Stitches-and-Seams - Copy.PPTX

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Stitches and Seams

Gap International SourcingQuality Assurance

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Agenda

§ Stitch components

§ Stitch types

§ Seam types

§ Quality issues


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Stitch Components


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Stitch Components

Thread:§ What types of thread are available, their properties, their ideal

uses and sewing applications

Machine needles:§ Their descriptions and ideal uses

Adequate machinery:§ Machinery that is capable of producing the desired stitch


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Thread Fiber Types

There are two types of thread fibers:

Natural fibers§ Cotton

§ Rayon (derived from cellulose)

Synthetic fibers§ Spun polyester

§ Core spun cotton & polyester

§ Textured polyester & nylon

§ Air entangled polyester

§ Continuous filament (CF) nylon & polyester


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Natural Fibers

Cotton:§ Low Strength per size

§ Low elongation

§ Not as durable as synthetics

§ Colorfastness not as good as polyester

§ Good heat resistance

§ Wrap for core thread

§ Only available in staple

§ Ideal Application:

§ Over dye or garment dye programs

Rayon:§ Medium strength

§ Low elongation

§ Low -wet modulus (low wet strength) i.e. it may shrink or stretch when washed

§ High sheen

§ Only available in continuous filament

§ Ideal application: Embroidery


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Synthetic Fibers

Spun polyester:§ High strength per size

§ High elongation

§ Excellent chemical resistance

§ Good color fastness

§ Good abrasion resistance

§ Good UV resistance

§ Used in most apparel applications

§ Ideal applications:§ Blouses and casual shirts

§ T-shirts with interlock weave

§ Sleepwear

§ Dresses

§ Lightweight twill pants

§ Medium range fleece

§ Sew applications:§ Sews on most types of sewing equipment (lock stitch,chain-stitch, overedge)


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Synthetic Fibers

Corespun§ High tensile strength

§ Excellent chemical resistance

§ Very good color fastness

§ Very good abrasion resistance

§ Very good UV resistance

§ Types§ Cotton wrapped polyester core: Slightly higher purchase price than polyester wrap.Common thread for

all apparel and preferred by jeans makers.Repeated washing of jeans results in some fade down which isalso favored by some jeans manufacturers.

§ Polyester wrapped polyester core: Better color retention than cotton wrap; preferred by most industrialgarment manufacturers due to harsh laundry treatments.

§ Ideal applications:§ Jeans and casual twills

§ Uniforms and Work wear

§ Dress shirts and blouses

§ Sew applications:§ Sews on all types of sewing equipment with minimum sewing problems (lock stitch, chain, overlock, etc.)


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Synthetic Fibers

Textured§ Most economical

§ This thread features high elongation and low cost

§ High bulk thread for excellent seam coverage and seam elasticity

§ Superior thread lubricant that allows it to be sewn with minimum thread tensions

§ Partially translucent so it blends in with many shades

§ Melts when temperatures exceed 480 degrees Fahrenheit

§ Cannot be used in a lock stitch machine for it will fall apart

§ Can snag on rough surfaces

§ Types:§ Textured polyester (mid & regular tenacity)

§ Textured nylon

§ Ideal applications:§ Active wear & fleece wear

§ T-shirts

§ Briefs, panties & lingerie

§ Sew applications:§ Sews on overlock, cover stitch, and chainstitch machines (but no 301 lock stitch)


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Synthetic Fibers

Polyester/nylon continuous filament§ High degree of resistance to abrasion

§ High strength

§ Can de used in heavy duty applications

§ Enhanced ultraviolet ray qualities

§ TypesMultifilament Monocord Monofilament (resembling fishing line)

§ Ideal applications:§ Embroidery which needs to be resistant to enzyme washes for denim

§ Footwear

§ Rain gear

§ Sew applications:§ Can be used on lock stitch machines

§ The monofilament thread can be used in blind stitch operations


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Synthetic Fibers

Air entangled§ High initial modulus for excellent loop formation like cotton

§ Excellent seam durability-high loop strength

§ Excellent seam strength and durability

§ Very good chemical resistance

§ Very good abrasion resistance

§ Very good colorfastness

§ Less expensive than core and spun polyester thread

§ Melts when temperatures exceed 480º Fahrenheit, not as good resistance to needle heat

§ Types§ Polyester

§ Ideal Applications:§ All types of garments

§ Home furnishings

§ Sew Applications:§ Sews on all types of sewing equipment (lock stitch,chain stitch,overedge,etc.)


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Thread Applications and Sizes

Fabric Weight Thread Tex Size

2-4 oz. Tex 16, 18, 21, 24

4-6 oz. Tex 24, 27, 30

6-8 oz. Tex 30, 35, 40, 50

8-10 oz. Tex 40, 45, 50, 60

10-14 oz. Tex 60, 80, 90, 105, 120, 135

Ideal Applications

Underwear,Lingerie,Bathing Suits

Shirts, Blouses T-Shirts, Microfibers

Slacks, Chinos, Jackets

Outerwear, Pants,Etc.

Denim Jeans,Heavy Coats,Leather

Tex Size:§ Refers to a ticket size of sewing thread that is based on the gram weight of 1000

meters of greige (un-dyed) thread

§ Tex sizes are bracketed or rounded off to a smaller size

§ Example: Tex 42 thread would be labeled a Tex 40 thread


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Sewing Needles

§ A sewing machine needle is aslender strand of metal, shaped toprecision that delivers thread to themachine to create a stitch

§ Needles are found in various sizes,and shapes:

§ Needles range in size from very fine60\8 to a heavy duty needle 120/19

§ Most needles use the two numbermeasuring system

§ The higher number relates to themetric system used in foreign

counties which defines the needleshaft diameter in fractions of a

millimeter

§ The lower number relates to thesystem in the U.S and is used toindicate needle shaft diameter


Bent overseam andblindstitch needles

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Needle Point Types

§ Universal: Used for most woven and knit fabrics. Thepoint is slightly rounded, yet sharp enough to piercetightly woven fabrics,yet rounded enough to pushbetween the yarns of a knitted fabric.

§ Ballpoint: Point is slightly rounded. Use for stitching knitfabrics. Helps to eliminate runs.

§ Stretch needle: For stitching knit fabrics that containspandex or Lycra®.

§ Jeans/denim needle: Very sharp point and stiff shank.Used for stitching jeans, canvas and multiple layers.

§ Microtex sharp needle : Sharp point for stitching wovenfabrics, including silk and the newest micro fiber fabrics.Use especially for edge stitching and topstitching.

§ Leather needle : Slight cutting point for stitching throughleather, suede, and vinyl. Never used on woven or knitfabrics.

§ Self threading needle: General purpose needle with slipin threading slot for those who have difficulty threadingneedles.


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Needle Applications and Sizes

Fabric Weight

Light

Medium

Heavy


Needle Size(millimeters) Ideal Applications

65, 70, 75. Underwear,Blouses,Tops

80, 90, 100, 110 Slacks, Chinos, Jackets

110, 120, 140, 160 Denim Jeans,Heavy Coats,Leather

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Sewing Machine Parts

Throat plate

Teeth/feed dog


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Stitch Forming Device

All stitch types are formed with a stitch forming device


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Sewing Machine Parts


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The Process

Thread + Needle + Sewing Machine = Stitches


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Stitch Types


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Stitches

Stitch:

A stitch is the formation of thread for the purpose ofmaking a seam. The elementary basis of sewing is thestitch.

Stitch Type:

A series of recurring stitches of one configuration aredefined as a stitch type.


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Federal Stitch Types

Classification Description Popular Stitches Properties

100 Single Thread Chain Stitch 101 Basting & Button Sewing Least Amount of thread

103 Blindstitch

200 Handstitch Minor Applications,used in couture

and upper end tailoring.

300 Lockstitch 301 Plain Stitch Stitch is used in 90% of garments

Disadvantage: Bobbin W inding

(requires operator to stop and wind)

400 Multi thread Chainstitch 401 Single Needle Flexible stitch,reduces pucker,

406 Coverstitch but can chain off. Highly productive.

500 Serging & Safety Stitch 503 Two Thread Cuts and sews raw edges in one

504 Three Thread Serger operation. Highly productive.

512 Mock Safety

515 Four Thread Safety

516 Five Thread Safety

600 Coverstitch 602 Coverstitch Highly Productive

605 Coverstitch Requires a lot of thread

606 Coverstitch Produces a flat seam that is

607 Coverstitch gentle in contact with the skin.

700 Single thread lockstitch Rarely used stitch


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101 Chain Stitch

Chain stitch:§ Single thread chain stitch:basting

stitch

§ Formed by 1 thread passing throughthe material and inter looping withitself on the underside of the seamwith the assistance of a spreader

§ Ideal application:§ Single thread buttonholes

§ Bartacks

§ Button sew

§ 1 Needle, 1 spreader = 1 thread


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103 Blind Stitch

Blind stitch:§ Formed by 1 thread which inter

loops with itself on the top surfaceof the material

§ The thread passes through the topply and horizontally through portionsof the bottom ply without penetratingthe full depth

§ Ideal application:§ Hemming

§ Waistbands

§ Joining shoulder pads

§ 1 Needle, 1 spreader = 1 thread


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301 Lock Stitch

Lock stitch:§ Formed by a needle thread passing

through the material andinterlocking with a bobbin threadwith the threads meeting in thecenter of the seam

§ Ideal application:§ Topstitching

§ Joining

§ 1 Needle, 1 bobbin = 2 threads


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304 Zig Zag

Zig zag:§ Formed with a needle and bobbin

thread that are set in the center ofthe seam and form a symmetricalzig- zag pattern

§ Also used to identify bar tacking andlock stitch button sewing and

buttonholing

§ Ideal application:§ Underwear

§ Lingerie

§ Decorative stitch

§ 1 Needle, 1 bobbin = 2 threads


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401 Chain Stitch

Chain stitch:§ Formed by a single-needle, 2- thread

chain stitch double-locked stitch

§ Stitch is formed by one needle threadpassing through the materials and interlooped with 1 looper thread that is seton the underside of the seam

§ Ideal application:§ Used for top stitching garment areaswhere flexibility is needed, i.e.: the backrise of a pair of jeans

§ 1 Needle, 1 looper = 2 threads


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406 Cover Stitch

Cover stitch:§ Two needle, 3-thread bottom cover

stitch is formed by 2 needle threadspassing through the material andinter-looping with 1 looper threadwith the stitch set on the undersideof the seam

§ Ideal application:§ Hems on knit garments

§ Any area of a garment that needs astretch stitch

§ 2 Needles, 1 looper = 3 threads


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407 Cover Stitch

Cover stitch:§ Three needle, 4-thread bottom

cover stitch is formed by 3 needlethreads passing through thematerial and interlacing with 1looper thread

§ Ideal application:§ Any area of a garment that needs a

stretch stitch



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503 Two Thread Overlock/Single Purl

Purl overlock:§ Single-needle, 2-thread over edge

stitch formed by 1 needle threadand 1 looper thread forming a purlon the edge of the seam

§ For serging or serge hemmer (blindhemming)

§ Ideal application:§ Serging raw edges



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504 Three Thread Overlock

3-Thread overlock:§ Single needle, 3-thread over lock for

seaming is formed by 1 needlethread and 2 looper threads forminga purl on the edge of the seam

§ For over edge seaming and serging

§ Ideal application:§ To join seams on knit garments

§ Serge raw edges of a seam

§ 1 Needle, 2 loopers = 3 threads


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505 Overlock Double Purl

Overlock Double Purl§ Single needle, 3-thread over edge

with a double purl is formed by 1needle thread and 2 looper threadsforming a double purl on the edge ofthe seam

§ Used for serging only

§ Ideal application:

§ Used in serging raw edges



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512 Mock Safety Stitch

4-Thread/ Mock Safety Stitch§ Stitch formed with 2 needle threads and 2

looper threads with the looper threadsforming a purl on the edge of the seam

§ 512 Right needle only enters the upperlooper

§ Ideal application:§ Used in joining seams and has addedstrength because this stitch will not chain off

§ Can be applied to knits and lightweightwoven fabrics



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514 4-Thread Overlock

Double needle, 4-thread over lock§ Stitch formed with 2 needle threads and 2

looper threads with the looper threadsforming a purl on the edge of the seam

§ This stitch type will chain off

§ Ideal application:§ Used in joining seams on knits where seam

flexability is important



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516 Safety Stitch

5-Thread Safety Stitch§ Combination stitch consisting of

a single needle chainstitch (401)and a 3 thread over edge stitch(504) that are formed

simultaneously

§ Ideal application:§ Joining seams on wovenfabrics, especially medium toheavyweight fabrics



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602 Cover Stitch

Cover stitch:§ 2 Needle 4-thread cover stitch or 2/N

top and bottom cover stitch is formedwith 2-needle threads, a top coverthread and a bottom looper thread

§ Ideal application:§ Stitches used for seaming knit

underwear or athletic wear whichprovides excellent coverage on the topand bottom side of the seam

§ This allows very flat seam constructions

§ 2 Needle, 1 top spreader, 1 bottomlooper = 4 threads


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605 Cover Stitch

Cover stitch:§ 3 Needle 5-thread cover stitch or 3/N

top and bottom cover stitch is formedwith 3 needle threads, a top coverthread and a bottom looper thread

§ Ideal application:§ Flexibility and very flat seaming that can

be used in underwear§ Mostly used in knit applications

§ Decorative stitch§ 3 Needle, 1 top spreader, 1 looper = 5

threads


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606 Flat Lock

Flat lock:§ Formed with 4 needle threads, 1 top

cover thread and 4 bottom looperthreads

§ Consumes a large amount of thread§ More than 24” of thread an inch

§ Ideal application:§ Used in knit applications that require

a flat seam§ Mostly used for joining seams

§ 4 Needles, 1 spreader, 4 bottomloopers = 9 threads


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607 Cover Stitch

Cover stitch:§ 4 Needle, 6-thread flat seam or

4/N top and bottom cover stitch isformed with 4-needle threads, atop cover thread and a bottomlooper thread

§ Also referred to as “Butt” seaming§ Ideal application:

§ The edges of the material are cutand aligned during sewing so thatthe seams feel flat and gentlewhen they come into contact withthe skin

§ 4 needles, 1 top spreader, 1bottom looper = 6 threads


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Inches of Thread per 1” of Sewing** = .050 Seam Thickness & 10 S.P.I

Stitch Type Description Inches of Thread

301 Lockstitch 3.0

401 Single Needle Chain 5.0

406 Coverseam 12.8

503 2 Thread Serger 11.5

504 3 thread Serger 14.5

607 Flatseam 24.2


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Bar Tacking

Bar tacking:§ A reinforcement stitch used in high

stress areas of the garment, or wherethere are multiple thickness, to insurethat the seam will not come apart.


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Buttonholes

Standard straight buttonhole:§ Used on shirts and blouses and

garments made of lighter fabrics

Keyhole buttonhole:§ Used for heavier fabrics and for

garments that will undergo washprocesses such as acid wash, stonewash, etc.

§ A keyhole (shown) is made with gimpand is much stronger than yourstandard straight buttonhole


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301 Split Bar Double Needle Lock

Split bar double needle lock:§ Ideal application:

§ Attaching pockets, it assuresperfect corners


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Button Setting

Button types:§ 2 Hole: Most commonly used on

shirts and lightweight fabrics§ 4 Hole: Mostly used on medium

fabrics to heavyweight fabric

§ “X”: A four hole button attachedin an “x” pattern (consumes

more thread than regular 4 hole)

§ Shank button: Set in with a sideattachment, used on a lot ofcovered buttons and metalbuttons


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Multi Needle

Multi needle machines:§ Ideal Applications:

§ Smocking

§ Attaching elastic

§ Waistbands


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Seam Types


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Seam Types/Government Standards

Seam:§ A series of stitches or stitch types used to join two or more plies of

material together

§ Seams are used for assembling parts in the production of sewn items

§ Seam types for Government standard start with first two lettersdescribing the seams:

§ Superimposed Seams = SS

§ Bounded Seams = BS

§ Lapped Seams = LS

§ Flat Seams = FS

§ Ornamental Seams = OS

§ Edge finishing Seams = EF


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Superimposed Seams

Superimposed seam (SS)§ Formed by placing one ply of

material above another with theedges together and the seamalong one side

§ Most machines can create asuperimposed seam as it is avery basic seam


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Bound Seams

Bound seam (BS)§ Made by folding binding

strips or tape over theedge of the material toreinforce and finish theedge


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Lapped Seams

Lapped seam (LS)§ Formed by overlapping the

material a sufficientdistance and stitching themtogether with one or morerows of sewing


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Flat Seams

Flat seam (FS):§ Formed by joining two

pieces of materials which“butt” together but do notoverlap

§ The edges of the materialare cut and aligned duringsewing


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Ornamental Seams

Ornamental seam types (OS):§ Piping:

§ Uniting a cord or bias trim to a seamto produce a “piped edge”or cordedeffect

§ Fagoting:§ Uniting with a decorative stitch the

finished edges of two pieces offabrics with a space between theedges

§ Saddle stitch:§ Done with special machines

§ Blanket stitch:§ Done with special machines


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Edge Finishing Seams

Edge finishing seams (EF):§ Picot edge:

§ Looks like a crochet edge but it isdone with a sewing machine thatchains and loops the edge of thefabric

§ Serged edge:§ A cut edge of a single ply is

reinforced by overedge stitching toclean finish and prevent fraying

§ Includes other popular methods ofproducing a neat edge like

hemming and blind stitch hemming


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Combination Stitches/Seams

Busted seams:§ 3/thread overlocking the raw edges of the

seams separately, then single needle lockstitch or single needle chain stitch join theseam and press seam open for a flatterappearance

Ditch stitch/crack stitch:§ After joining a seam together with binding,

facing, waistband, or a piece of cloth, if youdo not want the stitch to show on theoutside portion of the waistband, you wouldstitch right through the “ditch”of the seam asto create an non-visible stitch

§ Used frequently in contoured waistbands


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Seam Engineering

Characteristics of properly constructed seams:§ Seam Strength

§ Seam Stretch

§ Seam Durability

§ Seam Security

§ Seam Appearance

Factors that influence all of the above:§ Stitch Type- the more thread required for a stitch type the stronger the seam.

§ Stitches per inch- the more stitches per inch the stronger the seam.

§ Thread Tensions- Tighter tensions result in weaker seams.

§ Thread type and size- the stronger the thread the stronger the seam.

§ Seam type: Appropriate seaming according to the fabric and process

§ Fabric type/weight- very important in determining seam appearance and durability


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Quality Issues


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Seam Quality Issues

§ Seam puckering

§ Skipped and improper stitches

§ Broken stitches

§ Seam grin

§ Seam slippage

§ Needle damage

§ Needle heat


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Seam Quality Issues

Seam puckering causes:§ Uneven ply feeding

§ Incorrect thread tensions§ Incorrect thread or needle size§ Machine threaded incorrectly§ Too many stitches per inch

Corrective actions:§ Ensure presser foot pressure is as light

as possible according to fabric§ Needle tensions kept low

§ Use finer needles§ Use low elongation threads


Skipped Stitches Causes:§ Timing of looper or hook is incorrect§ Needle size too big for thread used

§ Needle vibration§ Needle crooked or bent

§ Loose bobbinCorrective Actions:

§ Rotate needle slightly so it throwsthe needle thread loop into the

looper§ Check machine setting and thread

tension§ Try larger needle size

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Seam Quality Issues

Broken stitch causes:§ Incorrect thread usage (using a low

elongation thread on a knit fabric orwrong tex size)

§ Harsh after treatments such asstone washing on heavy denim

jeans (banding appears to be worstarea affected)

Corrective actions:§ Use of a more flexible thread for the

operation

§ Run loose stitch so stitch rolls ratherthan pop during contact with stones

or enzymes


Seam grin causes:§ When two pieces of fabric are joined

in a plain seam and strained at rightangles, it may open and reveal agap between the two pieces offabric.

Corrective Actions:§ Adjust stitching tensions

§ Increase stitches per inch

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Seam Quality Issues

Seam slippage causes:§ Slippage occurs when the fabric at

either side of the stitching distortsand the fabric yarns slide away fromthe seam resulting in a permanentgap within the fabric seam

Corrective Actions:§ Increase seam allowance

§ Change seam type

§ Increase or decrease SPI dependingon fabric

§ Cut on a bias, where applicable


Needle Damage causes:§ When sharp needle point is used the

needle cuts the yarns causing holesin garment or unraveling

Corrective Actions:§ Use as fine a needle as possible

§ Ball points are preferred.§ The ball should be large enough to

spread the yarns apart rather thansever them

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Needle Heat

Causes of Needle Heat:§ Dense fabric

§ Solution: Add fabric softener/lubricant

§ Needle Damaged or Blunt§ Solution: Change needle, use teflon coated needle.

§ Needle Eye to Small§ Solution: Use finer thread size

§ Sewing machine is running too fast§ Solution: Slow down sewing


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Khaled Ali Gap QA

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