POSITIVE YARN FEEDINGPOSITIVE YARN FEEDING

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How it affects to the fabric qualityHow it affects to the fabric quality

GROUP MEMBERSGROUP MEMBERS

Narampanawa R. D. BNishshanka N. A. K. P. NPahathkumbura D. K. BRanasinghe D. D

YARN FEEDING SYSTEMSYARN FEEDING SYSTEMS

POSITIVE YARN FEEDINGNEGATIVE YARN FEEDING

The needle draws yarns directly from the package (Beam, Cone etc…)

An external element decides the yarn length released to the needle

DRAW BACKS OF NEGATIVE YARN FEEDINGDRAW BACKS OF NEGATIVE YARN FEEDING

Feed rate (amount of yarn) and Yarn tension will be vary from yarn to yarn

Decrease the fabric quality.

Yarn breakages

Reduction in production efficiency.

POSITIVE YARN FEEDINGPOSITIVE YARN FEEDING

Avoid drawbacks as non uniform Feed rates

and Yarn tension variations

How?

The positive feed units usually driven by

external force (motor, gear driven) rather than

by the needles, extract yarns from the

packages and deliver them to the needles.

POSITIVE YARN FEEDING SYSTEMPOSITIVE YARN FEEDING SYSTEM

Yarn storage feeder

Positive storage yarn delivery device

Tape feed mechanism

Each yarn from the package is passed in between

its own Feed Wheel and the Drive Tape

TAPE FEED SYSTEMTAPE FEED SYSTEM

This is commonly used in circular knitting machines.

By changing the Quality Adjusting Pulley diameter, yarn delivery speed can be alter.

Continued……..Continued……..

DrawbacksDrawbacks

Due to slippage of the yarn in between drive tape and the feed tape, yarn feed rate can be affected.

Deformed loops will be formed from this knitting system.

Quality Wheel can not be adjusted while machine been operated

Yarn faults cannot be detected before the knitting zone.

Yarn Storage FeederYarn Storage Feeder

This system is used when the structure differs

from knitting system to knitting system and from

course to course within the pattern (ex : multi

color jacquard)

DrawbacksDrawbacks

Does not feed the yarn to the needle as a fully positively feeding system. (only up to the temporary storage)

Positive storage yarn delivery devicePositive storage yarn delivery device

This is a combination of tape feeder and the yarn storage.

Positive storage yarn delivery device…Positive storage yarn delivery device…

Positive storage yarn delivery device…Positive storage yarn delivery device…

Detect yarn faults before entering to the knitting zone.

Increase the efficiencyReduce needle breakages

Fabric quality through positive yarn feedingFabric quality through positive yarn feeding

Provide the foundation for the plating technique.

Controls the fabric properties ( gsm, composition, performance such as stretch ability)

Faults of yarn are detected prior to knitting zone which reduce defects of the fabric.

Uniform stitches give better fabric appearance.

FunctionFunction

Winding reelThere different winding reelsClosed wheel – prevents filament buildingThread wheel - in case of irregular thread consumption

Anti-filamentation unitIn filament yarns capillary filaments can collect onthe winding reel. This is prevented by selecting the correct take off position.

Feed rate tape selector

Vibrating yarn tensionerprevents the build up of dirtbetween the tension rings and prevent false stoppage.A magnetic tension ring applies a uniform tensioning force .

FunctionFunctionFeed Rate Tape Selector – gives the correct amount of for each course.Ex : Half Milano

In here yarn is constantly fed in the positive feed Mode.

Friction Drive Mode - On machines with variable yarn consumption (e.g. drop stitch pattern or mini Jacquard machines), this should be run in the friction mode.

But this still can not be used for complex structures where the yarn consumption differs from knitting system to knitting system.

FunctionFunction

Developments of positive yarn feedersDevelopments of positive yarn feeders

i-DSCS, Digital Stitch Control System "with Intelligence

from Shima Seiki." i-DSCS has the capability to

actively control yarn-feed in both feed and retrieval

directions as necessary. This is crucial to the precision

knitting required in WHOLEGARMENT production.

Developments of positive yarn feedersDevelopments of positive yarn feeders In seamless knitting and new warp knitting machines

have storage feeders.New storage feeders (Rojtricot) has an additional

yarn twisting and has a switch for setting the rotational direction for S or Z twist yarns.

A braking system at the end of the package body ensures that the yarn tension is uniform.

Developments of positive yarn feedersDevelopments of positive yarn feeders

►This operates continuously, without starting and

stopping. The adjustable conical magnetic tensioner

at the yarn outlet detect the tension and drive

according to it maintain constant yarn tension.

► Microprocessor is used to calculate the average

yarn usage rate and adjust the motor speed to the

yarn usage accordingly.

True Positive FeedingTrue Positive Feeding

Modern Garment shaping and Technical fabric knitting machines with patterning requires different loop lengths for different needles for each course in the fabric.

TPFTPF

This system widely uses in medical textiles such as Scan-to-knit.

Above system fulfills that requirement

How?

pre-calculate the yarn requirement and deliver the changing yarn requirement in synchrony with the feeder movement

TPF Ctd…TPF Ctd…

Course-by-course needle selection program

detailing the action of each needle across

the needle beds

Accesses this data, pre-calculates the yarn

requirement in real time as the carriage

traverses the needles and supplies the

appropriate control signals to the drive

motors

Positive Feeding on Warp KnittingPositive Feeding on Warp Knitting

Yarn beams are rotated by means of mechanical and electronic systems to give exact runner lengths uniformly.

Warp KnittingWarp Knitting

Cone and Drum mechanism is used in

mechanical systems

Electronically geared motors are used in

modern systems with the feelers.

Problem areas of positive yarn feedersProblem areas of positive yarn feeders

Yarn breakages due to friction dust, that have filaments protruding from the

yarn, that carry a relatively large amount of sizing, or that in some other way leave behind or cause traces or deposits on parts of the yarn feeder will cause an irregular feeding of the yarn and will cause a null effect on the positive yarn feeding.

With the additional force given, yarn properties be affected

Problem areas of positive yarn feedersProblem areas of positive yarn feeders

The nip roller positive feeding will require a

complex yarn path – Influences the design

of the machine

Problem areas of positive yarn feedersProblem areas of positive yarn feeders

Large fluctuations caused by individual

needle selection cannot be adopted through

positive feeding ( large area jacquards)

Due to intensive individual attention towards each and every yarn been fed

Overcoming them Overcoming them

It is the object to create a yarn feeder whose

operation properties are largely independent

of the nature of the yarn.

This object is attained by a yarn feeder having

a yarn feed wheel with a special geometry

that facilitates the feeding and payout of yarn

onto and from the yarn feed wheel.

Yarn feeder with a ceramic coated wheelYarn feeder with a ceramic coated wheel

Yarn

Ceramic coated spikes

Minimizes the effect by the heat

Friction will be at a controlled level of affection

Will make a yarn feeder, independent from the

yarn path

Change from the initial nip roller to the Change from the initial nip roller to the tape positive feeding system tape positive feeding system

CheaperAdaptableSimpler

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