Sewing machine fundamentals, Principles of stitching

1. PRESENTED BY
Dewan Shafiur Rahman
Md. Jamil Hasan
BGMEA University of Fashion and Technology
Department of textile engineering
Apparel Manufacturing Engineering

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Group Members Id
142-052-0-155
142-060-0-155
Group: B

3. Mechanical systems
for assembly
( Sewing machine fundamentals, Principles
of stitching)

4. Introduction
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A sewing machine is a machine used to stitch fabric and other materials
together with thread. A sewing machine has some fundamentals through
which it can perform. Type of stitch, seam or any other specific operation
are greatly dependent on the fundamentals of the sewing machine. So It is
necessary to know the fundamentals of a sewing machine.

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Objectives
 To know about the fundamentals of a sewing machine.
 To know the type of sewing machine on the basis of the casting.
 To know about the lubrication system.
 To know about stitch forming principles.
 To know about the feed system.

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Sewing machine fundamentals
The parts of a sewing machine which are required to form a stitch, sew a
seam, or perform a specific sewing operation are known as sewing machine
fundamentals.
Sewing machine fundamentals include:
 A Casting
 A lubrication system
 A stitch forming system
 A feed system

7. The Casting
The machine casting is the metal form that provides the exterior shape to the machine.
Shapes of machine can vary according to the type of bed and the sewing function that is to
be performed and how piece goods are to be prepared. The casting houses the internal
workings that operate the sewing and feeding mechanism.
 Gears
 Shafts
 Cams
The casting determines the bed type and location of the cloth plate.
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The Casting (Bed type)
 Flat-bed machine
 Raised bed machine
 Post bed machine
 Side bed machine
 Cylinder bed

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Flat-bed sewing machine
Features:
 Flatbed/ Fully Submerged Bed Types ideal for small parts and where positioning
parts to the needle is a "slide" from the tabletop
 The large working area allows a wide range of application; the material can easily
be guided around the needle and the pressure foot.
 The basic type is used for all kinds of flat sewing work.
Stitch type:
 Lock stitch
 Chain stitch

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Raised bed sewing machine
Features:
 The entire machine is mounted on the top of the table.
 It is used when the garment to drape away from the needle for
better handling is needed
 It facilitates the assembly of pre sewn parts and is especially
suitable fir the fitting of accessories and special attachment .
Stitch type:
 Lock stitch
 Chain stitch

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Post bed sewing machine
Features:
 The needle plate and foot are mounted on a tall post that
facilitates sewing in tight spaces like inside sleeve, cap, or
shoes.
 It is also suitable for button sewing and bar tacking.
 It is used extensively in the making of clothing for knitted fabrics.
Stitch type:
 Lock stitch
 Chain stitch

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Side bed sewing machine
Features:
 This type of machines are specialized for sewing at
edges need only a small working area.
 It is used for sewing sleeve seams, inseams, or out
seams on pant legs, or other long seams in tight places.
Stitch Type:
 Chain stitch
 Over-edge stitch

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Lubrication system
Lubrication factors are the prime factors in maintenance, downtime, efficient operations
and long life time of various parts of the machine. The mechanical parts of sewing machine
like any other mechanical parts are need to be lubricated (oiled) to reduce friction and keep
mechanical parts moving freely.
High speed and temperature increase the need for lubrication because of increased friction.
There are two types of lubrication systems available.
 Manual
 Automatic

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Manual Lubrication System
In the former case oiling is done manually. In these
machines no special mechanism for oiling
is present. These machines are also
called as dry head machines.
The conventional sewing machine at
homes is also an example in which
manually oiling is done.

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Automatic Lubrication System
In automatic oiling systems different parts work in combination
with each other to ensure the effective supply
of oil to the required parts like-
 Oil pump
 Wick felt
 Oil gauge and oil sight window
 Oil distribution network (oil pipes)

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White
Automatic Lubrication System
Oil Pump Wick felt
Oil gauge

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Stitch forming system
Stitch forming system are the mechanical parts that when correctly synchronized forms
stitches, seams and then stitching. Various stitch forming mechanisms are:
 Thread control devices ( thread guides and thread tensions).
 Needles
 Bobbin case, bobbin and hooks
 Loppers
 Spreaders

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Stitch forming system
Thread Control Devices
Thread control devices include thread guides,
thread tensions and take-up. which are
necessary to provide uniform thread flow.
Thread guide
Thread guides control the position and
movement of thread. Damaged or faulty
thread guides can damage sewing thread
and cause thread breakage

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Stitch forming system
Thread take-ups
Thread take up control the supply of thread required to
form each stitch. It gives extra thread to the needle to
form the stitch but takes it away to set the stitch.
Tension Devices
Tension devices controls the flow and tension in the thread going to form
a stitch. Tension in the thread determines the balance and tightness of a
stitch. Tensioning devices consist of a pair of tension disks, a spring and a
thumb nut that can be adjusted to control the ease with which thread
passes between the disks.

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Stitch forming system
Hook
A hook is a rotating device encompassing the
bobbin case that picks up the needle thread
loop to form a lock stitch.
Needles
Needles carry the thread through
the fabric so a stitch can be sewn.

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Feeding System
The material handling components of machine are also called as the feeding system. For
a precise line of stitches to be formed fabric must be moved through the stitch forming
area of the machine with accuracy and precession.
The feeding system usually consists of the following parts:
 The presser foot
 The throat plate
 Feeding mechanism

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Feeding System
The presser foot
The presser foot is the upper part of the feeding mechanism. It
is mainly responsible for applying pressure and proper holding
of the fabric. The presser foot also controls the amount of
pressure as if light fabric is being sewed than more pressure
will be implemented however if heavy fabric is being sewed
than pressure in the presser foot is lowered to some extent .

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Feeding System
The Throat Plate
Throat plate is a metal plate that is present
directly under the needle. Throat plate has
openings for needle and feed dogs.

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Feeding System
Feed Mechanism
Feed mechanism control the direction
of fabric movement and the amount of
fabric movement for each stitch. Feed
mechanism affect stitch length and the
rate of travel.

25. Conclusion
In our presentation we have discussed on sewing machine fundamentals
which are the most important requirements for sewing operation in
a sewing machine. We have also discussed on principles of
stitching including some parts and some mechanisms.
Those things are very important for sewing. We can
say that they are the integral parts of sewing
operation. This is all about our
presentation.
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