Sewing Machine Feed Mechanism

1. Submitted by :
1. Siam Uddin [172-008-0-155]
2. Md. Mustafizur Rahman [172-013-0-155]
3. Dhrubo Adhikary [172-015-0-155]
Sewing Machine Feed Mechanism
Apparel Manufacturing Engineering | |
• Submitted to:
MD. RAMIJ
HOWLADER
Assistant Professor,
Dept. of TE, BGMEA
University of Fashion
& Technology

2. Sewing Machine
Feed Mechanism

4. Introduction
What is feed mechanism
Feed mechanisms is the basic
motion of needles, loopers and
bobbins, the means for moving the
material or fabrics being stitched
from one stitch position to the next
is called feed mechanism. This is a
very important part of the sewing
machine.

5. Function of feed mechanism
• Proper seam appearance.
• Proper stitching as required.
• Controlling of SPI(stitch per inch).
• To avoid different sewing faults.
• Move forward and backward of sewn fabric.
• Some crease effect is formed according to the design.

6. Different parts of a feed mechanism
• There are so many types of feed
mechanisms are available according to
the desired function and machine. But
common three parts are must whatever
the type of feed mechanism is. The
parts are:
1. Throat plate/ Needle plate/ Feed Plate
2. Feed dog
3. Pressure foot

7. Throat plate/ Needle plate/ Feed Plate
• The part of the bed of the sewing machine which has openings for the
needle and for feed dog penetrations and which provides localized support
to the material. It’s surface is very smooth. Due to the smooth surface fabric
can be feed easily. It is also called needle plate. It has one or more slots
through which feed dog can move forward and backward. It has a hole
through which needle can move up and down with the thread. Size of this
hole should not exceed more than 30% of needle size. If it is, the fabric can
be pushed into the hole with each penetration of the needle which is called
Flagging.
Flagging: Type of sewn seam failure in which some yarns slip out of the
seam.

8. Feed dog
• A toothed element which acts on the surface of material is being
sewn to move it in a controlled way during stitching. The action
in normally on the lower surface of the material, but
mechanisms which act on the upper surface are also in use. For
most of the time, the operative motion is forward, but in
specific cases the motion is reversed. The main function of this
part is to move sewn fabric after making individual stitch as
predetermined length. To prevent the slippage of the fabric, the
upper parts of the feed dog are made toothed.

9. Feed dog
The up and down movement of the needle should be carefully handle.
When fabric is moved forward the needle must be out of action or to
its maximum position. The pitch of tooth on the surface of the feed
dog may be different in number and size.
 For light fabric : Pitch 1.0mm- 1.25mm
 For medium fabric : Pitch 1.3mm- 1.6mm
 For heavy fabric : Pitch about 2.5mm

10. Pressure foot
• This is an element which is used to constrain the movement of the
material during stitch formation by applying to it an adjustable
downward pressure. It works in conjunction with the throat plate
and feed dog to achieve controlled movement of the material and
correct stitch formation. Different design of pressure foot are in use;
the most common have a solid or hinged surface which controls the
material. It is used to give an adjustable downward pressure on the
fabric with spring pressure. So that fabric can not move up and
down with needle. Lower surface of the pressure foot is very
smooth to prevent less friction between fabric and pressure foot.

11. Types of feed mechanism
1. Drop feed mechanism.
2. Differential bottom feed mechanism.
3. Adjustable top feed mechanism.
4. Needle feed mechanism.
5. Unisom feed mechanism.
6. Puller feed mechanism.

12. DROP FEED MECHANISM

13. DROP FEED MECHANISM
This is the simplest and widely used feed mechanism.
When two plies of fabrics are sewn by this mechanism,
the feed dog moves backward and come upward through
the slot of the throat plate and contacted with lower
surface of the fabric. Spring loaded pressure foot gives
pressure on the upper side of the fabric. Then the fabric
moves forward a step and then feed dog descend from the
fabric and moves down again below the throat plate. In
this way its lateral movement is completed. Sometimes it
is seen that, the lower ply of fabric is feed more than the
upper ply. This is called ply shifting or differential
feeding pucker. With the same reason, sometimes ropping
is occurred during marking of hem.

14. PROBLEMS OF DROP FEED
• When two plies fabrics are sewn- lower ply moves forward by the
help of feed dog.
• So two plies of fabric can not move forward at the same speed. As a
result lower ply is more fed than upper ply.
• This is called ply shifting/differential feeding pucker/feeding
pucker.
• Sometimes roping is occurred during making of hem for ply
shifting.
• It pitch of stitch s pitch of feeding dog same then fabric may be
damaged for repeating contact of feed dog teeth & fabric at the
same place.

15. DIFFERENTIAL BOTTOM FEED

16. DIFFERENTIAL BOTTOM FEED
• Modification of drop feed system.
• In this feed mechanism the feed dog consists of 2 section one at
front & one at back of the needle.
• Two segment can be moved at the same speed or different
speed.
• Crease effect can be produced by running the feed dog with
different speed
• This system is used in Chain stitch, Lock stitch and Over edge
chain stitch machine.

17. Adjustable top Feed System

18. Adjustable top Feed System
• This is a top feed system in which, the presser foot is in two section.
• One holding the fabric in position while the needle form the stitch
and the other having length on the lower side & moving or waking in
such a w ay that the top ply is taken along, positively while needle is
out of the materials.
• It can be found different types of machine combined with the
adjustable top feed and drop feed system or combined with
adjustable top feed and differential bottom feed.
• Combination of adjustable top feed & differential bottom feed can
make crease effect to the fabric, also used for Overedge stitching.

19. NEEDLE FEED

20. NEEDLE FEED
• Another name of needle feed mechanism is “Compound feed”. Needle
feed is the feed system in which the needle itself moves forwards and
backwards.
• The needle enters the fabric, so there is possibility of producing a large
hole into the fabric. To remove this, compound feed is used which
comprising synchronized needle feed and drop feed mechanism.
• High thickness and hollow fabric are sewn by this mechanism. Stitch
length can be changed by the changing the stroke of both needle and
feed dog.
• Used for stitching slippery fabric as well heavy material like leather,
carpet etc.

21. Unison Feed System Mechanism

22. Unison Feed System Mechanism
• A feed mechanism providing needle feed in addition to the top
and bottom feed. Here two pressure foot are placed in the
middle of each other and are not motioned with the same time.
• The presser foot in the middle & the needle are driven at the
same time toward the same direction.
• No possibility of ply shifting.
• Suitable for sewing stitch fabric & adhesive types of fabric.
• Normally not so used unless special case.

23. Puller Feed Mechanism

24. Puller Feed Mechanism
• Modification of drop feed system.
• A pair of roller used. These rollers give a pulling motion on the
fabric behind the presser foot.
• Top roller is generally driven by machine whitest the lower one
moves due to control & presser of the top roller.
• Puller roller is motioned at a higher speed than the drop feed.
• There is no possibility of ply shifting or ropping.
• Useful in multi needle machine specially for wiast band making.
• Generally suitable for straight runs or large radius curve only.

25. Conclusion
Every sewing machine features a form
of feeding that allow them to move
materials to create a stitch. Because of
this, it’s beneficial to understand the
differences between these feeding
mechanisms .