OVERLOCK MACHINE

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OVERLOCK MACHINE
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Introduction
Overlock 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 atleast one group
of threads pass around the edge of the material.
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Machine Terminology

• Bed working surface.
• Differential feed
• Differential feed regulator
• Feed dog
• Handwheel
• Knives
• Dummy needle
• Head

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• Lower looper
• Needle bar
• Presser bar lifter
• Presser foot
• Presser foot lifter
• SPM
• Spreader
• Stitch length regulator
• Table
• Thread finger or stitch tongue
• Upper looper
• Width selection knob.

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Basic features

• Generally called a serger in home sewing.
• Makes a class 500 that trims, stitch and overcast
  seams as they sew.
• Upto 1,500 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 upto 300.

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• Decorative effects can be achieved using special
  threads in loopers.
• In some, upper knife can be rotated up to
  disengage the cutting action.
• Stitch can be made using 2,3,4, or 5 threads,
  depending on the no. of needles and loopers.
• Seams sewn with a combination of conventional and
  overlock stitching can be used in a variety of
  fabrics and garment styles.

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Balanced stitch
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Selecting an overlock machine

• 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 mens
  slacks, lightweight fabrics or when using heavier
  decorative threads .

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• Used when stitching active wear, elastic and
  lace. Also hems can be sewn.
• Unsuitable for seaming, because does not hold
  plies securely, causing seam grim when stressed.
• Can be adjusted to sew a rolled edge.

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Three thread overlock

• Stitch type 504, most common overedge stitch.
• Also called basic serging stitch.
• One needle and two loopers.
• Stitch looks the same on both sides (good for
  reversibles).
• It has excellent stretch and recovery.
• Has narrow bight(3-5mm).

Stitch type 504
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• Used for finishing edges as a narrow, decorative,
  rolled edge on napkins and scarves.
• Also for seaming budget garments.
• Most useful for sewing knits, wovens (not in
  areas that receive stress).
• Can be used as a stable seam finish on loosely
  constructed, ravel prone fabrics.

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• 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.

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Four thread overlock with safety stitch

• Suitable for sewing both woven and knits.
• Can be used in areas that receive stress.
• Suitable for sewing blouses, shirts, skirts,
  dresses, pants, lingerie, actionwear, swimwear,
  and even sleepwear.

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Four thread overlock and chainstitch

• The left needle and the lower looper form a
  2-thread chain stitch.
• Suitable when sewing woven fabrics, even in area
  of stress.
• Stitch does not stretch therefore not used in
  knitted garment.
• Used when sewing shirts, blouses, skirts, pants,
  sleepwear, draperies.
• Used when fitting garments, since stitches are
  easily removed.
• Used when a wider seam allowance is desirable for
  strength (upholstery).

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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.
• Can sew rolled edges with either 2-thread or
  3-thread stitch.
• A very wide seam width is created when the chain
  is serged with 2 or 3 thread stitch.

Left lower looper
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Difference between portable and commercial
overedge machine

• Portable (home serger) used in small workrooms
  and classrooms, commercial used in industries.
• Portable is less expensive, more versatile,
  smaller, and easily serviced.
• Commercial one is faster (Upto 8,500spm) than
  portable(1,500spm)overedge.
• Commercial is permanently mounted on table,
  whereas portable is set on top of the table.
• Differential feed ratios on commercial overedge
  have a greater range.
• Commercial one has a knee lift, while portable
  does not.

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New developments
Adopting high quality alloy steelFully sealed needle bar drive mechanismsupported at both ends. Stabilized sewing withoutneedle oscillation is possible even at high speedand  the fully sealed structure prevents oil scatteringto eliminate oil-stained products.
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• Adopting oil forcing revolving device
• The new design assures fully lubrication of
  the needle bar prevent it from oil leaking
  problem .

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• Automatically oiling system with filter pump.

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• Thread trimming suction automatically by air-
  pressure system.

(OPTIONAL ATTACHMENT)
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• The new type upper threading structure

New design of the upper looper mechanism provides
easier threading operation .Besides, the looper
inserts from the front, whichmakes the replacing
work simple easy.
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Disadvantages of overedge machines

• Cant be used to attach patch pockets or for
  top stitching as it would trim along the seam
  line thus destroying the fabric.
• High thread users.
• Seams stitched must be pressed to one side
  rather than being pressed open and flat.

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Thank You