The document describes an overlock machine, which is a specialized sewing machine used to finish fabric edges and seams. It can produce stitches at speeds up to 5000 stitches per minute. The overlock machine makes stitches using 1-5 threads depending on the number of needles and loopers. Common stitch types include 3-thread, 4-thread, and 5-thread overlocks. Key features of the overlock machine include its differential feed system and ability to stretch stitching up to 300%. Problems with thread chains are addressed through the use of a backlatcher or chain cutting device.

1. OVERLOCK MACHINE
 Submitted by:
Nagaraj Ramachandra Bhat
[MFT/14/510]

2. INTRODUCTION
 Over lock machine is a special purpose
machine used for finishing edges and
sometimes for seaming. It falls under the
class 500.
 Stitch types in this class are formed with
one or more groups of threads and have a
general characteristics that loops from at
least one group of threads pass around the
edge of the material.

3. BASIC FEATURES
 Makes a class 500 that trims, stitch and
overcast seams as they sew.
 Up to 5000 stitches per minute.
 Stitch length vary from 0-5mm.
 Used to sew wide variety of items- from
placemats to draperies and even
sportswear.
 Stitch is very elastic and can stretch up to
300%.

4.  Stitch can be made using 1,2,3,4, or
5 threads, depending on the no. of
needles and looper.
 Seams sewn with a combination of
conventional and over lock stitching
can be used in a variety of fabrics
and garment styles.

5. Overlock machine
Types of stitch Lock Stitch
Machine speed 2500[s.p.m]
Type of motor used Induction motor
Type of lubrication Automatic
Oil used G2
Type of feed Deferential feed
Type of needle DP*5
Type of bed Cylindrical Bed
Purpose of Machine Loops Attaching
Power consumption 3/4HP

6. Overlock Machines

7. STITCH TYPES PRODUCED
BY OVERLOCK MACHINE.
 Stitch Type 501 [ 1 thread overedge]
 Stitch Type 503 [ 2 thread overedge]
 Stitch Type 504 [ 3 thread overedge]
 Stitch Type 514 [ 4 thread overedge]
 Stitch Type 516 [ 5 thread overedge]

8. Overlock machine feeding
system
 Differential drop feed:
It utilizes two independently driven feed
dogs. The stroke of each feed dog can
be adjusted separately.
If the stroke of the front feed dog is
greater, then the fabric may be gather as
it is sewn.
If the rear feed dog has the greater
stroke, then the fabric may be stretched
to provide a more extensible seam.

9. Differential feed regulator
 The differential feed
is regulated by the
differential feed
regulator, which
adjust the rate at
which the material is
fed under the foot.
 It is used to prevent
the fluting or wavy
seams on stretch
material.

10. Ratio Of Differential feed

11. THREADING

12. Selecting an overlock
machine:

13. Single thread overlock:
• Stitch type 501.
• One needle and one looper.
• Only used in home application.
• Has little effect on fabric drape.
• Unsuitable for seaming, because does not
hold plies securely, causing seam grim
when stressed.

14. Single Thread Overedge

15. Two thread overlock:
• Stitch type 503.
• One needle and one looper.
• Best for finishing seam edges and
allowances.
• Has little effect on fabric drape, and rarely
causes a pressing imprint.
• Frequently used for serging edges on men’s
slacks, lightweight fabrics.
• Unsuitable for seaming, because does not
hold plies securely, causing seam grim when
stressed.

16. Stitch type 503

17. Two Thread Overedge

18. Three thread overlock:
 Stitch type 504, most common overedge
stitch.
 Stitch formed by interaction between
vertical movement of needle and horizontal
movement of two loopers.
 Stitch looks the same on both sides
 To make a 504 stitch, the needle thread
stitches the flies together when it interlocks
with the under looper thread on the
underside and upper looper thread on the
top side.

19. ◦ Used for finishing edges as a narrow, decorative, rolled
edge on napkins and scarves.
◦ Most useful for sewing knits, wovens
◦
Upper
looper
Lower looper

20. Stitch Formation Of 504
PHASE 1

21. Stitch Formation Of 504
PHASE 2

22. Stitch Formation Of 504
PHASE 3

23. Three Thread Overedge

24. Four thread overlock:
 It will stitch a chain stitch or a safety
stitch as it stitches and overcasts
seams.
 Two needles and two loopers.
 Can be converted to both two and three
thread overlock
 All 4 threads are necessary to sew a
serged seam.
 Suitable for sewing blouses, shirts,
skirts, dresses, pants, lingerie, action
wear, swimwear, and even sleepwear.

25. Stitch type 514

26. Machine specifications
CONTENTS DESCRIPTION
Maximum Sewing Speed 6500 spm
Stitch Type 514
Stitch Length 1.0 to 3.6mm
Stitch Width 6.2mm
Needle Gauge 2.2mm
Differential Ratio 1:1.29 to 1:0.6
Needle System B 27
Lubrication System Automatic

27. Four Thread Overedge

28. Five thread overlock:
 A 2-thread chain stitch combined with a
3-thread overlock.
 2 needles and 3 loopers.
 The left needle and lower looper form a
2-thread chain stitch.
 The seam is very durable, particularly for
wovens.
 A very wide seam width is created when
the chain is serged with 2 or 3 thread
stitch.

29. Stitch type 516

30. Five Thread Overedge

31. Balanced Stitch

32. Unbalanced stitch

33. Loopers used in Overlock
Machine

34. What Is The Problem
With Overlock
Machine?

35. Problems:
 On completion of the first garment, the
formation of 1-1.5 inch long thread
chain;
 Spoiling the appearance of the second
garment as it gets stitched along with
it;
 Finishing of the garment by manual
cutting of the chain leading to higher
labour costs and waste of time.

36. BackLatcher Device
 An attachment for semi-automatic and
automatic sewing machine that
ensures that any excess thread chain
extending from the leading or trailing
edge of the garment during an
operation on the garment on the
machine is directly stitched to the next
garment so that no loose or free ends
of the chain are remained.

37. Working Principle
 Automatically sensing the completion of
stitching, by sensing of the trailing portion of
the first cloth by the sewing machine;
 Automatically engaging the first cloth in
response to the sensing and moving the first
cloth away from the stitching needle more
quickly then the sewing machine stitches
the thread chain, to pull the excess chain
extending past the trailing portion of the first
cloth relatively taut.

38.  Automatically severing the excess thread
chain from the trailing portion of the first
garment when the excess thread chain is
relatively taut.
 Automatically positioning the excess
thread chain with respect to the second
cloth so that the excess thread chain is
stitched to the second cloth by the
sewing machine, so that neither cloth
has free stitches extending there from.

39. Air jet device

40. Chain Cutting Device
 The device at the side of the overlock
machine for the manual cutting of the
protruding soft chain of threads is
called chain cutting device.
 It is both horizontal and vertical.
 The severing is done automatically by
sensor in the automatic machine.

41. Chain Cutting device

42. New developments:

43. Adopting high quality alloy
steel
 Fully sealed needle bar drive mechanism
supported at both ends. Stabilized sewing without
needle oscillation is possible even at high speed
and the fully sealed structure prevents oil scattering
to eliminate oil-stained products.

44. Adopting oil forcing revolving
device:
 The new design assures fully lubrication of
the needle bar & prevent it from oil leaking
problem.

45. Automatically oiling system
with filter pump.

46. The new type upper
threading structure:
 New design of the
upper looper
mechanism
provides easier
threading operation .
Besides, the looper
inserts from the
front, which
makes the replacing
work simple & easy.

47. Disadvantages of overedge
machines:
 Can’t be used to attach patch pockets
or for top stitching as it would trim
along the seam line thus destroying
the fabric.
 High thread consumption.

48. REFERENCES
 Sewing for the Apparel Industry By
Claire Shaefffer.
 Google
 Cloth Manufacturing
 Sewing Machine operational Manual.
 Technology of clothing manufacture
By Carr and Lethem
 Yamato Overlock Machine Catalogue

49. THANK YOU