overlock machines

OVERLOCK MACHINE

Submitted by:

Nagaraj Ramachandra Bhat

[MFT/14/510]

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.

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%.

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.

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

Overlock Machines

STITCH TYPES PRODUCED

BY OVERLOCK MACHINE.

Stitch Type 501 [ 1 thread overedge]





Overlock machine feeding

system Differential drop feed:

It utilizes two independently driven feeddogs. The stroke of each feed dog canbe adjusted separately.

If the stroke of the front feed dog isgreater, then the fabric may be gather asit is sewn.

If the rear feed dog has the greaterstroke, then the fabric may be stretchedto provide a more extensible seam.

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.

Ratio Of Differential feed

THREADING

Selecting an overlock

machine:

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.

Single Thread Overedge

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.

Stitch type 503

Two Thread Overedge

Three thread overlock:

Stitch type 504, most common overedgestitch.

Stitch formed by interaction betweenvertical movement of needle and horizontalmovement of two loopers.

Stitch looks the same on both sides

To make a 504 stitch, the needle threadstitches the flies together when it interlockswith the under looper thread on theunderside and upper looper thread on thetop side.

◦ Used for finishing edges as a narrow, decorative, rolled

edge on napkins and scarves.

◦ Most useful for sewing knits, wovens

◦

Upper

looper

Lower looper

Stitch Formation Of 504

PHASE 1


PHASE 2


PHASE 3

Three Thread Overedge

Four thread overlock:

It will stitch a chain stitch or a safetystitch as it stitches and overcastsseams.

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, actionwear, swimwear, and even sleepwear.

Stitch type 514

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

Four Thread Overedge

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.

Stitch type 516

Five Thread Overedge

Balanced Stitch

Unbalanced stitch

Loopers used in Overlock

Machine

What Is The Problem

With Overlock

Machine?

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.

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.

Working Principle

Automatically sensing the completion ofstitching, by sensing of the trailing portion ofthe first cloth by the sewing machine;

Automatically engaging the first cloth inresponse to the sensing and moving the firstcloth away from the stitching needle morequickly then the sewing machine stitchesthe thread chain, to pull the excess chainextending past the trailing portion of the firstcloth relatively taut.

Automatically severing the excess threadchain from the trailing portion of the firstgarment when the excess thread chain isrelatively taut.

Automatically positioning the excessthread chain with respect to the secondcloth so that the excess thread chain isstitched to the second cloth by thesewing machine, so that neither clothhas free stitches extending there from.

Air jet device

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.

Chain Cutting device

New developments:

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.

Adopting oil forcing revolving

device: The new design assures fully lubrication of

the needle bar & prevent it from oil leaking

problem.

Automatically oiling system

with filter pump.

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.

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.

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

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