Knitting technology

1. POSITIVE YARN FEEDINGPOSITIVE YARN FEEDING
&&
How it affects to the fabric qualityHow it affects to the fabric quality

2. 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

3. 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.

4. 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.

5. POSITIVE YARN FEEDING SYSTEMPOSITIVE YARN FEEDING SYSTEM
Yarn storage feeder
Positive storage yarn delivery device
Tape feed mechanism

6. Each yarn from the package is passed in between
its own Feed Wheel and the Drive Tape
TAPE FEED SYSTEMTAPE FEED SYSTEM

7. This is commonly used in circular knitting machines.
By changing the Quality Adjusting Pulley diameter,
yarn delivery speed can be alter.
Continued……..Continued……..

8. 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.

9. 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)

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

11. Positive storage yarn delivery devicePositive storage yarn delivery device
This is a combination of tape feeder and the yarn storage.

12. Positive storage yarn delivery device…Positive storage yarn delivery device…

13. Positive storage yarn delivery device…Positive storage yarn delivery device…
Detect yarn faults before entering to the
knitting zone.
Increase the efficiency
Reduce needle breakages

14. 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.

15. FunctionFunction
Winding reel
There different winding reels
Closed wheel – prevents filament building
Thread wheel - in case of irregular thread
consumption
Anti-filamentation unit
In filament yarns capillary
filaments can collect on
the winding reel. This is
prevented by selecting
the correct take off
position.
Feed rate tape
selector
Vibrating yarn tensioner
prevents the build up of dirt
between the tension rings
and prevent false stoppage.
A magnetic tension ring
applies a uniform tensioning
force .

16. FunctionFunction
Feed 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.

17. 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

18. 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.

19. 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.

20. 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.

21. 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.

22. 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

23. 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

24. 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.

25. Warp KnittingWarp Knitting
Cone and Drum mechanism is used in
mechanical systems
Electronically geared motors are used in
modern systems with the feelers.

26. 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

27. 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

28. 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

29. Overcoming themOvercoming 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.

30. Yarn feeder with a ceramic coated wheelYarn feeder with a ceramic coated wheel
Yarn
Ceramic
coated
spikes

31. 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

32. Change from the initial nip roller to theChange from the initial nip roller to the
tape positive feeding systemtape positive feeding system
 Cheaper
 Adaptable
 Simpler

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