Sewing Needles used in Sewing machine

7/30/2019 Sewing Needles used in Sewing machine

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Needle;Sewing needle is the thin metal substance which is used for penetrating fabric and joining various

parts of fabrics according to specified design to create garments. Sewing needle has a direct effect on

seam strength, appearance and wearability.The Needle movement is related to the

Types Of Needles:There are two types of Needles as discussed below:

1) Hand Sewing Needle:Hand sewing needles should be large enough to carry the thread through the fabric without

breaking the thread or tearing the fabric. Common dressing sewing needles are known as

Sharps.

Properties of Hand Sewing Needles:

Hand Sewing Needles should posses the following properties:

a) Sewing Needle:Sewing Needles should be long and must contain a standard size.

b) Embroidery Needle:Embroidery Needles should be round and pointed.

c) Darning Needle:2) Machine Sewing Needles:

Machine Sewing needles should capable of performing multipurpose functions according to

the size of the fabric and thread size.

Properties of Machine Sewing Needles:

Machine Sewing Needles should posses the following properties:

a) Cloth Point Needles:Cloth point needles are such type of machine sewing needles which are used for

sewing fabrics containing gaps in their structure.

Properties of Cloth point Needles:

1. These needles are used for sewing textile Materials.b) These are used for sewing textile materials rather than the sheet material already

described. The points have a round cross section.

The needles are different for the various woven and knitted fabrics.

Knitted fabrics consist of yarns with spaces between them and if a yarn in a knitted fabric

is broken the knitted structure may begin to unravel. The requirement in sewing knitted

fabrics is :

a. A needle which will slightly deflate the yarns and enter the spaces.

b. A needle of as small a size as possible consistent with needle strength and sewing

thread size.

c. A fabric which is sufficiently lubricated that it has flexibility in relation to the

movement of the needle.


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The shape of the tip of the neele point which best achieves this deflation is a ball shape

and the needle is referred to as a ball point needle.

Woven fabric consist of yarns which can have greater or lesser amounts of twist,

interlaced with each other at various degrees of density.

For that a needle is needed that goes between the fibres and does not strike and break

them.

The shape of the tip of the needle point which best achieves this penetration between the

fibres has the appearance of being slighly cone shaped. It is usually referred to as a set

point needle.

c) 0 commentsd)e) Needle Point

These are divided into two parts- Cutting points and cloth points.

Cutting Points: These are needed for fabrics like leather where there are no gaps in the


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structure.

Cloth Points: These are needed for those fabrics where there are gaps in the structure.

Cutting point Neeedles

a. Wedge Point: It produces most durable seam on leather. It resists great stress, the


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incision lie at right angle to the seam direction and high stitch density can be achieved.

b. Cross Point: Here strength is considerably weakened. The material is likely to tear if

stress is at the right angle. The incisions lie parallel to the direction of the seam.

c. Twist Point: The strength is intermediate and the incisions like 45 deg. to the direction

of the seam.

Cloth Point Needles

Multipurpose machine needles

3) are suitable for regular machine4) sewing. These are available in5) sizes to suit the fabric and thread6) being stitched. European sizes7) range from 60120 and8) American sizes from 920.9) Needle packets are usually10) numbered with the relevant size.11) The larger the number, the larger12) and stronger the needle.

Sewing Problems

1. Problems of stitch formation

It gives rise to poor seam appearance and performance

These are

- Slipped stitches- Staggered stitching

- Unbalanced stitches

- Variable stitch density

- Puckering

- Needle, bobbin or loops thread breakage

a. Slipped Stitches

Arise from the hook or loopes in the machines not picking up the loop in the needle thread.

b. Staggered Stitches

Can be caused by yarns in the fabric deflecting the needle away from a straight line of stitching, giving a poorappearance.

c. Unbalanced stitches

It can reduce the potential of stretch in a seam in a knitted fabric and may lead to seam cracking.

d. Variable stitch density

It arises from insufficient foot pressure in a drop feed system, causing uneven feeding of the fabric through the

machine.

PROBLEMS OF PUCKER


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Pucker is a wrinkled appearance along a seam in an otherwise smooth fabric. It generally appears as if there is too

much fabric and not enough thread in the seam.

Causes of Pucker

a. Seam pucker due to differential fabric stretch

Remember that the upper fabric would tend to move forward by an amount always less than the movement of lower

one. This is due to the fact that the lower layer is positively gripped by the feed dog and upper layer is driven by the

friction by the lower layer.

b. Differential pucker caused by fabric dimensional instability

The essential feature causing differential pucker is the relative change in dimensions of upper and lower fabric after

the seam has been made.

Differential pucker due to dimensional instability may be suspected when the two fabrics being joined are markedly

different or when one shows noticeably more pucker than the other.

c. Seam pucker due to extension in the sewing threads.

All sewing threads have some extensiblity and they are extended by the action of the tension devices and pass into

seam in an extended state. When removed from the machine they will tend to contract.

When thread extension is proved to be the cause of puckered seam, consideration must be given to the type of thread

being used and to the tensiton settings on individual machines.

d. Seam pucker due to sewing thread shrinkage

Cotton sewing threads increase in diameter and shrink in length when wet and these distortions may cause pucker insensitive fabrics. Synthetic sewing threads have negligible wet shrinkage and should always be used for such

fabrics.

e. Seam pucker due to structural jamming

The presence of the seam itself may introduce a distortion. It is in no way dependent on the action of the sewing

machine, but it invariably appears as soon as the seam is formed.

As soon as a woven fabric has been constructed so as to be close to the practical weaving limit, that is very less

space left between the yarsn either warp or weft ways, it may be extremely difficult to force in any more threads in

either direction.

The term 'structural jamming' is given to this type of pucker because it results directly from the act of jamming extrathreads into a structure which is already too closely set to accommodate them.

Seam pucker due to mismatched patterns

This is due to the discrepency between the lengths of the stitching lines on the pattern pieces that go together in the

seam. Thus there is a difference in the lengths of the cut parts which the machinist is sewing together.

Problems of damage to the fabric along the stitch line

a) Mechanical damage

1. Needles can strike and break fabric yarns and burst the loops in knitted fabrics. For this appropriate set and ball


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point needles are necessary.

2. Needles should always be as small as possible.

3. Sometimes the combination of the machine speed and nature of the fabric prevents the yarns from moving out of

the way of the needle sufficiently fast to avoid damage .To solve the problems either reduce the speed - which

means lesser production or ensure that the fabric is adequately lubricated. It calls for having resin finish on the

fabric.

- All sample lengths of the fabric should be tested for sewability and the necessary finishes should be specified

before the bulk fabric is ordered and bulk fabric should be tested before production to ensure that finishing treatment

has been effective.

b) Needle Heating Damage

Needles heating occurs as a result of friction between the needle and the fabric being sewn.

In high speed sewing of dense material, temperatures as high as 300 deg or even 350 deg can be reached.

At this temperature it is possible that the needle may suffer damage and lose its hardness.

Natural fibres in a fabric or thread can withstand these temperatures for a short time.

With synthetic fibres, the position is more critical since the fibres melt at around 100 deg C, polyamide and

polyester soften at about 230 deg C and polyacrylics will only withstand temperatures upto 280 deg C.

Overheated needes can

- Soften the synthetic fibres

- Weaken them

- Produce rough seam with- harsh stitch holes

Melted fibres stick to the surface of the needes

- Increase its friction

- cog the eye and the groove

- No sew

- Skipped stitches

Reduction of Friction

- Reduce the sewing speed

- Changing the shape or surface of the neede

- long seams will ensure more heat build up in the needle

- Jet of compressed air.- User spun or corespun yarns.

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Sewing Needles used in Sewing machine