This document discusses various work aids used in sewing machines to improve production and quality. It describes guides, compensating feet, specialized feet, stitching jigs, rack guides, lights, folders, slack feeders, elastification, thread cutters, and stackers. It also discusses sewing thread requirements including tensile strength, elongation, shrinkage, abrasion resistance, and fiber types. Finally, it covers thread numbering systems like ticket and tex numbering and factors that influence sewability.

1. Chapter 3
Work Aids, Velcro & Sewing
Thread
Course Teacher
Mohammad Ashraful Alam

2. Work Aids of Sewing Machines
Definition
The extra machine parts which may be attached to speed
up the production and improve quality in the sewing
machine are called work aid.
Objectives
• To increase the production.
• To improve the quality of garments.
• To reduce the work- load on operator.
• To reduce the time for handling.
• To control the garments quality.

3. 1. Guide
o Guides are used for correct sewing in predetermined
position or in a determined and proper distance form
edge of fabric.
o It is also used for straight and curved sewing to
increase the quality and productivity.
o Edge guides are used in over edge machine.
Different types of work aids used in Sewing Machine

4. 2. Compensating Foot
o This type of pressure foot has two sections and each section can
perform their works in different height with the help of spring.
o It is suitable to sew 1-2 mm distance from the edge of fabrics.
o Specially used for sewing more thickness fabrics, i.e. collar closing,
seam pocket etc.

5. 3. Specialized pressure foot
o It is used for attaching piped shape trimmings like
braid or elastic.
o It is suitable for sewing very close to chain or pipe.

6. 4. Stitching Jig
o Specially used for sewing small parts of garments.
o Dye cutting parts are attached with the stitching jig.
o It is made with two aluminum or plastic seat whose one end is joined
with wage.
o Two or more fabric pattern is placed properly in jig; the seats are closed
together and sewing along slot line.
o Extensively used in collar and cuff.
Disadvantages of Stitching Jig :
 The additional allowance is required due to not movement of the fabric
during sewing in stitching jig. So fabric wastage is more.
 Skilled and experienced operator is required for the controlling of
stitch length properly.
 The jig should be changed when the style is changed. For this, much
time and cost required.

7. Fig : Stitching Jig

8. 5. Rack Guide
o It is used to attach lace, braid and elastic with garments parts.
o Rack guide is used at the front of pressure foot for the placement of
lace or braiding the predetermined position from the rolls.
o The lace or braid rolls are placed in rack guide.

9. 6. Light
o Marking with chalk or pencil is required on the fabric for sewing of parts
of the garments.
o The chalk spot or marking are found after washing and sewing.
o In order to remove this problem special marker used which are not
visible in normal light but visible in ultraviolet ray.
o The light can reflected as thin beam along needle.

10. 7. Folder
o A sewing machine attachment which folds one or more materials into
the desired configuration for sewing is called folder.
o It may be placed in the middle of pressure foot or in front of pressure
foot.
o It is used to increase the production and to ensure the quality of
products.

11. 8. Slack Feeder
o Lace, braids, tape or elastic are supplied in roll
forms exists tension and attached in the garments in
tension condition, seam pucker may be created due
to shrinkage. Slack feeder is used to avoid this
problem.
o In slack feeder, lace or braid is opened from rolls
with the help of motor and roller. Then hangs as a
loop form. So tension is reduced before sewing.

12. 9. Elastication
o It helps to join elastic to the garments easily and at a
higher speed.
o Elastication can be made using folder in the front of
pressure foot.
o Computerized elastication machine is used to
increase products quality and productivity.

13. 10. Thread Cutter
o This is a mechanical device in sewing machine used to cut thread at a
regular distance.
o After completing the sewing, the thread is cut by ‘Manually operated
sewing machines’ or ‘Automatic operated sewing machines’.

14. 11. Latch Back Device
o In over edge sewing machine, the thread cutting
ends can be secured with the air flow called latch
back. In this method, one end can be latch back.
o In present, in latch back sewing machine, electronic
edge sensor is added and both ends of thread can be
latch back.

15. 12. Compressed Air
o It is used to remove curling from fabrics, specially
knitted fabrics.
o The compressed air is flown vertically with the
fabric edge in front of edged trimmer to become
straight by reducing the curling of fabric edges.

16. 13. Stacker
o It is used to shift garments from one machine to
next machine through hanging layer.
o It reduces time, manpower and also protects the
garments from unexpected fold, dust and dirt.

17. Sewing Thread
Sewing threads are special type of yarns. Plied yarns are used as sewing thread. They
are engineered and designed to pass through a sewing m/c rapidly. To form a stitch
efficiently and to function in a sewn products without breakage or being distorted for at
least the useful life of the product

18. Sewing thread requirement
The requirements can be-
1.Functional Requirements:
• Tensile strength: The strength that is required for pulling and breaking of a thread is
called the tensile strength. It is generally expressed in gram, kilograms or in pound.
• Tenacity: Tenacity of a thread is obtained by dividing the tensile strength of thread by
its count .The tensile strength of thread depends on its count. The higher the thickness
the higher the tensile strength.

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• Elongation at break: During the time of breaking of the thread due to the
application of force on it , the length which is stretched beyond its original
length, is called the elongation at break. It is expressed as %.
• Shrinkage: Due to heat or washing with water, the amount that a thread shrinks
from its original length is called the shrinkage . The shrinkage should be less
than 2%.
• Abrasion resistance: The abrasion resistance of a thread is considered with the
abrasion resistance of another same thread.
• Color fastness: Color fastness is the resistance of sewing thread against
various factors like wash, heat, abrasion etc.

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• Free from knots and faults: Sewing thread should be free from knots and faults to give smooth
performance.
2. Serviceability: During sewing , threads are subjected to abrasion over needles and fabric threads.
There is a loss of strength during and after sewing during fabric use. Sewing thread should have high
abrasion resistance so that loss of strength is minimum. For a good serviceability , seam must be firm .
To avoid puckering of garments around the seams , the thread shrinkage should be generally less than
2% during washing.
3.Aesthetic : color , shade , luster smoothness , fitness are some of aesthetic related characteristics of
sewing threads. Certain amount of hairiness in sewing thread has positive effect on sewing but this
effect has to be sacrificed for appearance .
4. Cost consideration: From the raw materials aspect, sewing thread of silk is expensive. A higher
melting sewing thread may be expensive but it may affect needle and fabric also

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• Fiber type sewing thread:
1. Natural fiber sewing thread:
• Cotton: The natural fiber in commonest use is cotton. They provide good sewing performance
terms of loop formation . They are soft, having a high wet shrinkage. They may cause seam
puckering. Glazed cotton threads have smoother surface and better resistance to abrasion
than unglazed cotton threads. Mercerized cotton threads are also used as they have increased
luster and higher tenacity.
• Silk: Threads of silk give good sewing performance. They are used in couture and bespoke
tailoring. Silk threads are very shiny and expensive.
2. Regenerated fiber sewing thread: Sewing thread from viscose does not have high strength or
durability but they are of high lustrous property and suitable for embroidery. They are not
suitable for those garments which are washed more in water.

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3. Synthetic fiber sewing thread :
• Polyester thread: polyester thread having low cost, very low laundry shrinkage , high abrasion
resistance , high strength, is the most commonly used synthetic fiber sewing thread.If it is
washed in water or boiled upto 150 degree centigrade temperature , it doesn’t shrink.
• Nylon thread : The use of nylon thread for sewing of regular garments is very limited. Due to its
high extensibility, nylon thread is used in sewing of swim wear and some knitted garments.
• Aramid thread: It is a very costly thread . Used in sewing of garments which are flame resistant.
• PTFE thread: PTFE thread is used in sewing of garments having flame resistance , melting
ressitance and having the quality of chemical reaction prevention.

23. Thread numbering
Ticket numbering : Ticket numbering is a commercial numbering system. Ticket numbers are merely
the manufacturer’s reference numbers for the size of a given thread. The Metric Count and Cotton
Count systems use ticket numbering system to give an easy approximation of the specific size of the
finished thread.
In Metric Ticket system, the figure quoted for thread size is the length that would weigh 3 grams. The
thread could be made from a single yarn or multiple yarns.
For example, a thread of Tex 40 is Tkt. 75 and Nm 80/2 is Tkt. 120

24. Tex Numbering :
Tex is a metric system of textile yarn and thread numbering. Tex is defined as weight of 1000 meters
thread in grams.
For example, Tex 40 – a length of 1000 meters of thread will gives 40 grams of weight.
Tkt. = (1000/Tex No.) X 3 or
Tkt. = Nm X 3

25. Thread sewability
• 'Sew ability' of thread is a term used to describe a sewing thread’s
performance. A thread with good sew ability is uniform in diameter with a
good surface finish. Longitudinal uniformity of thread contributes to uniform
strength and reduced friction, as it passes through the stitch forming
mechanisms. It also minimizes thread breakages and the associated costs
incurred from rethreading machines, repairing stitches and producing inferior
quality products.

26. Sewability parameters
• The parameters that define the superior sewability of thread are:
• No breakages in high-speed sewing
• Consistent stitch formation
• No skipped stitches
• Evenness, to prevent changes in tension during sewing
• A high level of abrasion resistance
• Sufficient surface smoothness, to pass easily through the machine guides