Service & TechnologyInfo rma t ion fo r t he sew ing i ndus t r y

AMANN sewing threads for shoes and leather goods

1000

34G

B020

0002

9

Service & Technology

Today, shoes are almost exclusively stitched with synthetic sew-ing threads. For this, mainly polyester or polyamide continuous filaments are used. AMANN's Serafil thread has become the stan- dard among polyester continuous filaments and has been used successfully for years.

Serafil Polyester continuous filamentSerafil is used as a synonym for sewing threads made of sturdy hard-wearing high-strength polyester continuous filaments. Its advantages are convincing:

• Outstandingsewability• Excellenttensilestrengthandabrasionresistance• Well-balancedglidingperformance• Goodresistancetoacids(forexamplesweat)• Goodresistancetosunlightandweather• Broadrangeofarticlesandcolours• Brilliantseamappearance

Serafil's reliable sewability and universal performance characteris-tics guarantee high quality standards in shoe production.

Serafil features two special threads in its product range:

• ThebondedversionSerabond–designedspecificallyformulti-directional sewing with automated lockstitch machines

• Thewater-repellentSerafilWR(WR=waterrepellent)

Quality threads for shoes and leather goods

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ONyx Polyamide 6.6 continuous filamentONYX, a continuous filament made of polyamide, is the first-choice alternative to polyester continuous filaments.ONYX is a robust sewing thread made of abrasion resistant polyamide 6.6 continuous filaments and impresses with its:

• Excellentsewability• Superiortensilestrength• Outstandingabrasionresistance• Well-balancedslippage• Brilliantlook

TheONYXticketnumbers30and40arealsoavailableinwaterrepellentquality(WR).

Boththreads,SerafilaswellasONYX,havecarefullyappliedsurfacefinishes(lubrication)toguaranteethatthethreadsmoothlyglidesthrough all thread guides of the sewing machine. This finish provides both sewing threads with even more quality features:

• Highthermalresistanceduringthesewingprocess• Anti-staticproperties• Bestpossiblesewingcharacteristicsthroughhighlycompact

threads

ThesmoothsurfacesofSerafilandONYXareappreciatedevery-where where silk-type shiny seams are required.

Duetotheircompactness,SerafilandONYXfeaturebestsewingcharacteristics and prove their high performance on multidirectional automated lockstitch machines.

Serafil ticket no. in comparison

Sera

fil 10

Sera

fil 15

Sera

fil 20

Sera

fil 30

Sera

fil 40

Sera

fil 60

Sera

fil 80

ONYXticketno.incomparison

ONYX10

ONYX13

ONYX20

ONYX30

ONYX40

ONYX60

ONYX80

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Serabraid Braided polyester continuous filamentSerabraid, the polyester braided thread, is available in the following sizes: 800, 1000, 1200 and 1400. These ticket numbers represent their optical diameter: Serabraid 800 has an optical diameter of 0.8 mm; Serabraid 1000 has an optical diameter of 1.0 mm, etc.

Depending on the application, Serabraid is available in three different finishes:

• T60(slightlywaxed,suitableformachinesewing)• T90(heavilywaxed,suitableforhandsewing)• WR(waterrepellent)

Braided threads feature a special braided look and are especially suited for decorative seams. Further, due to their construction they have excellent tensile strength and abrasion resistance.

Sewing thread raw materials Serafil, SabaCandthebearingcoreofRasantaremadeofhigh-strength polyester filaments which are instrumental to their high seam quality and most effective functional value. Because even the raw material of high-strength polyester features excellent tensile strength and abrasion resistance, shoe seams will withstand even the toughest challenges for a long time.

High-strength polyester features high resistance to universal chemi-cal influences. Compared with other conventional sewing thread raw materials Serafil and SabaC raw materials are the best for with-standing the harmful effects of UV radiation and a large number of acids.

Due to their higher specific weight compared to polyamide sewing threads of the same ticket number, polyester sewing threads have finer diameters; the thread is thinner. This allows the use of thinner needles which reduces the needle heating and improves the look of the seam; risk of perforation is reduced when cutting needles areusedandconditionsforsealingareimproved.Ofallsewingthread raw materials, polyester incorporates the most advantages and has therefore gained the widest acceptance in a broad range of applications.

ONYXismadeofpolyamide6.6filamentsthatmaybeusedasanalternative to high-strength polyester. Although polyamide does not feature the universal characteristics of polyester, it is superior with respectstotensilestrengthandabrasionresistance.ONYX'smainfield of use is in items where the raw materials characteristics must be in line with the requirements of the product. This may be required, for example, for sport footwear and trekking shoes.

In addition to our continuous filaments, our polyester/polyester and polyester/cotton corespuns are also important threads in the shoe and leather processing industry.

SabaC Polyester/polyester corespun Rasant Polyester/cotton corespunSabaCandRasantarepowerfulcorespunthreadsmadeof100%polyester or polyester with cotton coating that are used in specific applications in the shoe and leather industry. Due to their textile sur-face they are an alternative to the smooth continuous filaments.

• AsbobbinthreadinlockstitchseamscombinedwithSerafilasneedle thread

• Asaneedlethreadinzigzagmachines• Forthebestpossibleadhesionofthestitchestotheshoelining• Fortextileslippers• Forsewingofbootliningswithflatlockoroveredgestitching

machines• Saba8andtheRasantticketno.11and15forrustictopstitches

I-tech 20

Polyamide 6.6 continuous filament with metalcomponents(inox)I-tech 20 is a polyamide-based conductive continuous filament with apolyester inoxcomponent (polyester/stainless steel). Themetalcomponentdeflectselectricity(anti-staticsewingthread);thereforeI-tech 20 can be used in safety shoes.

© Groz-Beckert KG

Service & Technology4

ColoursSerafil,ONYX,SabaCandRasantaredyedusingahigh-tempera-ture process with high-quality dyestuffs. This and the development of a great variety of colour formulas make the Serafil colour range extremely varied. All nuances offered feature the same high colour fastness, an even colouring for each batch and a brilliant silk-like look–aplusforalldesigners.Duetoourwell-sortedandpreciselycoordinated inventory system, this wide colour range is practically availableJust-in-Time(JIT).

OneexampleforthisextraordinarycolourvarietyisthecolourcardforthecoarseSerafilqualities(colourcardno.22)listingmorethan100 colours.

ElasticitySerafil, SabaC,RasantandONYXaredesignedtomeetmaximumsewing performance as regards force elongation behaviour and elasticity, whereby the different raw material characteristics are accounted for through different process control flows.

Serafil–themostimportantsewingthreadforshoesandleathergoods–offersaspecificallywell-balancedstrength-elasticityratio.This provides ideal conditions for precise stitching at the sewing machine. A correctly set thread tension makes a well-balanced stitch. This provides the basis for superior seam tear resistance and elasticity. Neither the lasting of the upper nor heavy wear can harm Serafil seams.

Thermal resistanceThe melting point of approx. 250° C for Serafil, SabaC,RasantandONYXfarexceedstemperaturesallowableforleatherintheshoeand leather processing industry. Because polyester, for example, begins softening right below itsmeltingpoint –about 235°C– temperatures that are applied only briefly while ironing or blow-drying have no affect on the seams.

Needle temperaturesIn addition to producing the desired stitch pattern, needles with dif-ferent cutting point forms facilitate penetration of the material layers. The usual needle temperatures generally do not affect AMANN's synthetic sewing threads.

Serafil, SabaC,RasantandONYXarefinishedwithaspecialprotec-tive finish that not only provides for improved gliding performance of the sewing thread but also reduces the needle temperature at the eye.Inexceptionalcases,theuseofthreadlubricant(forexamplesiliconeoil)orapreciselycalibratedmachineaircoolingsystemmaybe an alternative.

AMANN thread lubricator that is best positioned just before the sewing thread enters the needle provides cooling for the needle and keeps it clean; it also simplifies penetration of the needle and the thread passing through the needle.

➀= Needlepoint(upperdeadcentreoftheneedle)➁= Needleeyeatpenetration(areabelowtheneedleeye)➂= Needleeyeatpenetration (areaabove theneedleeye)

Maximum temperature➃= Needleshaftatpenetration(reinforcedarea)➄= Transitionfromneedleshafttoneedleshank

Withhighneedletemperatures,syntheticorfoamedshaftmaterialscan start melting in the stitching hole. This leads to needle deposits that may become encrusted on the needle shaft. This affects the stitch forming process and the needle temperature rises even more due to the increased friction which may lead to thread breaks. In such cases needle temperature must be reduced, for example by using a slimmer needle, reducing machine speed or through an air cooling system calibrated for the needle.

Encrustedneedles

The diagram shows how friction between needle and material affects the needle temperature

Nee

dle

tem

pera

ture

Needle path

➀

➄ ➃ ➂ ➁ ➀

➄

➃

➁

➂

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Thread guides and unwinding from the coneIt is important that the spool below the thread guiding eye of the thread stand is centred exactly and guidance through the thread guiding elements of the thread holder as well as the sewing machine is faultless.

AMANN king spools for Serafil andONYX are equipped withgrooves to catch loose thread layers. In addition we recommend using spool trays no. 5 or 6.

WhensewingwithSabaCandRasantcones,useofAMANNspooltrays number 2 is recommended to safely catch any layers falling offtheconeandtoensureitsuprightposition.Onitswaytotheneedle, the sewing thread should pass through the guiding elements as directly as possible. The lower the number of thread redirections, the more exactly the thread tension in the thread tension element necessary for forming the stitch is defined. If the thread is redirected too often between spool and thread tension element uncontrolled tension may occur. This may lead to peak tensions resulting in an irregular stitch pattern and thread breaks.

Determining sewing thread consumptionFor a rough overview you may use the table below; it is based on our experiences in the area of shoe production: Allowances for beginning and end of seam or colour changes are already included in these values.

Seam elasticity and seam stabilityIn general, the same and correct thread size must be used for needle and bobbin threads in all holding seams. This ensures optimal cross tensilestrengthandelongationoftheseam.Occasionally,peopleaskfor a thinner bobbin thread, either to better utilise the spool capacity or to achieve a less prominent seam on the inside of the shoe. Since a weaker bobbin thread automatically reduces the seam's cross tensile strength, one needs to check whether the resulting stability will still meet the requirements.

If the material allows so, high stitch densities should be used for highly stressed seams. This increases both, the seam's cross tensile strength and also its elasticity. However, keep in mind that the risk of perforating the leather grows with increased stitch density. This risk is especially high if needles are used where the cutting direction matches the sewing direction.In order to maintain a high stitch density, only needles with a more favourable cutting direction should be considered.

The following diagram shows the elasticity of seams with different stitch densities. The fact that bagging or staying seams are usually highly stressed attaches special importance to the seam elasticity. This seam elasticity can be achieved by maintaining a material-specific high stitch density.

Favourablethreadguiding(example)

Sewing thread consumption standard values

Thread size Standard value Range

Men's shoes (elegant)Men's shoes (athletic)

Men's boots Lady's shoes (elegant)Lady's shoes (athletic)

Lady's boots

21 m 26 m 33 m 26 m 26 m 33 m

17-28 m 23-30 m 28-40 m 23-30 m 23-30 m 25-45 m

Service & Technology6

Sewing parameters

Material: Two-ply soft leatherMaterial thickness: 2.4 mmSewing thread: Serafil 60Stitch type: 301

This direct relationship of stitch density to seam elasticity shows how much seam stability and durability depends on the machine set-tings.

Decorative seamsYouhaveachoiceofafullrangeofSerafilandONYXticketnumbersforglossysilk-typeseamsandSaba8andRasant11and15forrusticand thick decorative seams. For special decorative seams, Serabraid, a polyester braided thread, is the first choice.

It is extremely important to choose a bobbin thread that is not too fine for robust decorative seams. A rule of thumb is that the bob-bin thread should be no more than one ticket number finer than the needle thread. Greater differences between needle and bobbin thread require extreme bobbin thread tension to ensure that it won’t be drawn up and become visible on the upper material. The bobbin thread that is usually shorter in decorative seams on leather is then stretched extensively and may possibly no longer feature sufficient tensile strength during the lasting process. Broken decorative seams can therefore be the unpleasant result of an incorrect bobbin thread ticket no.

Zigzag seams

Swinging needle bar movements when sewing zigzag seams may cause a twist displacement of needle thread. Through careful fixation and stretching and through their well-balanced elasticity the continu-ousfilamentsSerafilandONYXareoptimallypreparedtomasterthese demanding sewing operations.

Because of their improved thread locking, corespuns SabaC and Rasant aremore compact and therefore superior to continuous filaments in these applications.

Boot lining seamsThe standard overedgestitch or flatlock seams used in sewing boot linings produce on all materials a flat seam that won’t pinch the foot.

SabaC80orRasant75producesoftseams.Further,duetotheirtextilesurface, both seams provide for a reliable stitch forming process and therefore durable connections.

Automated lockstitch machines

In the leather processing industry, programmable multidirectional automated lockstitch machines have become a standard. By the different seam directions the multidirectional feed yields unfavo-rable thread flow at the needle. By this thread displacements and uneven seam appearance are caused. Because of Serafil's and ONYX'sgreatthreadlock,thesewingbehaviourandthustheseampattern are optimal too. These automated sewing machines' require-ments are therefore fulfilled. Due to this special threads, such as bonded sewing threads, are not necessary and often have other disadvantages.

Lockstitchwithgoodthreaddistribution(closingseams)

Lockstitch with a thread distribution typical for decorative seams on leather

Bootliningseam(flatlock)

Relationofseamelasticitytostitchdensity

3 4 5 6 7

Seam

ela

stic

ity

Stitches/cm seam length

50

40

30

20

10

0

7

Practical tests have shown that skilfully programmed stitching direc-tions can prevent less attractive seam appearance. In case of parallel seams it should be checked whether it was not better to lose some time for running back and thus achieve a significantly improved seam pattern.Ofspecialimportanceforprogrammableautomatedlock-stitch machines is that the best suited needle point and needle size is used and correctly positioned. Depending on their cutting profile, cutting needles produce a typical seam pattern in the sewing direc-tion; this makes a change in sewing direction visible. To avoid this, we recommend using SD1 or SD points which have a cutting feature but do not show the cutting direction.

If these conditions are fulfilled, the successful use of automated lock-stitch machines is guaranteed.

NeedlesWhenprocessingleatherandsimilarmaterials,sewingmachinenee-dles are of special importance. The needle must be carefully selected because all types of leather and artificial leather need to be sewn with cutting point needles. The relevant cutting profiles and needle sizes in combination with sewing thread and stitch density determine thelookofaseam–industrymodeldesignersshouldconsidertheneedle point form of the different seams already during the design phase.

In general, leather and imitation leather resist penetration more than a woven or knitted fabric. Since sewing machine needles with cutting points penetrate leather easier than the ones known as displace-ment points, they are primarily used for leather and artificial leather. During penetration, it cuts the leather so that the needle needs less energy for material displacement; as a result the needle is not heated as much. This allows the use of finer needles. Combinations of leather, wovenorknittedfabricshouldbesewnwitharegularroundpoint"R"in order to prevent damage to warp and weft threads or loops.

The needle sizes for different sewing operations depend on vari-ous factors:

• Howthickorhardaretheshaftorliningmaterials• Howaretheseamspositionedintheshaft• Crossseams• Theintendedmachinetype,etc.

Quilting pattern

© Groz-Beckert KG

Service & Technology8

The following recommendations for needle sizes can be used as guidelines

In all lockstitch machines where the vertical hook is positioned at the left of the needle, twist displacement occurs with Z-twisted threads which easily leads to thread break. In this position, nee-dleswitharight-twistedpointgroove(CRneedles)haveprovensuccessful. However, in two-needle machines it is not necessary tousealeft-twistedpointgrove(CLneedle)ontherightbecausethe conditions here are normal and regular needles without point grooves produce fully satisfactory results. This helps reduce the number of needles to be kept in storage and eliminates the likeli-hood of confusion.

The effectiveness of the twisted point groove is based on the fact that the thread is not pulled over the edge of the eye but safely passes through the groove. The picture above shows the form of the eye area, with and without thread. For comparison, see the following pictures of standard needles.

Needlewithright-twistedpointgroove,CR

Needle with regular eye

Needle size recommendations for sewing with Serafil

Serafil 10 Nm 160-200

Serafil 15 Nm 130-160

Serafil 20 Nm 120-140

Serafil 30 Nm 110-130

Serafil 40 Nm 90-120

Serafil 60 Nm 80-100

Serafil 80 Nm 70-90

Needle size recommendations for sewing with Rasant

Rasant 11 Nm 160-180

Rasant 15 Nm 140-160

Rasant 20 Nm 130-150

Rasant 25 Nm 130-150

Rasant 35 Nm 110-130

Rasant 50 Nm 100-110

Rasant 75 Nm 90-100

Needle size recommendations for sewing with ONYX

ONYX 10 Nm 160-190

ONYX 13 Nm 160-190

ONYX 20 Nm 140-160

ONYX 30 Nm 120-140

ONYX 40 Nm 100-120

ONYX 60 Nm 90-100

ONYX 60/2 Nm 90-100

ONYX 80 Nm 80-100

Needle size recommendations for sewing with SabaC

SabaC 25 Nm 130-160

SabaC 35 Nm 110-130

SabaC 50 Nm 100-110

SabaC 80 Nm 90-100

Needle size recommendations for sewing with Serabraid

Serabraid 800 Nm 180

Serabraid 1000 Nm 200

Serabraid 1200 Nm 230

Serabraid 1400 Nm 250

Needle size recommendations for sewing with I-tech

I-tech 20 Nm 120-160

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Because this special needle is produced in few needle systems only, we recommend using the SAN® 5 needle from Groz- Beckert as an alternative. The Groz-Beckert SAN® 5 needle features a deep hollow profile and a special eye form with an extended eye groove edge, which protects the sewing thread even better and reduces twist displacement.

Water and seamsWatertightrequirementsforupperscanbefulfilledthroughleatherimpregnation. More difficult however is the sealing of the seams because the sewing thread alone is not able to fully fill the stitching holes.

And one must differentiate between water-repellent and watertight seams.

Water-repellent seams

This is to hinder and delay the penetration of water through the stitching holes.

It is achieved through hydrophobising; the sewing thread receives awater-repellentapplication(WRfinish).Thismeasurehindersthetransport of humidity along the thread surface of synthetic sewing threads, which is called capillarity. Further, the hydrophobising proc-esssuppressesthewickingoftheabsorbentcottoncoverofRasant.

Watertight seams

Watertightseamscanonlybeachievedifthestitchingholesarefilled with an elastic permanent sealer. The easiest way is to apply itbyhand.Reliableresultsareachievedifaseamsealingpressisused which presses the sealer through the stitching holes from the inside. However this must be done carefully since there is a risk of spots on delicate colours. Another option is to cover the seams on the inside with suitable sealing strips by glueing or bonding.

Both methods however require the use of the finest possible needles with the appropriate form of point. These are best deter-mined by testing original materials.

Work,sportsandleisure-timeshoesareofferedwithmembranes.For this type of workmanship the membrane seams are gener-ally bonded with sealing strips. Although the inner seams are fully sealed through the bonding process, hydrophobised sewing threads are usually used as an additional safety measure. Shoe manufacturers must decide on a case-by-case basis which sealing measure they consider the most reasonable for their models.

Summary Flexing movements and tensile stress put a strain on shoe seams with every step. High quality continuous filaments such as Serafil orONYXorfirst-classqualitycorespunthreadssuchasSabaC or Rasantaretherefore inevitable inshoeproduction.Sophisticatedquality sewing threads guarantee smooth and economic production and help meet expectations in the finished product.

ThisiswhytheAMANNproductsSerafil,ONYX,SabaCandRasantare among the most widely used threads in the shoe industry.

Implications of an improperly hydrophobised sewing thread

Needle with right-twisted point groove SAN® 5 needle

© Groz-Beckert KG © Groz-Beckert KG

Service & Technology10

Polyamide continuous filament with metal component

I-tech 20 4.000 m

Overview of the AMANN article range for shoes/leather

Polyester continuous filament

Serafil 10 300 m, 1.000 m

Serafil 15 450 m

Serafil 20 600 m, 2.500 m

Serafil 30 900 m, 4.000 m

Serafil 40 1.200 m, 5.000 m

Serafil 60 1.800 m, 5.000 m

Serafil 80 2.400 m, 10.000 m

Serafil10-60isavailableinawaterrepellentqualityaswell(WR)Serafil 20-40 is available in bonded quality as well, called Serabond

Polyamide continuous filament

ONYX 10 1.500 m

ONYX 13 1.500 m

ONYX 20 2.000 m

ONYX 30 2.500 m

ONYX 40 4.000 m

ONYX 60 3.000 m, 6.000 m

ONYX 60/2 3.000 m, 6.000 m

ONYX 80 4.000 m, 8.000 m

ONYX30+40isavailableinawaterrepellentqualityaswell(WR)

Polyester/polyester corespun

Saba 81) 800 m

SabaC 25 5.000 m

SabaC 35 5.000 m

SabaC 50 500 m, 2.500 m

SabaC 80 1.000 m, 5.000 m1) Cut staple

Polyester/cotton corespun

Rasant 11 1.100 m

Rasant 15 1.400 m

Rasant 20 1.500 m

Rasant 25 2.000 m

Rasant 302) 2.500 m

Rasant 35 3.000 m

Rasant 50 1.000 m, 5.000 m

Rasant 75 1.000 m, 5.000 m

OnrequestwecansupplyRasant11-75inwaterrepellentquality(WR)aswell2) Polyamide core

Braided polyester continuous filament

T603) T90

Serabraid 800 700 m 700 m

Serabraid 1000 500 m 500 m

Serabraid 1200 500 m 500 m

Serabraid 1400 300 m 300 m

OnrequestwecansupplySerabraid1000+1400inwaterrepellentquality(WR)aswell3) Flanged cones must be positioned horizontally so that the thread can be taken off over the top.

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All facts and figures are intended exclusively for your information. All recommendations presuppose adjustment of the sewing conditions to the appropriate sewing yarn.

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TECHNOLOGYCENTRE

1000

34G

B020

0002

9

AMANN & Soehne GmbH & Co. KG

Hauptstrasse 174357 Boennigheim - GermanyPhone +49 7143 277-250Fax +49 7143 277-460

nt@amann.com · www.amann.com

Certificate No.: 09 100 6148