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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 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 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

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.

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.

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Size of Needle

Choice of size is determined by the fabric and the thread combination which is to be sewn.

If needle is too small for the thread, the thread will neither pass freely through the eye nor fit properly into the long groove. As a result it will suffer from excessive abrasion. It may result in

Costly thread breakage in production because the machinist must stop to rethread the needle and possibly also to unpick some of the stitching so that a joint does not show in an important part of the garment.

When sewing heavy plies of material, a fine needle tend to get deflated. It can affect the stitch loop pick up and cause slip stitches, or it can even lead to needle breakage

A break in the situation of multi-needle sewing with fabric running through the folders would be impossible to repair.

If the needle is too large, there will be poor control of the loop formation which may cause slipped stitches.

There will also be holes in the fabric which are too big for the stitches and give an unattractive seam appearance.

In closely woven fabric, there will be a pucker along the seam line due to fabric distortion.

Nomenclature for Needle Size

Metric

d x 100 = Metric Number, where d is in millimeter,

eg. For d = 0.65 mm, number of needle is 0.65x100 =65




Selection of needle and thread size for a particular seaming situation is a question of achieving a balance between the minimum damage due to pucker which is a matter of small needle size and seam strength which requires a substantial needle and thread.

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Sewing Machine Needle

The way in which the fabric is penetrated by the needle during sewing has a direct effect on seam strength and on garment appearance and wearable life.

The functions of the sewing machine needle in general are:

a. To produce a hold in the material for the thread to pass through and to do so without causing any damage to the material
b. To carry the needle thread through the material and there form a loop which can be picked up by the hook on the bobbin case

Anatomy of a Sewing Machine Needle



Butt: It is shaped end of the needle which facilitates insertion into the needle bar or clamp.

Shank:
It is the upper part of the needle which is located within needle bar. It is the support of the needle as a whole and is usually larger in diameter than the rest of the needle for reasons of strength.

Shoulder: It is the section intermediate between the shank and the blade.

Blade: The blade is the longest part of the needle down to the eye. The blade is subjected to the greatest amount of material through which the machine passes.

Long Groove: The long groove in the blade provides a protective channel in which the thread is drawn through the material during stitch formation. Sewing thread can suffer considerably from abrasion during sewing as a result of friction against the fabric. A correctly shaped long groove, of a depth matched to the thread diameter, offers considerable protection to the thread.

Short Groove: The short groove is on the side of the needle which extends a little above and below the eye. It assists in the formation of the loop in the needle thread.

Eye of the Needle: The eye of the needle is the hole extending through the blade from the long groove on one side to the short groove on the other.

Scarf or Clearance Cut: It is a recess across the whole face of the needle just above the eye. This ensures that the loop of the needle thread will be more readily entered by the point of the hook.

The Point of the needle is shaped to provide the best penetration of each type of material.

The Tip is the extreme end of the point which combines with the point in defining the penetration performance.

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Seam Types

Stitched seams are divided into eight classes according to the type and minimum number of components within the seam.

These components which can be the main fabrics of the garment or some additional items such as a lace etc, are termed as being of 'limited' or 'unlimited' width.


where a component is referred to as being limited on one side, that side might be the cut edge of the garment piece that is being seamed.

Where a component is referred to as being unlimited on one side, that edge might be the far edge of the garment panel irrelevent to the seam under consideration.( Figure-1)



Class-I (Superimposed Seams)

It is produced with a minimum of two components both limited on the same side. A variation of the superimposed seam is the french seam.



Class-II ( Lapped Seam)

Seams in this class are produced with a minimum of two components but with these, one is limited on one side and the second is limited on the other side. The components are opposite and at different levels and overlap each other.

Class -III ( Bound Seams)

In this class, seams are produced with a minimum of two components , one is limited to one side with the second is limited on both sides.

Class-iV (Flat Stitching)

In this class, seams are produced with a minimum of two components of which one is limited on one side and the second on the other. The two components are opposite and on the same level. These seams are referred to as flat seams because the fabric edges do not overlap. They may be butted together without a gap and joined across by a stitch which has two needles sewing into each fabric.

Class-V (Decorative Stitching)

Seams in this class are produced with a minimum of two components unlimited on two sides. Any other component is either limited on one side or limited on two sides.



Class-VI (Edge Neating)


It is produced with only one component limited on one side (either on the right or the left). Seam types in this class include those where fabric edges are neated by means of stitches as well as folded hems and edges.