Sunday, February 10, 2013

Essay on Sewing needle ( Textile Technology)


         Sewing Needle

 

A sewing needle is a long slender tool with a pointed tip. The needle must be able to penetrate the material being sewn, by pushing the yarns aside according to the application, without damaging it. Modern needles are manufactured from high carbon steel wire, nickel or gold plated for corrosion resistance.

      Needle Points

Needles are manufactured with a wide variety of needle points appropriate for the different properties of materials which have to be sewn. The needle point can be located wither centrally or eccentrically. There are two basic classes of points:
§  Round points
§  Cutting points
Slim Set Point Needles – can be penetrate the yarns of the material being sewn through its sharp point and is ideal for all woven fabrics because it helps to produce an even stitch and causes a minimum of fabric puckering. They are used for Blind stitches and for fine, densely woven fabrics. These points are not suitable for knitted fabrics.

Set Cloth Point – needles are slightly rounded to displace yarns of the material being sewn without damaging them. This is most commonly used point.

Heavy Set Point – needles are strongly blunted. These are used for button sewing machines.

Ball Points – Light Ball Point is used for sensitive fabrics such as knits, to prevent damage to the loops. This is crucial for maintaining the fabric’s elasticity. Medium ball point and heavy ball point are used for fabrics containing stretchable yarns. While sewing the threads are displaced not pierced. The needle pushes between the fabric yarns rather than “cutting rough” the yards.

Cutting Points – are used for sewing leather, coated or laminated fabrics. These are classified and named according to the position of the cutting edge and its shape. The shapes are named with regard to the form of the cutting edge for example spear point, triangular point, diamond point etc. The shape of this needle will create a slit (rather than a large hole) through which the thread will pass.

 

 Needle sizes

Suitable sewing needle type is one of the most important parameters for ensuring the effective and fault free sewing process it will depend on the characteristics of the needle type, needle point, needle fineness, fabric material, the size of sewing thread, the seam type and stitch type.
It is important to use correct needle size for the type of fabric being used. The metric size “Nm” of a needle defines the diameter of the blade (in 1/100 mm) at a point just above the scarf. Fine needles are around Nm 70, medium needles are abound Nm80-Nm90 while thicker needles are around Nm100. The convention for sizing is that the length and thickness of a needle increases as the size number decreases. Delicate fabrics such as silk, chiffon, voile, fine lace and organdie would need a fine “size 9” needle. Lightweight fabrics such as synthetic sheers, taffeta, velvet, stretch fabric and tricot would need a “size 11” needle. Medium weight fabrics such as poplin, linen, chambray, wool crepe, flannel, knits, jersey, wool and satin would need a s “size 14” needle. Medium-heavy weight fabrics such as sail cloth, gabardine and tweed fabrics would need a “size 14-16” needle. Heavy fabrics such as denim, upholstery and canvas fabrics would need a “size 16-18” needle. Most readily available machine needles are sized from 9 to 18. The smaller the number, finer the needle.

Essay on Stitch types ( Textile Technology)


      Stitch Formation and its Uses 

 

Stitch Type
No.
Formation
Characteristics
Application
Single thread chain stitches
101
One needle thread intralooping with itself
elastic, easy to unravel
basting, buton sewing, label setting, back closing , tacking
103
use a curve needle to penetrate the fabric surface but stitich does not show on the face
invisible on garment surface
hemming of pants and skirts
Hand stitches
200
Done by hand with one needle thread
Flexible use
Basting on tailored jackets
Lock Stitches
301
interlacing of needle thread and bobbin thread
reversible, strong, versatile, secure,neat flat but not stretchable
top stitching, common seam sewing
304
similar to 301 but in a zigzag pattern
similar to 301 but stretchable
attaching elastic/lace to lingerie decoration
Multithread chain stitches
401
one needle thread and one looper thread, interlooped and interlaced together
continuous running, strong, duarable, extensible, thick and can be unravelled
waist bands, inseam of jeans, side seam/sleeve seam of shirts, rainwear
402
a looper thread travels betwen two needle threads on the underside of the fabric and form a ridge
for stimulative effect
stimulate permanant crease on the knitted pants and cording backs of gloves
402
similar to 401 but zigzag pattern
higher elasticity than 401
attach waist band lining to men's trousers
406
similar to 402 but does not ridge up
concealed raw edges on the underside to produce a flat and comfortable seam
cover seaming, sewing belt loops,binding and attaching elastic to underwear,hemming t-shirts and sportswear
407
similar to 406 but with 3 needle threads and one looper thread
high elasticity , stronger and better coverage effects
attaching elastics to briefs, panties and undergarments
Overedge Stitch
501
one needle thread interlooping itself warps and protects the edge
ealstic , allow the seam to break open, easily unravelled
break open seaming
502
formed by 1 needle thread and 1 looper thread
Stronger than 501
bag seaming
503
similar to 502 but the needle thread interlocks with the looper threads on the edge of the plies
better edge coverage than 501 and 502, highly elastic
thin surging on thread,blind hemming on T-shirts
504
one needle and 2 looper threads interlock on the edge of the plies
higher extensible, tighter structure, prevent fraying but bulky and easily runback
popular serging and seaming of knit garments
514
formed by 2 needle thread and 2 looper threads
produce a wider bright than 504, strnger and more elastic
strong seaming of knits and woven fabrics
Cover stitch
602
similar to 406 but it has a covering thread on the top surface
provide excellent top and bottom cover and flat seam
attaching knit collar on kint garments
605
similar to 407 but it has a covering thread on the top surface
better coverage than 602
cut edge bining , elastic attaching
607
similar to 605 but it has 4 needle threads, 1 cover and 1 looper thread
flat, stretchy and smooth trims and seams simultaneously
flat, butted seams on breifs and panties