stitch machines

8/3/2019 Stitch Machines

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OPERATION FLOW IN A GARMENTFACTORY( Stitching)

Sewing Machine Feeding System

Throat plateProvides openings forthe needle and the feed dog

The needle hole in throatplate should be onlyabout 30percent larger than the size of theneedle, since if this hole is too large , fabric canbe pushed into the hole with each penetrationof the needle , a problem known as flagging.

The surface of the throatplate should be free ofcuts orabrasion. to enable the material to freely

pass over it without damaging the fabric.


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Sewing Machine FeedingSystem

Feed DogThe purpose of the feed dog is tomove the fabric along by a

predetermined amount betweensuccessive stitches.

Types of feed dog teeth: Saw tooth ( Single direction feeding) Upright ( Uniform two direction

feeding)

Diamond ( feedingof fine fabric)


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Feed Dog ( Considerations) The motion of the needle in up and down

direction must be accurately synchronized with

the elliptical motion of the feed dog so that themovementof the fabriconly takes place whenthe needle is outof the fabric.

Forsewing light to medium weight fabrics, atooth pitch ( distance from peak topeak) of 1.3to 1.6 mm is normal

The peaks can be slightlyroundedoff if damageoccurs on fine fabric.

On very light weight fabric, sagging can appearbetween the teeth andpuckercan occuraftersewing as a result. Fine toothed feed dog with apitch ofonly 1.0 to 1.25 mm can be used toprevent this.


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Feed Dog ( Considerations) On heavyweight fabric a certain amountof sagging is

required forsatisfactory feeding in orderto keep bothplies together. In this case, coarserfeed dogs of 2.5

mm tooth pitch may be used. On very delicate fabrics, damage ormarkingof the

fabric may arise against the feed dog, despiteroundingoff the teeth. In this case a rubbercoatedfeed dog with no sharp teeth at all may be used.

Of more importance in preventing damage duringfeeding is a deliberate mismatch between stitch sizeand feed dog size. If forexample a seam is sewn at 6stitchespercm using a feed dog with 6 teeth percm ,then a tooth willrepeatedly hit the same section of thefabric as it moves past and markingof the fabricoreven damage couldoccur.


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Sewing Machine Feeding

System

PresserFoot Presses the material being

sewn against the feed dog and

the throatplate.

Facilitates stitch formation andfeeding


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Needle

The needle has to be able topenetrate the material being

sewn , without damaging it ,by pushing the yarn side.

Selection of the needle sizewill depend upon :

Material being sewn

The size of sewing thread

The type of seam

Stitch type


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OPERATION FLOW IN A GARMENTFACTORY( Stitching Dept.)

Needles for Textile

Cloth point needles are usedfor sewing textile materialwhich has a round crosssection and the tip at the endof the point can vary inshape to suit the particularmaterial being sewn. Clothpoints needle can further beclassified as:

Set point needle Ball point needle

Cutting point needles areused sewing leather andlaminated textiles.


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Set point Needles

Slim set point needle:needles

Used for fine, denselywoven fabric but not suitablefor knitted fabric.

Set cloth point:Slightly rounded.

Displaces the yarns ofmaterial being sewn w/odamaging.Most versatile

point shape. Heavy set point :

Strongly blunted.Especially used for buttonsewing machine


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Ball point Needles

Light Ball Point

Used for sensitive

fabrics such as knits toprevent damage to the loop.

Medium & Heavy Ball

point:

Used for elastic material

containing elastomericthreads . The threads are

not pierced but displaced.


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Single Needle lock

stitch machine

2- Needle lock stitch

machine

Sewing Machines


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Over-lock/ Safety

stitch machine

High speed flat bed top and bottom

stitch machine ( 2 needle / 3

needle

Sewing Machines


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Button Sewing

machine

Button Sewing machine

with tying knot

Sewing Machines


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Cylinder bed lockstitch

Bartacking machine

1-Needle Button holing

machine

Sewing Machines


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OPERATION FLOW IN A GARMENT

FACTORY(SAMPLE DEVELOPMENT )

DOS & DONTS

Develop and document a standardoperatingprocedureforthe article clearly describing each step and theaccepted quality level.

The production manger/ supervisormust involve in thesample development and be instructed topracticallyshow the standard method to each stitchingoperator.

Repeated instructions and close followup is utmostimportance in producing the desiredresults.


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DOS & DONTS

Once the operations procedures are set, time and motionstudy must be carriedout.

Economyof motion must be emphasized and dailyproduction targets must be seton its basis.

Balancingof line should be basedon time study( seeguidelines in the chapter on Method Study).

Sampling must be carriedout with the objective tosmoothen and enhance theproduction.

Properplanning and improvements basedon the findings ofpre -production samples ensure less hurdles in productivityand consistent improved quality..


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DOS & DONTS

Use of Dummy

Apart from conformance to the buyers specs. , it is veryuseful

to check the overall fittingof the garmentusing dummy.

Machine Setting

To avoid such problem owing to highertension of the boot, the

operators should always check for suitable machine settings

fordifferent types of fabric.Each operatorshould be provided a piece of fabricof which is

to be run in production and machineperformance should be

checkedon it before sewing theproduction pieces.

It is the responsibilityof Sample Room to initially communicate

the machineparameters to the productionpeople.

stitch machines

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