In the Cotton Mill
The manufacture of cotton cloth may be divided into five departments:
1. Preparatory processes: Opening, carding,
combing, and drawing.
2. Spinning.
3. Spooling, warping, sizing, slashing, entering
or drawing-in.
4. Weaving.
5. Converting and finishing, including bleaching,
mercerizing, dying, printing, and finishing.
Before the cotton fiber can be spun into the yarn from which the cloth is
woven, the bales must be broken open, the impurities removed, and the
fibers arranged so that they are parallel and contain no bunches or
tangles. Care in these processes has become more and more necessary and
important as the demand for a higher quality of cloth, possessing greater
strength and evenness, has been developed. Hence, some of the most
elaborate, complex, and admirable machinery in the mill is that devoted
to these preparatory processes. The principle involved is always that of
thoroughly cleaning the material, then opening it so that every fiber
shall be thoroughly separated from its fellows, and then straightening
out the fibers, no matter what types of machines may be used.
Conveying Fiber
By Air Blast
The heavy laps of cotton are first thrown directly from the bale into the
breaker, and the cotton is then usually blown through large pipes from
the room in which the bales are broken to the room in which the openers
are located.
The functions of the opener are two. The first is to clean from the
cotton the dirt and bits of leaf, pod, and foreign substances, which may
have clung to the fiber as it passed through the gin back on the
plantation. The second is to roll the cotton into a more or less regular
"lap," as it is called.
The Energetic
Opener At Work
As the cotton goes into the opener (see diagram on following page), dusty
and dirty, it is seized by strong teeth fastened upon a large cylinder
(A), revolving rapidly, and is flung by centrifugal force against an iron
grid (B) time after time. Sometimes there is a strong current of air
blowing through the tangled mass, helping to loosen the particles. The
dirt comes out through the grid and is carried away, while the lint
itself, after being carried around an indefinite number of times,
gradually works its way along a channel, and finally out between two
large rollers (C), which compress it once more, so that it is, in effect,
a sheet of batting. This sheet, or lap, is rolled up in a large roll (G),
which may be two or three feet in diameter, and is then ready for the
first doubling or blending process. In mills where strength and evenness
of yarn are at a premium, the sheets from three or four laps may be fed
through another opener, usually called a "scutcher," which breaks them
all apart again, mixes up the fibers, cleans out more of the dirt, and
produces a more even lap.
The cotton, as it comes from the opener and the scutcher, is much cleaner
and more attractive. It begins to look like the riches it contains.
[Illustration: _Cross-section diagram of opener_]
To convey the heavy opener-lap from the opener to the carding room, the
more modern mills are doing away rapidly with hand-power, and carry the
lap on a sort of travelling mono-rail conveyor.
The fibers of the lap which comes from the opening room are by no means
parallel, but lie in all directions just as they happened to come from
the grid of the opener. The function of the card is to straighten them,
and at the same time to remove those which are knotted or immature and of
a length below that required for the yarn to be spun, and to take out
practically all of the impurities which may have escaped in the opening
operations.
The principle of carding is one of the oldest of textile mechanical
principles, and all the improvements that have been made have been in
developments rather than in basic ideas. Hargreaves, inventor of the
jenny, and Sir Richard Arkwright both expended their ingenuity upon it,
the latter seeming to have been the first to provide a carding machine
operated by other than hand-power. The basic principle involved is the
straightening out of the fibers by combing or brushing them with wire
brushes or cards.
[Illustration: _"Scutchers" at work_]
In the revolving flat card, which dominates the field today, there are,
as a rule, three principal cylinders. The lap passes first under the
smallest of the three, called the taker-in, which is covered with very
fine saw-teeth all in one long strip of steel, wound and fixed spirally
in the surface of the cylinder. The taker-in receives the cotton from a
feed-roller (C) that turns above a smooth iron plate (D) called the feed
plate. The saw-teeth comb the fibers which are imbedded, so to speak, in
the lap, and deliver the loose ones to the second cylinder, which is the
largest of the group. This main cylinder is covered with wire teeth all
bent at exactly the same angle. The cotton clings to them, and is carried
around to the top of the cylinder, where it is engaged by teeth on the
revolving-flat card which are bent in the opposite direction. This
"card-clothing" arranged in strip, crosswise on a travelling lattice,
moves in the same direction as the cylinder but moves very slowly, and so
the fibers are carded between the two sets of wire points, the short and
immature fibers remaining on the card wires of the lattice and the
perfect and now almost entirely parallel ones being carried over from the
main cylinder to the doffer cylinder, the third of the trio. From this
they are removed by an oscillating comb (F), coming off in a light,
fleecy lap, which is condensed through a funnel into a soft untwisted
roping, or sliver, about the diameter of a man's thumb, and is then
coiled into a can, usually about 45 inches high by 8 inches diameter.
[Illustration: _View of Modern Motor-Driven Opener Picker_]
The conveying of the sliver (pronounced with a long or short i) into the
can is in itself an exceedingly ingenious operation, although a very
simple one. The device is attached directly to the card, and is called a
coiler. The sliver passes into it from the funnel. The hole from which
the sliver emerges is off the center of a steel plate which revolves
slowly, so that the sliver, as it comes out, has an eccentric motion
which causes it to fall into the can in regular coils. Tangling is thus
prevented, and ease of handling secured.
Combing Necessary in
Spinning Fine "Counts"
Combing is necessary in the preparation of cotton for the spinning of
fine "counts" or coarser yarns where great smoothness and regularity are
desired. They are now quite extensively used in the United States, and it
is significant of the trend of the industry here that the number is
rapidly growing. The first cotton comber was invented by a Frenchman of
Alsace named Heilmann. The patent was issued in 1845. Now there are on
the market other machines, both English and American, similar in
principle but improved in many ways.
[Illustration: _Revolving flat cards_]
The first of these preliminary processes is that which is done by the
sliver-lapper. The slivers from 14 to 20 cans are drawn along
side-by-side, passing between three pairs of drawing rollers which will
be described later. From the drawing rollers the slivers now reduced in
size, pass between two pairs of calendar rollers from which they emerge,
not as a sliver, of course, but once more as a lap about a foot wide.
These laps are usually passed to a ribbon lapper, where six of them are
placed end-to-end, and unrolled simultaneously, passed between four pairs
of drawing rollers, and then superimposed, one upon the other, and,
calendered once more, issued as a lap a little less than a foot wide.
This process may be repeated as many times as the quality of the yarn
desired may require, for each drawing process served to straighten the
fibers and so to render the thread more even and capable of finer
spinning.
Combing is exactly what its name implies. The lap is actually raked by a
fine-tooth comb with needle-like teeth of steel ranging from 16 to 90 per
inch. This involves breaking the lap again and the intricacy of the
comber rests in the mechanism which it employs for joining the separated
ends.
[Illustration: _Cross-section diagram of revolving flat card_]
Six or eight laps go through the machine at once, and the product is
combined, condensed, formed into a continuous sliver, and deposited once
more into cans. The process is not a fast one at best, and the chief
contribution of American inventors is in the direction of speed. Each nip
combs only 4/16 to 4/10 of an inch of fiber. The Heilman machine made
about 85 or 90 nips per minute. The American improvement makes 130 to
135. The width of the lap in the American machine is likewise increased,
and the saving in labor, therefore, is considerable. English improvements
have been in the same direction, the resultant saving being almost as
great.
[Illustration: _Ribbon lappers_]
Though many of the processes already described might be called drawing,
in a sense, insomuch as they involve a continual lengthening and
straightening of the lap or sliver, yet drawing in the strictest sense
has not yet begun. It may be done only once, for coarse and cheap yarn,
or it may be repeated a half dozen or more times to produce the finer and
more expensive products. The frame for each repetition is slightly
different, but several types may be isolated. They are, in the order of
their use, the drawing frame, the fly frame, or slubber, the intermediate
frame, and the roving and jack frames.
For fine counts the slivers from the comber, and for other grades that
which comes directly from the card, are taken, then to the drawing frame.
The slivers from the cans, six or eight in number, are fed through one
aperture, and pass, thus combined, between several (usually four) pairs
of rollers, so arranged that each succeeding pair revolves at a more
rapid rate than that which preceded it. The last pair in the series
revolve probably six or eight times as fast as the first pair. This
combination of rollers pulls constantly on the more or less irregular
slivers, rendering them always more nearly uniform in diameter and
density, the thickness of one of the entering slivers serving to
counterbalance the thinness of the other. The drawing frame consists
usually of four or five "heads," and the sliver, after it passes through
one of these "heads," is put through a second one, along with other
slivers, so that the doubling and redoubling goes on constantly. There is
an electric device to stop the machine when a sliver breaks, either at
the back or the front of the frame.
[Illustration: _Combers at work in a mill spinning fine counts_]
From the last head of the drawing frame, the sliver passes to the fly
frame or slubber, which not only continues the drawing and doubling,
usually between three pairs of rollers, but through the aid of a device
which gives the sliver a slight twist and winds it, for the first time,
upon a spindle. This device is known as the flyer, and is, roughly, a
U-shaped piece of metal, which, revolving, inverted, over the spindle,
gives the thread a slight lateral twist as it coils upon the spindle. The
latter also revolves, but with a diminishing motion so that the amount of
twist may be kept uniform as the diameter of the coil upon the spindle
increases. The sliver, now being twisted, is called a sliver no longer,
but the slubbing.
The slubbing is passed between the rollers in pairs, the emerging product
being less in diameter than the diameter of a single slubbing. The
machine combines the fourfold process of combination, attenuation,
twisting and winding. There are more spindles upon this frame than upon
the slubber.
The last drawing frame, except for very fine yarns spun from Egyptian or
Sea Island staples, is the roving frame, similar in principle to the last
two but containing still more spindles. It receives the rovings from the
intermediate frame, combines two of them into one, twists them a little
more, and winds them upon the spindle tubes. The Jack frame is similar
except that its product is finer and smoother.
[Illustration: _Sliver lappers in a Northern mill_]
It is interesting to note, however, that the majority of improvements
have been the fruit of the brains, not of Americans, but of Englishmen.
Copeland points out that this may be due to the English desire to save in
the consumption of cotton, but that more probably it is due to the
development of fine spinning in England, in which most of the machines
here described are chiefly valuable; and he ventures the prediction that
now that American mills have definitely gone in for the finer counts, it
may be expected that engineers here will apply themselves to the
improvement of this machinery.
[Illustration: _Drawing frames, turning slivers into roving_]
The "Mule" Versus
the Ring Spindle
Spinning is the final process which turns the cotton into firm, coherent
yarn, sufficiently twisted, and ready for the loom. The twist given to
the thread by the previous machines has been only enough to make the
fibers hold together. They are still comparatively loose and fluffy, and
their tensile strength is slight.
There are, in general, two types of spinning machines. The first, the
mule, an English product. The second, radically different, is entirely
American. It was invented in 1828 by James Thorpe, and immediately found
some favor, but it was not until the Civil War that it was received on
equal terms with the mule. Today, however, it dominates in the United
States, the comparative figures in 1917 being: ring spindles 30,264,074;
mule spindles 3,634,761. The disparity is growing greater every year, and
the use of the ring is firmly established in other countries as well. The
figures for 1907 were:
_Mule_ _Ring_
England (1909) 39,800,000 7,900,000
Germany 5,740,000 3,722,000
France 4,122,000 2,481,000
Austria 2,307,000 1,277,000
Italy 1,015,000 1,852,000
Russia 1,031,000 1,320,000
The mule, by reason of the great size to which it has been developed, and
the impressiveness of its large, rhythmic motion, is one of the most
formidable of all cotton machines, as indeed it is one of the most
complex. It received its name from the fact that, performing two
principal functions--drawing and spinning--it was regarded as a hybrid,
just as the mule is a hybrid cross between the horse and the donkey.
In the mule (see diagram on page 53), which is a long and wide machine,
carrying sometimes, in new models, as many as 1,300 spindles, the drawing
and twisting are not continuous but consecutive. The rovings (B) are held
on a creel (A) at the back of the machine, usually in three or four
tiers, or on long beams or spools. They pass from the creel, or spools,
between three pairs of drawing rollers (C.) Coming out of the rollers,
they are fed to the spindles on the carriage which backs away from the
creel and recedes somewhat faster than the rovings are unwound. This
receding is the essential motion of the mule, for thus the cotton
receives its final drawing. The spindles, meanwhile, are revolving
rapidly, spinning the yarn. The twist goes first to the thin places where
the least resistance is offered. Then, as the carriage carrying the
whirling spindles continues to back away, the thicker parts of the
thread, being comparatively untwisted are pulled down to the average
diameter and are twisted in turn. The carriage usually runs back about
sixty-three inches. At the termination of its run, or stretch, the
spindles increase their speed until the twisting is completed and the
carriage starts on its return trip. This reverses the spindles, and the
thread which has been wound upon them is unwound, the slack being taken
up by one guide wire (D) while the other guides the thread to the winding
point, and winds it up in the opposite direction on the cone-shaped cops
on the spindles. The rollers do not feed out more roving as the carriage
returns. Hence, there is no slack when the round trip is completed.
[Illustration: _Slubbers, showing the U-shaped flyers_]
Except for the use of drawing rollers, there is little similarity between
the mule and the ring frame. The latter has no movable carriage, none of
the splendid sweep of motion that makes the mule so fascinating to
watch. The ring-frame is simple and business-like, and its speed is
amazing. The bobbins holding the roving are placed directly over the
spindles. Around each of the latter is a steel ring. There are at least
112 spindles on each machine, and all the machine rings for the spindles
are fixed in a single frame. The upper edge of the ring is flanged, like
a miniature railroad track, and snapped over the flange is a small but
important C-shaped steel ring, called the traveler.
How Thread is Spun
on the Ring Spindle
When the machine is in operation (See diagram on page 56) each roving (H)
leaving its bobbin, runs through the usual drawing rollers (G) then
through a guiding wire to the ring, where it is passed through its
traveler (B) which is always at the winding point on the spindle. As the
spindle and the rollers revolve, the roving is fed out at a considerably
slower rate than the spindle takes it up, so that there is always a
tension on the thread. The whirling spindle thus pulls on the traveler,
drawing it round and round on its flanged track (A). It revolves just a
little more slowly than the spindle and thus the yarn receives its twist.
Meanwhile, the frame (C) on which the rings are fixed moves slowly up and
down, so that the winding is properly regulated.
It is possible to operate the spindles at a remarkable speed. So perfect
are the bearings which have been evolved that the average speed is ten
thousand revolutions a minute, and on fine yarns it is sometimes 12,000
to 13,000 revolutions. The speed is limited by only two factors: the
first is the ability of the operator to make splicings when threads
break, and the second is the tendency of the traveler to fly off when the
speed is too high. The number of travelers consumed is high at best, and
in a mill which has long been in operation the floor in the front of the
frame is likely to be paved with the little steel rings which have fallen
and been ground into the planks by the heels of the worker.
[Illustration: _Diagram of mule_]
The battle between the advocates of the ring frame and those who favor
the mule is still on. For the American spinner the ring has undoubtedly
many advantages. Because it spins continuously, and not intermittently,
it turns out about a third more yarn per operator. It is usually
admitted, however, that the thread from the mule is more even in
diameter. Advocates of the mule say, moreover, that the thread from the
mule is softer and "loftier", and that cloth woven from it has a more
"clothy" feel. But others say they can produce soft yarn with the ring.
In the United States, where the labor cost is a vital item, the
ring-spindle has an assured place.
[Illustration: _Mules at work_]
The yarn is now a finished product. It may be sold by the spinner to the
weaver or it may be woven in the mill in which it is spun. Before it is
ready for the loom, however, there are a number of operations which must
be completed.
The yarn from the ring frame, or mule, is wound in a large cop, or on a
bobbin. It must be put upon spools before it can be warped. The spooler
is a simple machine, but one that requires constant attendance. In the
spooler, bobbins are placed upon holders or spindles, and the thread is
passed over a series of guides to the spool, up above. The spool revolves
at a high rate of speed, and the thread is wound evenly upon it. The
operator must watch for broken threads, retie them, replace the empty
bobbins by full ones and see that the empty ones are gathered up
uninjured. She--the operator is usually a girl or woman--must be alert
and active, and especially nimble fingered.
[Illustration: _"Close-up" of Ring Spindle in American mill_]
One of the most important inventions, one that was received with acclaim
by the American manufacturer, and one which actually reduced his labor
cost on spooling no less than ten per cent. at one clip, is a tiny little
thing that is held in the palm of the hand. This is the Barber knotter.
When a thread breaks, the attendant places the two ends together in the
machine and by the mere pressure of her thumb ties the knot much better
than she could do it without the knotter. The economies which it effects
extend beyond the mere spooling, for better knots mean fewer breaks in
the warping process, and a better cloth at the end of weaving.
The spools from the spooler are placed on a large frame, called a creel.
The creels have an average capacity of about 600 spools, and there are
usually 16 to 20 in one tier. The threads from the spools are drawn
between the dents of an adjustable reed, then under and over a series of
rollers. From here they are led down to the beam, upon which they are
wound. The revolving of the beam unwinds the yarn from the spools and
winds it regularly and evenly upon the beam itself. There is a device for
measuring the length of the warp wound, and stop motions for arresting
the operation should a thread break or other accident occur.
[Illustration: _Each operator at these spoolers has a Barber knotter on
her hand_]
The yarn of the warp must usually be impregnated with a sizing which will
smooth out and stick down its furry surface and add as well to the
tensile strength so that the strain of weaving may be withstood. For this
the most effective and most generally used machine is the slasher, the
chief feature of which is a roller, whose lower side is immersed in the
sizing solution. Threads from the warp beam are run around this roller
through the solution and then dried, after which it is finally wound on
another beam for the loom. A considerable number of loom beams can be
filled from one set of the warper beams mounted in the slasher.
The lengthwise threads of a fabric are called the warp. The crosswise
threads are called the weft or filling. To make cloth, the warp and weft
must be interlaced with each other in a suitable manner. The operation is
called weaving, the machine in which it is performed is, of course, the
loom. The principal operations of weaving are as follows:
1. Shedding, or the raising and lowering of the alternate threads
of the warp, so that the weft may pass under and over them.
This is done by means of the harnesses and their heddles.
2. Picking, or placing a thread of the weft between the warp
threads so raised and lowered by means of the shuttle.
3. Beating-up, or pushing, each thread of the weft into its
position close against the thread which has preceded it by
means of the reed.
4. Letting-off, or permitting the warp to unwind from the beam only
just as fast as is needed by the speed of the weaving. This is
accomplished by friction bands and weights on the warp beam.
5. Taking-up, or winding upon a roller the cloth as it is
manufactured.
In addition to these primary operations, the loom has attachments for
performing several other functions, such as stop-motions for stopping the
loom when warp or filling threads break, or when the shuttle fails to
cross the loom completely; temples for holding out the cloth laterally as
the weaving proceeds; a mechanism--in the most modern looms--for changing
the shuttles, or the cops in the shuttles, as the weft thread on the cops
becomes exhausted, etc.
[Illustration: _Diagram of ring spindle_]
The modern cotton loom, which automatically removes the filling bobbins
without stopping the loom, is rapidly displacing the older types, and one
weaver can now attend to a surprisingly large number of looms, being
greatly assisted also by the automatic warp and filling "stop motions."