Functions of various machines in sewing thread manufacturing process:
Yarn singeing
Sewing thread
must be singed to ensure that the projecting fibres do not interfere
with downstream processing. Percentage of singeing can be achieved
varied by varying the yarn collection speed. Hair removal efficiency at
singeing machine is normally 30 - 50%. Flame temperature is around 800
oC. Singeing is mainly done in Cotton Sewing Threads.
Features
- The heart of the machine - the burner, serves to singe reliably the projecting fibres of yarn running through at high speed, without inflicting burns on yarn itself. There is a choice between the gas burner and the electric burner. Gas burner are widely used. The gas burner consumes about 55 gm of natural, propane or butane gas an hour, depending on singeing rate and yarn type.
- Speed: 300-1200 m/min.
Hank to cone winding
• Conversion of hank in to cone of suitable weight
• Waxing for reducing co-officient of friction in sewing thread .
Features of new machines:
• Twin Input Rollers:
At the front of the head are the twin-input rollers, set to a fixed
speed but proportional to the winding speed. The main functions of this
unit are to eliminate unwanted tensions prior to yarn entering waxing
unit.
• The speed of machine ranging from 400-700 mpm, with possible traverse from150-200 mm.
Polishing
Some
threads for special end uses like leather industries, bag stitching,
kite flying are treated with starch, softeners, whitener, etc on this
machine. Cooked starch is mixed with other chemicals and different
recipes are made for different qualities depending on the end uses.
Main objectives of polishing are:
• Extra ordinary smooth surface
• Thread becomes round.
• Stiffness increases.
• Increase in tensile strength (7-10%).
Cross winding and lubrication
• Winding in various types of sewing thread packages like cone, cop , tube, ball, vicone and spool.
• Threads are treated with special waxes for achieving best workability during sewing operation.
•
Lick roller lubrication is applied on industrial sewing thread where
thread has to run on high speed sewing machine; the basic ingredient of
the most of the lubricants is parafin wax. Although silicones are also
used because of their stability to heat and various additives are also
included to give some special properties.
Geometry of packages
Threads
are wound in many forms. Small length spools are employed in retail
store distribution, whereas somewhat larger spools are used to a limited
extent industrially. Some of the very fine soft threads are wound on
cones, very coarse soft threads are in skein form, but the largest
proportion by far is wound on the one headed tube with base or straight
tubes. These packages in some instances are put on a weight basis;
however, the larger percentage is marked on a length basis. Ready-wound
bobbins in a number of styles to accommodate the various sewing machines
employed are also available. Cross winding threads are generally laid
in with traverse ratio 1: 6 (one double traverse = six spindle
revolution) and 1: 4 for coarser counts.
The following types of packages are used in sewing threads (with commonly used dimensions).
Spool: Spools
are small flanged plastic or wooden bobbins, they are both with tapered
(so-called Diabolo spools) and straight flanges. Mainly parallel
winding (because side unwinding is easy) is done. Cross-windings are
also possible on the spools. They contain relatively short length of
100-500 meter thread. The length of traverse on spool is 2.9-3.8 cm.
End uses: Upholstery, footwear, leather goods manufacturing, and in hand sewing operations.
Cop:
Cops
are small cylindrical flangeless spools, with precision cross winding.
They are mostly made of paper and plastic. They are of two types, small
Cop (Tube) and medium Cop (Cop). The lack of flanges facilitates regular
off winding on industrial sewing machines although their small diameter
makes them less well suited to the faster thread take off machines.
Smaller Cops are popular make-up in fashion trades, where a variety of
shades are used and production runs for any one colour or style of
garments. The length of thread wound ranges from 100-2000 m on small cop
and 400-4000 m on cop. The length of traverse on small cop is 5 - 6.3
cm and on cop is10 cm.
End uses: Kite flying, Upholstery, ready-made garment, tailoring, hosiery, umbrella, and shoe stitching
Cone:
This
is self-supporting, cross wound conical package. It is easier to
withdraw yarn over end from a cone than from a cheese and because of
this, cone is more widely used. They contain relatively long lengths
1000-25000 m with length of traverse ranging from 10-15 cm. They give
trouble free thread unwinding at intermittent or continuous high speeds.
Cones are the most economical packages for conventional sewing threads
in situations where thread consumption is high and production runs are
long.
End uses: ready made garment, tailoring, hosiery, leather stitching, Upholstery, shoe stitching, denim, embroidery, and kite flying.
Vicone or King Spool:
Vicones
are parallel tubes or low angled cones with an additional base in the
form of a raised flange, which may incorporate a small tip. The build of
vicone depends on the exact conformity of the taper with the angle of
vicone’s base. Coarse yarns require a large traverse for the taper --
fine yarn a small one. They contain lengths of 1000-5000 m with length
of traverse 6.5-9 cm.
End uses: embroidery, core-spun, and filament threads .
Prewound Bobbin:
Prewound
bobbins are precision parallel wound thread package designed to replace
metal bobbins on a variety of lock stitch machines.
Skein:
A
very small hank of soft twisted plied thread (around 8 m) of coarse
count, is parallel wound with the help rotating flyer, which withdraws
the thread from the supply package cone.
End uses: embroidery.
Ball:
A
typical ball like structure, wound with the help of four types of
different winding. They are: Rough base winding, form winding, surface
layer winding, and circumference winding. The initial winding provides
firmness at the base. Next winding process makes space for placing the
identification ticket. The third stage of winding provides firm gripping
of the ticket. The last stage of winding makes a band over the ball,
which retains its shape. An easy unwinding of thread is possible.
End uses: embroidery, fishing net and bag closing.
Cocoon:
Cocoons
are self-supporting i.e. center-less thread package specially designed
for the insertion in the shuttle of multi needle quilting and some types
of embroidery. Cocoons are used in the shuttle of multi needle quilting
and some types of embroidery machines.
