Manufacture Of Cotton Yarn





=Picker Room.= The first step in the conversion of the bale of cotton

into yarn consists in giving the cotton fibers a thorough cleaning.

This is accomplished by feeding the cotton to a series of picker

machines called in order, bale breaker, cotton opener and automatic

feeder, breaker picker, intermediate picker, and finisher picker.

These machines pull to shreds the matted locks and wads of cotton (as

we find them in the bale), beat out the dirt, stones, and seeds, and

finally leave the cotton in the form of batting upon the cylinders;

this batting passes from one machine to another until it issues from

the finisher picker as a downy roll or lap.



(Sometimes the bale breaker is not used in the mill.)



=Carding Machine.= When the lap of cotton leaves the picker it goes to

the carding machine, where it is combed into parallel fibers by means

of a revolving cylinder covered with wire teeth called card clothing.

As the cotton is fed to the card in the form of a sheet or lap from

the picker, it is supposed to have been freed from a considerable

quantity of sand, seed, etc., but there still remain nep, fine leaf,

and short fibers, which are removed during carding.



On leaving the card cylinder the lap has become a gossamer-like web

thirty-nine inches broad. This web next passes through small "eyes,"

which condense it into a narrow band about an inch in width, known as

card sliver.



When a lap is delivered from the finisher picker, it should weigh a

given number of ounces per yard. The method of ascertaining the weight

is to make each lap a standard number of yards in length and weigh

each lap. The machine can be regulated so as to give the desired

weight per yard.



=Combing.= When an extremely fine and strong yarn is required, in

addition to carding, the fibers are also subjected to the process of

"combing." This may be said to be merely a continuation of the carding

process to a more perfect degree. The chief object is to extract all

fibers below a certain required length, and cast them aside as

"waste." This is done in order to secure the very best fibers

calculated to give the strongest and best results in the spun yarn.



The process of combing follows carding. The card delivers the cotton

in the form of a sliver or strand, while the combing machine requires

the fibers to be delivered to it in the form of sheets, nine to twelve

inches wide. This is done by taking a number of card slivers and

forming a lap of them by passing the sliver through a sliver lap

machine. The laps are passed through the comber. This machine consists

essentially of a series of rollers, nippers, and rows of metal teeth.

By the action of these, the short fibers are separated and combed out,

and the long ones arranged in parallel order in the form of a thin,

silky strand, in which condition it is sent to the drawing frames to

be drawn out. Of course it must be understood that a combing machine

is used by only a small percentage of cotton spinners. For ordinary

purposes a sufficiently good quality can be made without a comber. As

there is from 15 to 35 per cent waste to this operation it may be

readily seen that it is costly, and limited entirely to the production

of the very best and finest yarns, such as those intended for sewing

or machine thread, fine hosiery, lace curtains, underwear, imitation

silks, and fine grades of white goods. There are combing machines that

comb short staple cotton.



=Drawing.= The cans containing the slivers are taken from the card or

combing machine (as the case may be) to the drawing frame. The object

of this machine is mainly to equalize the slivers, combining a number

of them together so as to distribute the fibers uniformly. The

condition of the fibers on leaving the card or comb is such that a

slight pull will lay them perfectly straight or parallel, and this

pull is given by the drawing frame rollers. Of course the fibers

coming from the comb are parallel, but it is necessary to alternate

them by the drawing. The drawing frame is a machine consisting of a

number of sets of rollers, the front roller having a greater speed

than the rear ones.



The slivers, which are as nearly as possible the same weight per

yard, are combined together in the drawing and emerge from the pair of

front rollers as one sliver weighing the same number of grains per

yard as a single sliver fed up at the back. This process is repeated

two or three times, according to requirements, the material then being

referred to as having passed through so many "heads" of drawing. It is

not unusual to pass Indian and American cotton through three

deliveries.



The object of all the processes thus far described has been that of

cleaning (in the picker), arranging the fibers in a parallel position

to each other, making uniform, and drawing out the stock. In every

case the stock delivered from a machine is lighter than when fed into

it, and contains just twist enough to hold it together and prevent its

being stretched or strained when unwound from the bobbin, and fed into

the next machine. The minimum amount of twist in roving is desirable

for the reason that it permits the stock to be drawn out more easily

and uniformly, the little twist that is put in the roving by the

slubber being practically eliminated when it is passed through the

rolls of the intermediate. The same applies in the case of the roving

passing from the roving to the spinning frame.



=Fly Frames.= The process in the manufacture of yarn after the cotton

has passed through the drawing frame consists of further attenuation

of the sliver, but as the cotton sliver has been drawn out as much as

is possible without breakage, a small amount of "twist" is introduced

to allow of the continued drawing out of the sliver.



From the drawing frame, the drawing passes through two, three, or four

fly frames, according to the number of yarn to be made. All these

machines are identical in principle and construction, and differ only

in the size of some of the working parts. They are the slubber,

intermediate, roving,--and fine or jack frame-fine, and the function

of each is to draw and twist.



=Intermediate Frame.= The function of the intermediate frame is to

receive the slightly twisted rove from the slubber and add thereto a

little more twist and draft. The rove is taken from two bobbins to

one spindle in the machine, an arrangement which tends to insure

strength and uniformity. The principle of the machine is in other

respects the same as that of the slubbing frame.



=Roving Frame.= The function of the roving frame is to receive the

twisted rove from the intermediate and add more twist and draft,

thereby further attenuating the rove. As in the intermediate frame the

rove is generally taken from two bobbins for one spindle.



=Fine or Jack Frame.= This machine is used when fine yarns have to be

made. It is built on the same principle as the preceding frames, the

only difference being that a finer rove is made from which finer

numbers of yarn can be spun. As in the slubber, intermediate, and

roving frames, the rove is taken from two bobbins for one spindle.



=Spinning.= In the manufacture of single ply yarn the final process is

that of spinning, which consists in drawing out the cotton roving to

the required size, and giving it the proper amount of twist necessary

to make the yarn of the required strength. While the spinning frame is

built on entirely different principles from the roving, intermediate,

or slubber frame, the object of each machine is the same as that of

the spinning frame. The principal point of difference is the amount of

twist imparted to the cotton roving.



The objects of the spinning process are:



1. Completion of the drawing out of the cotton roving to the required

size.



2. Insertion of the proper amount of twist to give the thread

produced strength.



Excessive speed causes defects in the yarn and undue wear and tear on

the machine.



There are two methods of spinning: ring spinning and mule spinning.

The mule spinning is the older form. There are but few mule frames in

operation in this country.



=Mule Spinning.= The function of mule spinning is to spin on the bare

spindle, or upon the short paper tubes, when such are required to form

a base for the cop bottom. The mule will spin any counts of yarn

required, and is especially adapted for yarn in which elasticity and

"cover" are essentials. Hosiery yarns are produced on the ordinary

cotton mule and are very soft spun.



The bobbins of roving are placed in a creel at the back of the

machine, the stands of roving being passed through the rolls and drawn

out in the same manner as at the roving frame. The spindles are

mounted on a carriage which moves backward and forward in its relation

to the rolls, the distance roved being about five feet. When the

spindles are moving away from the frame the stock is being delivered

by the rolls, the speed at which the spindles move away from the rolls

being just enough to keep the ends at a slight tension. The twist is

put in the yarn at the same time.



When the spindles reach their greatest distance from the rolls, the

latter are automatically stopped and the direction of the motion of

the spindle carriage reversed. The yarn is wound on the spindle while

the carriage is being moved back toward the rolls, the motion of the

rolls being stopped in the meanwhile, the spindles revolving only fast

enough to wind up the thread that has been spun during the outward

move of the carriage.



The mule is a much more complicated machine than the ring frame, its

floor space is much greater, and more skilled help is required for its

operation. Under ordinary conditions it is not practical to spin finer

yarn than No. 60s on a ring, while as high as No. 500s is said to have

been spun on a mule. The same number of yarn can be spun on a mule

with less twist than on the ring. This is important in hosiery yarn.



Ring spinning is used for coarse numbers, and has greater production

and requires less labor than mule spinning. Ring-spinning yarn is used

for warp purposes.



=Ring Spinning.= The function of ring spinning is to draw out the rove

and spin it into yarn on a continuous system. The yarn made is spun

upon bobbins.



The ring spinning differs from mule spinning in having the carriage

replaced by a ring, from which the machine takes its name. The ring is

from one and one-half to three inches in diameter, grooved inside and

out, and is connected with a flat steel wire shaped like the letter D,

called the "traveller." Its office is to constitute a drag upon the

yarn, by means of which the latter is wound upon a bobbin. Its size

and weight depend on the counts of yarns to be spun; coarse yarns

demand the largest ring and heaviest traveller.





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