In regard to cloth manufacture, most yarns are utilized in the form
they leave the spinning frame, that is, as single yarns. On the
other hand, for certain branches of the trade, weaving included, it
is necessary to take two, three, or more of these single yarns and to
combine them by a process technically termed twisting, and sometimes
"doubling" when two single yarns only are combined.
Although the commonest method, so far as weaving requirements go, is
to twist two single yarns together to make a compound yarn, it is
not uncommon to combine a much higher number, indeed, sixteen or
more single yarns are often united for special purposes, but, when
this number is exceeded, the operation comes under the heading of
twines, ropes and the like. The twist or twine thus formed will have
the number of yarns regulated by the levelness and strength required
for the finished product. The same operation is conducted in the
making of strands for cordage, but when a number of these twines are
laid-up or twisted together, the name cord or rope is used to
distinguish them.[1]
[Footnote 1: See _Cordage and Cordage Hemp and Fibres_, by T.
Woodhouse and P. Kilgour.]
When two or three threads are united by twisting, the operation can
be conducted in a twisting frame which differs little from a
ordinary spinning frame, and hence need not be described. There may
be, however, appliances embodying some system of automatic stop
motion to bring the individual spindles to rest if one thread out of
any group which are being combined happens to break. When several
threads have to be twisted together, special types of twisting
frames are employed; these special machines are termed "tube twisters,"
and the individual threads pass through holes suitably placed in a
plate or disc before they reach the tube.
More or less elaborate methods of combining yarns are occasionally
adopted, but the reader is advised to consult the above-mentioned
work on Cordage and similar literature for detailed information.
When the yarn leaves the spinning frame, or the twisting frame, it
is made up according to requirements, and the general operations
which follow spinning and twisting are,--reeling, cop-winding, roll
or spool winding, mill warping or link warping. The type or class of
yarn, the purpose for which the yarn is to be used, or the equipment
of the manufacturer, determines which of these methods should be
used previous to despatching the yarn.
_Reeling_. Reeling is a comparatively simple operation, consisting
solely of winding the yarns from the spinning or twisting bobbins on
to a wide swift or reel of a suitable width and of a fixed diameter,
or rather circumference. Indeed, the circumference of the reel was
fixed by an Act of Convention of Estates, dating as far back as 1665
and as under:
"That no linen yarn be exported under the pain of confiscation, half
to the King and half to the attacher."
"That linen yarn be sold by weight and that no reel be shorter than
_ten quarters_."
The same size of reel has been adopted for all jute yarns. All such
yarns which are to be dyed, bleached, or otherwise treated must be
reeled in order that the liquor may easily penetrate the threads
which are obviously in a loose state. There are systems of dyeing
and bleaching yarns in cop, roll or beam form, but these are not
employed much in the jute industry. Large quantities of jute yarns
intended for export are reeled, partly because bundles form suitable
bales for transport, and partly because of the varied operations and
sizes of apparatus which obtain in foreign countries.
YARN TABLE FOR JUTE YARNS
90 inches, or 2-1/2 yards = 1 thread, or
the circumference of the reel
120 threads or 300 yards = 1 cut (or lea)
2 cuts or 600 yards = 1 heer
12 cuts or 3,600 yards = 1 standard hank
48 cuts or 14,400 yards = 1 spyndle
Since jute yarns are comparatively thick, it is only the very finest
yarns which contain 12 cuts per hank. The bulk of the yarn is made
up into 6-cut hanks. If the yarn should be extra thick, even 6 cuts
are too many to be combined, and one finds groups of 4 cuts, 3 cuts,
2 cuts, and even 1 cut. A convenient name for any group less than 12
cuts is a "mill-hank," because the number used is simply one of
convenience to enable the mill-hank to be satisfactorily placed on
the swift in the winding frame.
The reeling operation is useful in that it enables one to measure
the length of the yarn; indeed, the operation of reeling, or forming
the yarn into cuts and hanks, has always been used as the method of
designating the count, grist or number of the yarn. We have already
seen that the count of jute yarn is determined by the weight in lbs.
of one spyndle (14,400 yds.).
For 8 lb. per spyndle yarn, and for other yarns of about the same
count, it is usual to have provision for 24 spinning bobbins on the
reel. As the reel rotates, the yarn from these 24 bobbins is wound
round, say,
6 in. apart, and when the reel has made 120 revolutions, or 120
threads at each place from each bobbin, there will be 24 separate
cuts of yarn on the reel. When 120 threads have been reeled as
mentioned, a bell rings to warn the attendant that the cuts are
complete; the reel is then stopped, and a "lease-band" is tied round
each group of 120 threads.
A guide rod moves the thread guide laterally and slowly as the
reeling operation is proceeding so that each thread or round may be
in close proximity to its neighbour without riding on it, and this
movement of the thread extends to approximately 6 in., to accommodate
the 6 cuts which are to form the mill-hank.
Each time the reel has made 120 revolutions and the bell rings, the
reeler ties up the several cuts in the width, so that when the
mill-hank is complete, each individual cut will be distinct. In some
case, the two threads of the lease-band instead of being tied, are
simply crossed and recrossed at each cut, without of course breaking
the yarn which is being reeled, although effectively separating the
cuts. At the end of the operation (when the quantity of cuts for the
mill-hank has been reeled) the ends of the lease-band are tied.
The object of the lease-band is for facilitating the operation of
winding, and for enabling the length to be checked with approximate
correctness.
When the reel has been filled with, say, twenty-four 6-cut hanks,
there will evidently be 3 spyndles of yarn on the reel. The 24
mill-hanks are then slipped off the end of the reel, and the hanks
taken to the bundling stool or frame. Here they, along with others
of the same count, are made up into bundles which weigh from 54 lb.
to 60 lb. according to the count of the yarn. Each bundle contains a
number of complete hanks, and it is unusual to split a hank for the
purpose of maintaining an absolutely standard weight bundle. Indeed,
the bundles contain an even number of hanks, so that while there
would be exactly 56 lb. per bundle of 7 lb. yarn, or 8 lb. yarn,
there would be 60 lb in a bundle of 7-1/2 lb. yarn, and 54 lb.
in a bundle of 9 lb. yarn.
The chief point in reeling is to ensure that the correct number of
threads is in each cut, i.e. to obtain a "correct tell"; this ideal
condition may be impracticable in actual work, but it is wise to
approach it as closely as possible. Careless workers allow the reel
to run on after one or more spinning bobbins are empty, and this
yields what is known as "short tell." It is not uncommon to
introduce a bell wheel with, say, 123 or 124 teeth, instead of the
nominal 120 teeth, to compensate for this defect in reeling.