentation.

Multi‑end Reeling Machine: The multi‑end reeling machine came into industrial use about eighty years ago. It was evolved in Japan to make better and more economic use of the superior quality of reeling cocoons produced by the country's sericulture industry as a result of the application of the results of research in moriculture and silkworm rearing.