Chenille 3

lmportant Matters in Chenille Yarn Production

ULUDAG UNIVERSITY

Dr. Erhan Kenan even

Uludag University, Faculty of Engineering and Architecture, Textile Engineering Department

Grkle Campus,16059, Nilfer - Bursa,TURKEY

23 April 2012- TUL Dr. Erhan Kenan even 23 April 2012 2

TTURKEYURKEY


BURSABURSA


Textile EngineeringTextile EngineeringTextile EngineeringTextile Engineering DepartmentDepartmentDepartmentDepartment

UludagUludagUludagUludag UniversityUniversityUniversityUniversity, , , , BursaBursaBursaBursa , T, T, T, TURKEYURKEYURKEYURKEY

BursaBursaBursaBursa

UludaUludaUludaUluda

UniversityUniversityUniversityUniversity


OutlineOutline1. Definition and Classification of Fancy yarns2. Production Methods of Chenille Yarns3. Chenille Quality Tolerances4. Factors Influencing the Properties of Chenille Yarns5. Important Matters in Chenille Yarn Production

5.1.Electronic Clearing of Missing Pile5.2. Knots and Splices5.3. Pile Direction5.4. Abrasion Resistance

6. Modelling of Chenille Yarns for an Exemplary Practice


Fancy yarns are special products of spinning, twisting, wrapping, texturing, printing, knitting, etc. Fancy yarns are and will always be up-to-date, as there is no alternative to them.

The demand for yarns with structural and/or optical effects is due tothe special aesthetic and high decorative appeal to the woven, knitted materials, and other textiles as well. Textile materials thatare produced using yarns with effects find applications in normal and high fashion clothing. Such yarns are also used for decorativetextiles like curtains, carpets, effect wallpaper. Decor materialsand textile fabrics in the corporate sector, as for example in the trimof a car or textile furnishing of a hotel lobby are becoming more andmore important

1. Definition and Classification of Fancy yarns


The technology of differential dying of the yarns or semi-manufactured product of spinning is effective and simple in design. Colouring and decorating the product using differentialdyeing or cross dyeing techniques essentially promote the fibreproperties as design effects in themselves without any otheradditional components.


Textile designers when creating new styles and fashionabletextiles prefer differing from traditional fancy yarn structures thetape yarns or ladder-knit yarns. Such fancy yarns createextraordinary effects in the fabric made, thus augmenting theirdecorative value. Ladder-knit fancy yarn can be produced on a small-diameter circular knitting machine with three guidesfeeding each knitting head [14]. Some knitted fancy yarns haveeffect component short or long lengths of yarn, bunches of roving, etc. and colour effects as well. Examples of not traditional fancy yarns structure are presented in Fig. 2


Fancy yarns have deliberately introduced irregular characteristics, in either diameter and bulk and/or in color, etc. as well as virtually newstructures composed of fibers, yarns or other products that differentiatethem from conventionally spun or multifilament yarns [1 3]. New looks, structures and raw materials of fancy yarns are constantly in demand.


Components of fancy yarns can be of natural or man made fibers: staple length or continuous filaments but nowadays it appears theespecially unusual structures of fancy yarns that are very desirable in designing of new textiles. There are so many different types of fancyyarns. Most of them are produced using spinning or twisting machinerythat are modified or specially developed for this purpose.

Some types of such yarns are produced from fancy fiber or fancyslivers used as minor components of yarns made by spinners withnormal equipment, still others are made exclusively by filament yarnsusing adaptations of various processes as well as tape-knit fancy yarnsare produced using a range of take-up rations and component yarns on a knitting machine specially designed for fancy yarn manufacture.


In [3] the assortment of fancy yarns is grouped into two groups: withoverfeed and controlled effects. Each of these two groups has two subgroups: yarn effects andspinning effects.

For example, the overfeed yarn effects are loop, onde, snarls, wildknop, wild caterpillar, etc. The controlled yarn effects are knop, caterpillar, reverse caterpillar, and combined effects. Overfeedspinning effects are onde, spun loop, chenille, boucle, etc.

Unfortunately, such a method of grouping is restricted and not precise because not all types of the assortment are included. Besides that, there are no motives of ascription and substantiation.


Chenille is a pile yarn that has been produced commercially since the 1970s. In 1977, the A. J. Mitchell Co. developed a machine specially designed for the manufacture of upholstery chenille yarn.

Modern machinery was introduced in Europe and North America in the early 1990s, and today's chenille is a reliable and beautiful yarn that is gaining in popularity.

2. Production Methods of Chenille Yarns


Figure 6 shows the basic structure of a chenille yarn. It consists of a cut pile (short lengths of spun yarn or filament) which may be made of a variety of fibers helically disposed around the two axial threads (highly twisted fine strong yarn) which secure it. The short lengths are called the pile and the highly twisted yarns are called the core.

Chenille yarn can be made from many different types of fibers and yarns. Most common are cotton, viscose (rayon), acrylic, and polypropylene (olefin). Chenille yarn can be made in many different sizes, ranging from as heavy as 0.2 Nm to as fine as 12.0 Nm.

Figure 6. Chenille yarn structure


Methods of producing chenille yarns

Weaving

Chenille Type

Flocking Process

Mock Chenille


Figure 7. Chenille yarn production by weaving

Weaving

leno fabric


This technique has been superseded by a variety of new systems, which create more or less convincing copies of the chenille effect. The old, leno-woven method may still be used in some, very specialist applications, but the scarcity and expense of this particular effect when this was the only method is sufficient testimony to the relative slowness (time consuming) and difficulty of the technique. It is not really a viable alternative if the goal is to create yarns for the mass market.


Figure 8. Chenille yarn production: a: Yarn forming zone showing depth of the former; b: Yarn forming zone

a b

Chenille Type


Figure 9. Chenille Machine


Like velvet and other pile fabrics, the chenille yarn made using this process has what is in effect a nap illustrated in Figure 10. This is caused by the interlacing of the pile and the core, and it means that in later treatment of the yarn, the number of winding processes needs to be carefully monitored, in order to ensure that the nap lies in the same direction on all cones or cheeses in a batch. If this is not done, the fabric in which the yarn is used will show color differences resulting from the differing reflectance of the nap, which depend upon the angle of the pile and of the light.

Figure 10. Chenille structure showing nap


Flocking Process

Figure 11. The flocking process


A mock chenille effect can be produced by plying two gimp or bouclor loop yarns with dense effects, for example, two loop yarns with large numbers of small loops. The yarn may not look like chenille, but when the yarn is then made in to fabric, the large number of small loops in the fabric results in a fabric surface that resembles a chenille effect.

Mock Chenille


Table 1: International Specification for Chenille Count and Twist Tolerances

2.04.06.010.020.0Twist (% )

2.04.06.010.020.0Count/Yield (% )

100251051Sample Size

3. Chenille Quality Tolerances


Core and effect yarn material Yarn count of the core and pile yarn Pile length, mm (determined by the size of the caliper) Yarn twist, turns/meter (determined by the spindle speed and thedelivery speed) Retraction value ,% (the length of yarn is reduced because of twisting core yarns) Rotary head speed, rpm (determines pile density) Rotary head diameter, mm Spindle speed, rpm (determines twist level) Winding speed, m/min (determines production speed) Pile density (determined by the speed of the head)

4. Factors Influencing the Properties of Chenille Yarns


5. Important Matters in Chenille Yarn Production

Electronic Clearing of Missing Pile

Chenille is manufactured in a two step process.

Step one is the manufacture of the chenille onto a chenille bobbin Step two is the rewinding of the chenille onto a cone or dye tube.

An electronic clearer is located in the yarn path of step two to detect lengths of yarn that have pile missing. When the electronic clearer detects a section of missing pile greater than the minimum setting specified (usually 3 mm), a cutter is electronically activated. The yarn is cut, and the winder operator then pulls the yarn back and cuts out the missing pile section, reties the yarn, and continues winding the package. The electronic clearer devices are almost 100% effective.


Knots and Splices

There are two alternative methods for "tying" the chenille yarn.

Method one is a core knot. This is made by stripping back the pile of both ends of the chenille sufficiently so that it is possible to tie a double square knot in the core yarns. Care has to be taken to hold the twist in the yarn ends where the pile starts. Once the double square knot is tied, the ends are clipped close to the small knot. The pile ends are then pushed over the knot.

Method two uses a splice. To create the splice, the two ends of chenille are overlapped 1 to 2 inches and a mechanical wrap-around splicing device applies the wrap yarn. The wrap yarn can be either a fine monofilament nylon or a very fine yarn of the same fiber as the chenille pile.


Pile Direction

The chenille manufacturing process creates pile that lies in onedirection. When woven into a fabric, chenille reflects light differently when viewed from different directions. This is known as the "reflection effect," and it is one of the unique and desirable characteristics of chenille goods.

Following step one of manufacturing, the yarn has direction one.After the winding process in step two, the yarn has direction two.

Because of this, strict control of the pile direction must be maintained during both the step of manufacturing the chenille and also all subsequent processes required to convert the chenille into a finished article. It is not possible accurately to visually evaluate the direction of natural or dyed chenille yarn in its yarn form.Weaving the chenille yarn into a solid test fabric is the only way of detecting the true direction of a yarn.


Abrasion Resistance

Any removal of the effect yarn forming the beard, either during further processing or during the eventual end-use, will expose the ground yarns, which will in turn result in this bare appearance. To avoid this undesirable result, several options are available, or a combination of them may be chosen.

These include: Creating a longer pile in chenille yarn will offer greater resistance to being pulled out and will also take longer to abrade The use of longer fibers in the effect yarn The use of higher twist level in the creation of the chenille itself, in order to offer greater resistance to the removal of the effect yarn Careful choice of pile and core yarns to increase the inter-fiber friction may also assist in reducing the pile loss rate The use of natural fibers in the production like cotton will help to produce yarns having high abrasion resistance


These important characteristics are also enhanced by the addition of a thermoplastic filament to the composition which has significantly reduced the main problem of shedding to which early chenille yarns were prone. The application of heat at the appropriate point in the process, before the yarn is wound onto a package enables the yarn to be set.

The use of the thermoplastic fiber brings its own challenges in production, especially since the relatively low melting point may result in the activation of the filament at the wrong time; the thermoplastic filament may melt completely and run down the "beard", settling in beads on the ends of the fibers.


Developments of the method of construction have largely eliminated these problems; low melt fibers have been inserted in the core which fuses with the pile under subsequent heat processes to help increase pile adhesion and clever methods of pile yarn insertion have created a more rounded yarn effect yet still retained the somewhat unique character of the chenille.

Pile loss is encouraged by inadequate fiber adherence. Careful choice of the pile and core yarns to increase the inter-fiber friction may assist in reducing the rate of loss of the pile. Nevertheless, creating a longer pile, using higher twist levels and the use of natural fibers in the production will help to produce yarns having high abrasion resistance.


6. Modelling of Chenille Yarnsand

Deriving a Formula for Yarn Count Estimation


Description of Basic ParametersDenotation UnitNmch: Chenille yarn count meter/gramNmc : Core yarn count meter/gramNmp : Pile yarn count meter/gramnrh : Rotary head speed rev/minutens : Spindle speed rev/minuteL : Production speed meter/minuteT : Chenille yarn twist level turns/meterR : Retraction value in percent %Lzt : Length of zero twist yarn meterLt : Length of twisted yarn meterk : Circumference of the caliper metercw : Caliper width meterct : Caliper thickness meterckt : Cutting knife thickness metera : Pile density rotation/meterh : Number of pile yarns fed into the rotary headz : Number of pile yarns per one twist of the chenille yarnWc : Core yarn weight for 1 meter of chenille yarn gram/meterWp : Pile yarn weight for 1 meter of chenille yarn gram/meterWch : Chenille yarn weight for 1 meter of chenille yarn gram/meterLp : Pile yarn length for one meter of chenille yarn meterLpt : Pile yarn length for 1/T meter of chenille yarn meter


Relation between the Basic Parameters

We determined the actual length of the core and pile yarns in 1 meter of chenille yarn and then determined the weight of the component yarns.

Wc = (1)

We took into account the retraction of the yarn due to the twist.

R = (2)

Pile yarn weight for 1 meter of chenille yarn:

Wp = (3)

+

10012 R

Nmc

100t

tzt

LLL

p

rh

NmLknh

2


In this equation (3):

Circumference of the caliperk = (4)

Production speed

L = (5)

Pile density

a = (6)

( ) ( ) ( )( )ttw ckcc ++ 242

Tns

Tn

n

Ln

s

rhrh =


Chenille yarn weight is the sum of the core yarn weight and pile yarn weight. Hence from (1) and (3) we get:

(7)

(8)

From our measurements and computation, we denote the following expression, Nmch, for determining the final count of the chenille yarns.

(9)

pcch WWW +=

=chW

+

+

p

rh

c NmLknhR

Nm 210012

=chNm ( )( )( ) ( )

++

cp

pc

NmkhaNmRNmNm

5.0100/12


According to equation 9, we can draw the following:

Increasing nrh and decreasing L lead to increased a, resulting in the production of coarser yarns.Decreasing L at constant ns leads to increased T and R; these lead to the production of coarser yarns.


Also we found a formula for calculating the number of pile yarns per one twist of the chenille yarn (z):

If the twist level is T for chenille yarn, the length of one twist is 1/ T meter.Also we considered the number of pile yarns fed to the rotary head.

Pile yarn length for 1 meter of chenille yarn:

Lp = (10)

Pile yarn lengths for 1/T meter of chenille yarn:

Lpt = = (11)

Number of pile yarns per one twist of the chenille yarn (z):

z = (12)

.

hk

Lnrh

2

TLp

TLhknrh

2

TLhnrh


From (5) and (12) we get: z = (13)

The z parameter in equation 13 can be used for the prediction of yarn appearance before the production of chenille yarns. The border value of z can be used as a reference for the yarns which must have enough pile density.

s

rh

n

nh


Table 2. Range of the values belong to chenille yarn parameters

0.4-0.6Caliper thickness, mm0.7-3.0Caliper size, mm

0.20-1.00Rotary blade

0.15-0.20Gillette typeKnifethickness,

mm

700-1200Yarn twist, turns/meter1-3Number of the pile yarns

20-50Core and pile yarn count, Nm1-12Chenille yarn count, Nm4-24Production speed, m/min

3700-8500Spindle speed, rpm7500-24000Rotary head speed, rpm

RangeParameters


There is a good correlation with high value of correlation coeffThere is a good correlation with high value of correlation coefficient icient (above 0.95)(above 0.95) between the measured and calculated counts of the between the measured and calculated counts of the chenille fancy yarns. chenille fancy yarns.

This result seems to be promising for assessing the count of This result seems to be promising for assessing the count of chenille fancy yarns. chenille fancy yarns. It will be a practical method and enable a rapid It will be a practical method and enable a rapid interpretation.interpretation.


Figure 13. Calculated and measured chenille yarn count values versus yarn number


Figure 14. Calculated and measured chenille yarn count values versus yarn number


Figure 15, 16, 17 and 18 illustrates the changes for chenille yarn counts versus pile yarn counts for selected constant yarn and machine parameters and variables according to expression 9.

These figures help for observing the effects of the changes on chenille yarn counts for some variables like pile length, production speed, rotary head speed and core yarn count.

Graphs and equation 9 can be used for both reproducing an existing chenille yarn and creating a new type that has been merely designed on a paper.


Figure 15. Chenille yarn counts versus pile yarn counts for different pile lengths (caliper widths)(Constant values: nrh =16860 rpm, ns =5130 rpm, L, = 7.12 m/min, Core yarn count = Nm 33.86, h = 1,R = 5 %)

Caliper width


Figure 16. Chenille yarn counts versus pile yarn counts for different production speeds(Constant values: nrh =16860 rpm, Core yarn count = Nm 33.86, h = 1, R = 5 %, Caliper width = 0.7 x 10-3 m,

k= 4.4 x 10-3 m)

Production speed


Figure 17. Chenille yarn counts versus pile yarn counts for different rotary heads speeds(Constant values: L = 7.12 m/min, Core yarn count = 33.86 Nm, h = 1, R = 5 %, Caliper width = 0.7 x 10-3 m,

k= 4.4 x 10-3 m)

Rotary head speed


Figure 18. Chenille yarn counts versus pile yarn counts for different core yarn counts.(Constant values: nrh =16860 rpm, L = 7.12 m/min, a =2367.98, h = 1, R= 5 %, Caliper width= 0.7 x 10-3 m,

k= 4.4 x 10-3 m)

Core yarn count


Conclusion There are two main features of chenille production techniques which cause problems for use; one is pile direction and the other is the tendency for the pile yarns to pull out of the core during end use.

While producing chenille yarns in chenille machines, piles lie in onedirection. The chenille yarn user must take care to maintain the same pile direction throughout manufacturing.

An expression is derived to determine the final count of chenilleyarns. Correlation analysis confirmed strong linear relationship with high value of correlation coefficient (above 0.95) between the final count values of chenille yarn samples obtained from the expression (formula) and that obtained from the measurements.

Chenille 3

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