_Breaker and Finisher Cards_. After the fibre from the softening
machine has been conditioned for the desired time, it is ready for
one of the most important processes in the cycle of jute manufacture;
this process is termed carding, and is conducted in two distinct
types of machines--
1. The breaker card.
2. The finisher card.
The functions of the two machines are almost identical; indeed, one
might say that the work of carding should be looked upon as one
continuous operation.
The main difference between the two types of machines is in the
method of feeding, and the degree of fineness or setting of the
small tools or pins which perform the work. In both cases the action
on the stricks of jute is equivalent to a combined combing and
splitting movement, and the pins in the various rollers move
relatively to each other so that while the pins of a slowly-moving
roller allow the strick or stricks (because there are several side
by side) to pass slowly and gradually from end to end, the pins of
another but quickly-moving roller perform the splitting and the
combing of the fibre. The pins of the slowly-moving roller hold, so
to speak, the strick, while the pins of the quickly-moving roller
comb out the fibres and split adhering parts asunder so as to make a
comparatively fine division.
The conditioned stricks from the softening machine are first
arranged in some suitable receptacle and within easy reach of the
operative at the back or feed side of the breaker card. A receptacle,
very similar to that used at the breaker card, appears near the far
end of the softening machine in Fig. 13.
A modern breaker card is illustrated in Fig. 14. The feed or back of
the card is on the extreme right, the delivery or front of the card
on the extreme left, while the gear side of the card is facing the
observer. The protecting cages were removed so that the wheels would
be seen as clearly as possible.
Some of the stricks of fibre are seen distinctly on the feed side of
the figure; they are accommodated, as mentioned, in a channel-shaped
stand on the far side of the inclined feed sheet, or feed cloth,
which leads up to and conveys the stricks into the grip of the
feeding apparatus. This particular type is termed a "shell" feed
because the upper contour of the guiding feed bracket is shaped
somewhat like a shell. There is a gradually decreasing and
suitably-sized gap between the upper part of the shell and the pins
of the feed roller.
The root ends of the pins in this roller lead, and the stricks of
fibre are gripped between the pins and the shell, and simultaneously
carried into the machine where they come into contact with the
points of the pins in the rapidly-revolving large roller, termed a
cylinder. The above-mentioned combing and splitting action takes
place at this point as well as for a distance of, say, 24 inches to
30 inches below. The fibres which are separated at this stage are
carried a little further round until they come into contact with the
points of the pins in the above-mentioned slowly-moving roller,
termed a "worker," and while the fibres are moving slowly forward
under the restraining influence of the worker, they are further
combed and split. A portion of the fibres is carried round by the
pins of the worker from which such fibres are removed by the
quicker moving pins of the second roller of the pair, termed a
"stripper," and in turn these fibres are removed from the pins of
the stripper by the much quicker moving pins of the cylinder.
[Illustration: FIG. 14 MODERN BREAKER CARD]
The above operations conducted by the first pair of rollers (worker
and stripper) in conjunction with the cylinder, are repeated by a
second and similar pair of rollers (worker and stripper), and ultimately
the thin sheet of combed and split fibres comes into contact with the
pins of the doffer from which it is removed by the drawing and pressing
rollers. The sheet of fibres finally emerges from these rollers into
the broad and upper part of the conductor. This conductor, made mostly
of tin and V-shaped, is shown clearly on the left of the machine in
Fig. 14. Immediately the thin film or sheet of fibres enters the
conductor, it is caused as a body gradually to contract in width and,
of course, to increase in thickness, and is simultaneously guided and
delivered to the delivery rollers, and from these to the sliver can,
distinctly seen immediately below the delivery rollers. The sliver is
seen emerging from the above rollers and entering the sliver can.
The fibres in this machine are thus combed, split and drawn forward
relatively to each other, in addition to being arranged more or less
parallel to each other. The technical term "draft" is used to
indicate the operation of causing the fibres to slip on each other,
and in future we shall speak about this attenuation or drawing out
of the fibres by this special term "draft."
It will be evident that, since the sliver is delivered into the can
at the rate of about 50 yards per minute, this constant flow will
soon provide a sufficient length of sliver to fill a sliver can,
although the latter may hold approximately 20 lbs. The machine must,
of course, deliver its quota to enable succeeding machines to be
kept in practically constant work. As a matter of fact, the machines
are arranged in what are termed "systems," so that this desirable
condition of a constant and sufficient feed to all may be
satisfactorily fulfilled.
The driving or pulley side of the breaker card is very similar to
that shown in Fig. 15 which, however, actually represents the pulley
side of one type of finisher card as made by Messrs. Douglas Fraser &
Sons, Ltd., Arbroath. All finisher cards are fed by slivers which
have been made as explained in connection with the breaker card, but
there are two distinct methods of feeding the slivers, or rather of
arranging the slivers at the feed side. In both cases, however, the
full width of the card is fed by slivers laid side by side, with,
however, a thin guide plate between each pair, and one at each
extreme end.
One very common method of feeding is to place 10 or 12 full sliver
cans--which have been prepared at the breaker card--on the floor and
to the right of the machine illustrated in Fig. 15. The sliver from
each can is then placed into the corresponding sliver guide, and
thus the full width of the machine is occupied. The slivers are
guided by the sliver guides on to an endless cloth or "feed sheet"
which, in turn, conveys them continuously between the feed rollers.
The feed apparatus in such machines is invariably of the roller type,
and sometimes it involves what is known as a "porcupine" roller. It
will be understood that the feeding of level slivers is a different
problem from that which necessitates the feeding of comparatively
uneven stricks.
[Illustration: By permission of Messrs. Douglas Fraser & Sons, Ltd.
FIG. 15 FINISHER CARD WITH DRAWING-HEAD]
The slivers travel horizontally with the feed-sheet and enter the
machine at a height of about 4 feet from the floor. They thus form,
as it were, a sheet of fibrous material at the entrance, and this
sheet of fibres comes in contact with the pins of the various pairs
of rollers, the cylinder, and the doffer, in much the same way as
already described in connection with the breaker card. There are,
however, more pairs of rollers in the finisher card than there are
in the breaker card, for while the latter is provided with two pairs
of rollers, the former may be arranged with 3, 4, 5 or even 6 pairs
of rollers (6 workers and 6 strippers). The number of pairs of
rollers depends upon the degree of work required, and upon the
opinions of the various managers.
There are two distinct types of finisher cards, viz--
1. Half-circular finisher cards.
2. Full-circular finisher cards.
The machine illustrated in Fig. 15 is of the latter type, and such
machines are so-called because the various pairs of rollers are so
disposed around the cylinder that they occupy almost a complete
circle, and the fibre under treatment must move from pair to pair to
undergo the combing and splitting action before coming into contact
with the doffer. There are five pairs of rollers in the machine in
Fig. 15, and all the rollers are securely boxed in, and the wheels
fenced. The arrangement of the wheels on the gear side is very
similar to that shown in connection with the breaker card in Fig. 14,
and therefore requires no further mention. Outside the boxing comes
the covers, shown clearly at the back of the machine in Fig. 15, and
adapted to be easily and quickly opened when it is desired to
examine the rollers and other parts.
The slivers, after having passed amongst the pins of the various
rollers, and been subjected to the required degree of draft, are
ultimately doffed as a thin film of fibres from the pins of the
cylinder and pass between the drawing rollers to the conductor. The
conductor of a finisher card is made in two widths, so that half the
width of the film enters one section and the other half enters the
other section. These two parallel sheets, split from one common sheet,
traverse the two conductors and are ultimately delivered as two
slivers about 6 inches above the point or plane in which the 10 or 12
slivers entered, and on to what is termed a "sliver plate." The two
slivers are then guided by horns projecting from the upper surface
of the sliver plate, made to travel at right angles to the direction
of delivery from the mouths of the conductors, and then united to
pass as a single sliver between a pair of delivery rollers on the
left of the feed and delivery side and finally into a sliver can.
In special types of finishing cards, an extra piece of
mechanism--termed a draw-head--is employed. The machine illustrated
in Fig. 15 is provided with this extra mechanism which is supported
by the small supplementary frame on the extreme right. This special
mechanism is termed a "Patent Push Bar Drawing Head," and the
function which it performs will be described shortly; in the
meantime it is sufficient to say that it is used only when the
slivers from the finisher card require extra or special treatment. A
very desirable condition in connection with the combination of a
finisher card and a draw-head is that the two distinct parts should
work in unison. In the machine under consideration, the feed and
delivery rollers of the card stop simultaneously with the stoppage
of the draw-head mechanism.
One of the chief aims in spinning is that of producing a uniform
thread; uniform not only in section, but in all other respects. A
so-called level thread refers, in general, to a uniform diameter,
but there are other equally, if not more, important phases connected
with the full sense of the word uniform.
It has already been stated that in the batching department various
qualities of jute are mixed as judiciously as possible in order to
obtain a satisfactory mixture. Fibres of different grades and marks
vary in strength, colour, cleanness, diameter, length and suppleness;
it is of the utmost importance that these fibres of diverse
qualities should be distributed as early as possible in the process
so as to facilitate the subsequent operations.
[Illustration: _By permission of Messrs. James F. Low & Co., Ltd. _
FIG. 16 WASTE TEAZER]
However skilfully the work of mixing the stricks is performed in the
batching department, the degree of uniformity leaves something to be
desired; further improvement is still desirable and indeed necessary.
It need hardly be said, however, that the extent of the improvement,
and the general final result, are influenced greatly by the care
which is exercised in the preliminary processes.
The very fact of uniting 10 or 12 slivers at the feed of the
finisher card mixes 10 or 12 distinct lengths into another new length,
and, in addition, separates in some measure the fibres of each
individual sliver. It must not be taken for granted that the new
length of sliver is identical with each of the individual lengths
and ten or twelve times as bulky. A process of drafting takes place
in the finisher card, so that the fibres which compose the combined
10 or 12 slivers shall be drawn out to a draft of 8 to 16 or even
more; this means that for every yard of the group of slivers which
passes into the machine there is drawn out a length of 8 to 16 yards
or whatever the draft happens to be. The resulting sliver will
therefore be approximately two-thirds the bulk of each of the
original individual slivers. The actual ratio between them will
obviously depend upon the actual draft which is imparted to the
material by the relative velocities of the feed and delivery rollers.
It is only natural to expect that a certain amount of the fibrous
material will escape from the rollers; this forms what is known as
card waste. And in all subsequent machines there is produced, in
spite of all care, a percentage of the amount fed into the machine
which is not delivered as perfect material. All this waste from
various sources, e.g. thread waste, rove waste, card waste, ropes,
dust-shaker waste, etc., is ultimately utilized to produce sliver
for heavy sacking weft.
The dust-shaker, as its name implies, separates the dust from the
valuable fibrous material, and finally all the waste products are
passed through a waste teazer such as that made by Messrs. J. F. Low &
Co., Ltd., Monifieth, and illustrated in Fig. 16. The resulting mass
is then re-carded, perhaps along with other more valuable material,
and made into a sliver which is used, as stated above, in the
production of a cheap and comparatively thick weft such as that used
for sacking.