Yarn Hairiness

Yarn Hairiness 2013

By Mr. Sunil Kumar Sharma, Dy. General Manager – QA, PPC & Customer Care, Published in Spinning Textiles, Vol.7, Issue-6, Nov. Dec.2013 Edition.

Question – 1 : - What is yarn Hairiness and how it is impact on spinning,

knitting & weaving processes & yarn, fabric Quality ?

Ans. : Hairiness is characterized by the quantity of freely moving fibre ends or fibre

loops projecting from a yarn or textile fabric (woven, knitted or non woven fabrics).

In term of measurement Hairiness corresponds to the total length of the

protruding fibres in unit length of one centimeter.

Yarn hairiness is a complex concept, which generally cannot be completely

defined by a single figure. The effect of yarn hairiness on the textile operations

following spinning, knitting & weaving and it’s influence on the characteristics of

the product obtained may be as follows : -

1. High fluff – fly generation in ring frame, winding & subsequent processes.

2. Excessive yarn breaks at ring frame stage.

3. Higher yarn breaks at knitting or warp creel.

4. Pipe choking of Circular Knitting machine causing frequent yarn breaks

and hole in fabric.

5. Barre or Shade variation in fabric.

6. High pilling in knitted fabric.

7. Linting problem in terry towel.

Question – 2 : - What are the commonly used test methods for Hairiness

testing? Explain their measuring principles?

Ans. : There are two popular methods for yarn hairiness testing as below : -

1. Hairiness Index tested through OH sensor with Evenness Tester.

2. The Number of hairs in several length zone counted.

Hairiness Index tested through OH sensor with Evenness Tester : - A

constant monochrome light source shines on the protruding hairs of the yarn

body, which scatters the parallel light. The yarn body itself is dark, because it

is not transparent. The scattered light, which is caused by those fibres

protruding outside the yarn body, is bundled by a lens system and detected by

Yarn Hairiness 2013


an optical sensor. The scattered light results from the refraction, diffraction

and reflection at the individual fibres i.e. the protruding fibres appear to be

luminous. The electrical output signal of the optical sensor, which is

proportional to the yarn hairiness, is then converted to a digital value and

evaluated by the tester.

Total length of Protruding fibres (in cm)

Hairiness Index = --------------------------------------------------------

Total length of yarn tested (in cm) Fig. 1 : Representation of Hairiness

The Number of hairs in several length zone counted : - The measuring

method used is based on the photometric principle. The yarn and projecting

fibres interrupt a light beam, thus effecting a fluctuation in the measuring

luminance of the light beam. The luminance registered in this way by a

phototransistor is converted into a photocurrent, which must be amplified. In

Yarn Hairiness 2013


order to allow the number of hairs in several length zones to be counted, the yarn

is scanned by four photo-transistors. The measured values were entered into a

logarithmic coordinate frame. Fig. 2 : Representation of Hairiness in the Coordinate Frame

Question – 3 : - What is S3 value? What is the basic difference between two

testing methods of Hairiness testing and what is the use of both the methods?

Ans. : As mentioned above type 2 instruments provide the information that how

much number of fibres belong to a particular length. In this method total number of

hairs 3.0 mm and longer is known as S3 Value

For a textile yarn long hairs are undesirable, while short hairs are desirable for soft

feel of fabric. Hairiness value obtained through OH sensor of evenness tester is the

average of all protruding fibre length in one centimeter length of yarn, which is not

indicating the distribution of the length of hairs. Let us see an example as below : -

Two yarns samples tested on evenness tester, where Hairiness Index of both

the yarn obtained same as 5.0, while same yarn samples again tested on another

tester which gives detail analysis report for individual length of hairs shows that S3

value of sample 1 is more as compared to sample 2, which indicates that yarn

sample 1 is more hairy as compared to sample 2. Hence Hairiness index obtained

Yarn Hairiness 2013


from evenness tester is just indicative value, which is indicating the trend of

spinning process while second method is require for detail analysis of yarn hairiness

and may help to identify and eliminate the root cause.

Question – 4 : - What are the influencing factors for yarn Hairiness?

Ans. : Hairiness occurs because some fibre ends protrude from the yarn body,

some looped fibres arch out from the yarn core and some wild fibres in the yarn.

Following are the major influencing factors affecting the yarn hairiness : -

Raw Material Quality.

Production rate or processing speeds.

Process parameters.

Mechanical conditions of machines.

1. Raw Material Quality (Cotton) : - Raw material quality is most important

influencing factor for yarn hairiness. Fibre length, Fineness, Short fibre %,

Uniformity, maturity and strength each parameter impact their influence on yarn

hairiness as below : -

a. Fibre Length : - Cotton selected of lower fibre length will causes high yarn

hairiness, also lead high fluff generation and more tendency of traveller

loading which further increasing hairiness. The greater length corresponds

to less hairiness. Ref. Chart – 1.

b. Fineness : - The number of fibres in yarn cross section also affect the yarn

hairiness. The proportion of fibre ends that protrude from the yarn surface,

counted microscopically has been found to be about 31 % of the actual

number of ends present in the yarn, hence as number of fibres increases

there will be higher possibilities for increase in yarn hairiness.

c. Short Fibre % & Uniformity : - Higher the short fibre % lower will be

uniformity of cotton which ultimately lead high hairiness in yarn.

Yarn Hairiness 2013


d. Maturity & Strength : - Lower cotton maturity & fibre strength causes fibre

rupture in process and increases the short fibre % ultimate causes high yarn

hairiness. Chart – 1 : Hairiness Index w.r.t. cotton parameters

(For 30s Combed Hosiery Yarn)

Description Test -1 Test -2 Test -3 Test -4

Fibre Length (mm) 28.3 29.5 29.8 30.2

Uniformity Ratio % 47.8 48.3 48.5 48.7

Micronaire 3.78 4.28 4.02 4.10

Strength (Gms/Tex) 21.1 21.4 21.6 22.0

Short Fibre % 10.9 9.9 9.3 8.8

Hairiness Index 7.10 6.80 6.56 6.40

2. Production rate or processing speeds : - Yarn hairiness significantly increases

with increase in spinning machine speeds or production rate. The effect of

spinning machines speeds on yarn hairiness varies according to their sequence in

spinning process, however impact of each spinning process on yarn hairiness is

given on chart -2 for reference : - Chart – 2 : Impact of increasing speeds on Yarn Hairiness

Process Impact on Yarn Hairiness by increasing Speed.

Carding Moderate Br. Draw Frame & Lap former No effect Comber & Fin. Draw Frame Moderate Speed Frame Slightly increases. Ring Frame & Autoconer Greatly

Hence it is advisable to optimize the spinning process speeds according to

Quality requirement.

Yarn Hairiness 2013


3. Process Parameter : - Spinning process parameters are major contributing

factor for yarn hairiness. Following are the major contributing process

parameters for yarn hairiness : -

a. Narrow Guides : - Sliver Guides, trumpets & sliver tubes at DF’s,

combers and lap former to be selected narrow as possible to condense the

sliver fleece and roving. This helps to reduce the yarn hairiness.

b. Adequate draft at BDF to Lap former : - In modern spinning set up total

drafts in Br. DF to Lap former is recommended as 7.0 to 9.0. Total draft

more than this limit may lead increase in yarn hairiness.

c. Lap batt weight : - Significantly higher lap batt weight at comber also lead

high hairiness in yarn.

d. Greater parallelization : - Better parallelization in preparatory process

helps to reduce yarn hairiness.

e. Linear density of roving : - Yarn hairiness increases when the linear

density increases. This is due to the increases number of fibres in the web

and due to higher draft requires to spin the yarn.

f. Twist at roving & yarn : - Higher the twist at roving and ring frame

results into low hairiness.

Ring frame process parameters influencing yarn hairiness : - As ring

frame is the ultimate place for yarn production, hence each process parameter

of ring frame influence on yarn hairiness, these are as below : -

i. Spinning Geometry : - Construction of spinning machine can

significantly influence the yarn hairiness, the arrangement of the drafting

elements and size of spinning triangle are the greatest important.

ii. Size of Spacer : - Selection of spacer size also significantly impact on

yarn hairiness. A wider size spacer to be selected for reducing the yarn

hairiness, however it might increase the yarn imperfection.

iii. Selection of Ring & Ring Diameter : The right selection of type of

ring, quality of rings are the greatest important for yarn hairiness.

Yarn Hairiness 2013


Following points to be taken care while selecting the ring & ring

diameter w.r.t. yarn Hairiness : -

2 Flange ring may consider for coarse count range i.e. below 24sNE for

lesser yarn hairiness.

The ring diameter can be chosen 25 mm smaller at a maximum with

regard to the spindle gauge.

The ring diameter should be in between 1.8 to 2.1 times of top of

spinning tubes.

The ring diameter should be maximum 1/5th of the spinning tube length.

Ring diameter should be 2 – 3 mm less as compared to balloon control

ring.

Ring condition & ring life is major influencing factor for yarn hairiness.

1. Right choice of Ring traveller : - Right selection of ring traveller make,

traveller number or weight, traveller profile and traveller life are very

important factor for yarn hairiness. User may select right profile, make and

traveller number by conducting several trails w.r.t. yarn hairiness and breaks

level. Widen bow height and slightly heavier ring traveller helps to reduce the

yarn hairiness. The spinning tension has a considerable influence on the yarn

hairiness, the smaller the tension the greater the hairiness, thus heavier ring

traveller results in low yarn hairiness. However if traveller is too heavy yarn

hairiness will also increase, hence adequate ring traveller weight is must

require to get minimum yarn hairiness.

iv. Thread Guide setting : - Distance of the thread guide from the top of

the tube should be 1.5 to 2.0 times of ring diameter. Bore diameter of

thread guide also impact on yarn hairiness, smaller bore size reduces

yarn hairiness.

v. Anti-ballooning ring : -Size of the anti-ballooning ring should be ring

dia + 2.0 mm and distance from ring rail to anti ballooning (ring rail in

Yarn Hairiness 2013


starting position) should be 2/3 of the distance between ring rail to

thread guide.

vi. Traveller Cleaner setting must be applied according to ring traveller

size & count pattern.

vii. Ring Rail Lift : Hairiness changes greatly with increasing in ring rail

lift especially at the top of the bobbin.

viii. Yarn hairiness increases with bobbin tip to bobbin base by almost 25 %

due to change in degree of ballooning, yarn tension, position of ring rail,

yarn angle at ring traveller and the condition of the ring traveller.

ix. Atmospheric condition : - Yarn spun in dry atmosphere observed more

hairy hence an ambient environment to be maintained in spinning

section.

Winding process parameters influencing yarn hairiness : It has been

observed that yarn hairiness increases at modern high speed winding machine

by 20 to 30 % and it is also too much varying according to different winding

process parameters, these are as below : -

i. Higher the drum speed higher will be yarn hairiness.

ii. Higher the winding yarn tension high will be yarn hairiness.

iii. High cradle pressure also lead high yarn hairiness.

iv. Metallic yarn guides in yarn path increases yarn hairiness hence it is

advisable to replace all metallic yarn guides with ceramic yarn guides.

v. Winding atmospheric condition also impact on yarn hairiness hence

relative humidity in winding section should be kept in the range of 55 -

65 %.

4. Mechanical conditions of machines : - Poor mechanical condition of ring

frame & winding section lead sever problem of high yarn hairiness such as

eccentricity of spindles, deform spinning tubes, out ring setting, worn out rings

& ring travellers, scratched & off alignment ABC ring and thread guides,

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damaged roving guides etc. Hence all these things to be require proper care at the

time of preventive maintenance of ring frame.

Similarly in winding section all tension devices, thread guides, drums &

suction arms require proper care and defective parts should be replaced on

priority. These abnormalities create sever hairiness variation in yarn which may

also lead shade variation or barre problem after fabric dyeing.

Conclusion : - Hairiness is characterized by the quantity of freely moving fibre

ends or fibre loops projecting from a yarn. Yarn hairiness significantly influence

the characteristics of yarn & fabric appearance and working performance of

spinning to it’s downstream processes. There are two commonly used test

methods available for yarn hairiness testing. Hairiness index obtained from

evenness tester provides the hairiness index i.e. the total length of protruding

fibres in unit length of yarn while another method provides detail length

distribution of hairs. For a textile yarn long hairs are undesirable while short

hairs are desirable, hence terms “S3” value comes into the force which denote to

the total number of protruding fibres having length 3 mm and longer. There are

four major influencing factors for yarn hairiness which has been explained in

detail. These are as : -

Raw Material Quality.

Production rate or processing speeds.

Process parameters.

Mechanical conditions of machines.

By effective monitoring of these factors yarn hairiness may be improved

significantly and maintain at comfortable level.

Produced by : Mr. Sunil Kumar Sharma,

Dy. General Manager – QAD, PPC & Customer Care

Mobile No. : – 09552596742, 09921417107

Yarn Hairiness 2013


E_mail : - [email protected] Loknayak Jayprakash Narayan Shetkari Sahakari Soot Girni Ltd.

Kamalnagar, Untawad – Hol, Shahada,

Tal. : - Shahada, Dist. : - Nandurbar (MS)

Pin : - 425409

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