garment mfg

8/4/2019 Garment Mfg

http://slidepdf.com/reader/full/garment-mfg 1/7



Effect Of Stitches, Spi & Sewing Threads On SeamStrength & Slippage On Fabrics

By: Anita A Desai

Assistant Professor & Department Incharge, Department of Textile Technology,Sarvajanik College of Engineering & Technology, Surat.

INTRODUCTION.

Garment manufacturing is the technology of converting 2 dimensional fabric into 3 dimensional fabric. Thegarment industry has become a high profile industry with lots of emphasis on the properties of garments.The properties of garments during wear are related to the type of fabrics used, the stitches employed andalso the types of threads use. This paper reviews the Seam strength and Seam slippage of fabrics. Differenttypes of stitches and different types of sewing threads and their affect on the above mentioned propertieshave also been reviewed.

SEAMS

WHAT ARE SEAMS?

It is necessary to define the term seam at an early stage in any discussions because its application isbroarder than is generally realised. In common parlance, a seam is join between two pieces of fabric.Indeed, this was the assence of the British Standard definitions of seams as contained in the 1965 version of BS 3870: schedule of stitches, seams and stitchings. The noun “Stitching” then apply to situation wherethere is only one piece of fabric, such as when fabric edges are neatened or hems created, and wheredecorative sewing is involved.

The current BS 3870: Part 2: 1991: Classification and Terminology of seam types and the earlier 1983editon, define a seam as “ the application of series of stitches or stitch type to one or several thickness of material”. Thus the term includes virtually all sewing that goes into the garment. Perhaps in the future, thefurther development of non sewing methods seaming will cause this defination to be altered, but the currentdefinition is appropriate to present the purposes.

SEAM QUALITY DEFECTS AND REMEDIES.

Seam Failure - Seam Slippage

DESCRIPTION:

Where the yarns in the fabric pull out of the seam from the edge. This often occurs on fabrics constructed of continuous filament yarns that are very smooth and have a slick surface. Also caused by loosely constructedfabrics.

MINIMIZING SEAM FAILURES – SEAM SLIPPAGE:

1) Consider changing the seam construction to a French seam construction.2) Increase the seam width or width of bite.3) Optimize the stitches per inch.4) Contact your fabric supplier.



SEAM PROPERTIES.

Seam Strength:

A measurement of the load required to rupture a seam. Wovens are tested using “jaws" method and knitsare tested using a "ball-burst" test method.

The five major contributors to seam strength include:-1. Fabric type and weight.2. Thread type and size.3. Stitch and seam construction.4. Stitches per inch.5. Stitch balance.

Any one of these factors can adversely affect the performance of a sewn product depending on the end-useof the sewn product.

Estimating Seam Strength on Woven’s:-

Below are two formulas that were developed for estimating the seam strength on woven fabrics.To do the calculations, you need to know the following:

• Stitch type (301 Lockstitch or 401 Chainstitch)

• Thread Strength (Single-end breaking strength of the thread, measured in pounds)• Stitches per inch

SEAM SLIPPAGE:-

Seam slippage is to test whether the yarn across the woven fabric does not come out from the seam of agarment when a force is applied on them. It is also used when a breaking force of rupture, a minimumelongation, or both are required to determine the sewn seam slippage, or seam integrity of a fabric for aspecified end use. Seam slippage occurs when the density of the fabrics or the construction is low, less warpand weft per inch.

STITCHES.

WHAT ARE STITCHES?

British Standard 3870: Part 1: 1991: Classification and terminology of Stitch Types, is the standard referenceto the wide range of stitch types now available for use in garment construction. It defines a stitch as: “oneunit of confirmation resulting from one or more strands or loops of thread intralooping, interloping or passinginto or though material”.

Intralooping is passing of loop of thread through another loop formed by the same thread.

Interlooping is the passing of loop of thread through another loop formed by different thread.

Interlacing a term also used in relation to certain stitches is the passing of the thread over or around another thread or loop of another thread.A series of recurring stitches of one configuration is defined as a stitch type.BS 3870: divides many types which are available into 6 classes which variously covers the demands of



joining fabrics together, neatening raw edges, or providing decorations, or offer the economy of doing morethen one of these at a time.

SEWING THREAD.

THREAD CONSTRUCTION:-

Air Entangled Thread

Is made from continuous filaments of polyester that are entangled as they pass through a highpressure air jet. This yarn is then twisted, dyed,and wound on cones with lubricant. Air entangled threads are used in everything fromseaming flags to heavy denim jeans. (Exampleproducts are Magic®, Signature® Plus, andSignature Machine Embroidery™.)

Core Thread

Is made by spinning a wrap of staple cotton or polyester around a continuous filament of polyester fibers. Afterwards, two or more of these single yarns are twisted together to formthe thread. Core threads have fuzz on their surface giving them good lubricitycharacteristics and also a continuous filamentcore that contributes to high strength anddurability. When wrapped with a cotton wrap, core threads have very good needle heatresistance. When wrapped with a polyester wrap, core threads have excellent chemicalresistance and colorfastness. Core threads are used in everything from fine blouses toheavy coveralls and overalls. (Example products are: D-Core® and PermaCore®.)

Monocord Thread

Is produced from continuous filaments of nylon

that have been bonded together. They have verylittle twist so that they look like a single cord of yarn. Because of the way these threads aremade, they appear to be flat and ribbon-like,which provides a high degree of resistance toabrasion. Monocord threads are exceptionallystrong for their size so they are used in themanufacturing of furniture, shoes, and other heavy duty applications. (Example products are Anecord®, Anequilt®, and TerylB™.)

Monofilament Thread

Normally produced from a single nyloncontinuous filament resembling fishing

line. Usually monofilament threads are usedbecause the thread is translucent and blends inwith many colors. Because it has a tendency to be stiffer than other filament products, itis not recommended for seams that may lay adjacent to the skin. Also, because it is asingle filament, it may unravel easily if the thread is not locked in the seam adequately.Monofilament threads have been used in quilting operations on quilts and bedspreads,as well as, in blindstitch operations on drapery and apparel. (Example product isClearlon®.)



3.2. THREAD BRAND LEGEND:-

Spun Thread

Is made from cotton or polyester staple fibersthat are spun into single yarns and then two or more of these yarns are plied to make a sewingthread. Spun threads have fuzz on their surfacinggiving them a soft hand and good lubricitycharacteristics. Spun threads are used in everything from women's lingerie to heavy

leather gloves. (Example products are: Anecot®, Anecot Plus®, DuPont™ Kevlar®,DuPont™ Nomex®, Endurance™, Excel™, Spun Kool®, and Perma Spun®.)

Textured Thread

Is made from continuous filaments of polyester or nylon that have been textured by pin, disc, or beltand then heat set to insure proper bulkretention. Textured polyester is usuallymanufactured with regular or mid tenacity,continuous filaments depending on the application. Textured threads are ideal for overedge, chainstitch, and coverstitch of the finished seam and offers good seamelasticity. Textured threads are usually less expensive when compared to other thread

types. (Example products are: Best Stretch®, Tex Kool®, and Wildcat Plus®.)

Twisted Multifilament Thread

Is made from continuous filaments of polyester or nylon that are twisted together into a cohesivebundle and then plied to make the thread. Theyare then dyed, stretched, and heat set to achievethe desired physical characteristics. TwistedMultifilament threads are available either soft or with an additional bond for better plysecurity and abrasion resistance. They are exceptionally strong for their size and theyhave excellent resistance and durability. These threads are used for seamingeverything from bathing suits to automobile upholstery. (Example products are: Anefil

Nylon®, Anefil Poly®, Anefil® Stx, Cocoon Performance Bobbin®.)

Twisting

The above types of thread constructions that involve twisting (suchas spun, core, and twisted multifilament) are twisted in the followingdirections:"S" direction or right twist for single strand yarn (such as spun)"Z" direction or left twist for ply yarn (such as core and twistedmultifilament)



2.3.3.THREAD SIZE COMPARISION:-



The top-feed dog has been designed so that theoperator can smoothly place the material to besewn on it. Furthermore, the gauge can be easilyreplaced and stitch adjustment can be performedwithout difficulty.The machine comes with aforced lifting mechanism for the top-feed dog.This enables the operator to place the materialto be sewn on the top-feed dog moresmoothly.The machine incorporates its exclusivechain-off thread presser pedal foot, whichimproves seam quality and ease of operation.The exclusive gauge comes in fivedifferent types, and the gauges can be replacedin a simple procedure.This facilitates therequired adjustment when changing the needlecount.The machine is also capable of performingpartial shirring.The machine works effectively for processes which require partial shirring as longas the partial shirring device (PH-3) is used in

combination with the partial shirring dial.The partial shirring device comes in two different types, the kneepaddrive type and,the pedal drive type.The machine comes with many different,functions to prevent unevenmaterial feed and puckering for higher-quality seams.The machine incorporates many functions and placesa great deal of importance on higher product quality.The machine is adaptable to a wider variety of light-to

heavy-weight materials and takes full advantage of top-feed mechanism.This enables unskilled operators tofinish seams of consistent quality.

Summary:

Thus the importance of Seam strength and Seam slippage of fabrics has been clearly studied for thegarment manufacturing process. A thorough knowledge of different types of stitches and different types of sewing threads and their affect on the above mentioned properties is required for the garment manufacturingprocess.

garment mfg

Documents