electronic yarn clearers – a systematic approach

Electronic Yarn clearers – A systematic Approach 2012

Published in Spinning Textiles Magazine Vol 6 * Issue 7 * Sept – Oct. 2012

“Electronic Yarn Clearers” – A systematic Approach

Abstract : - The introduction of Electronic yarn clearer in mid of 19th century was

revolutionary not only for spinning mills but for it’s down & upstream too. Now a

day it is essential accessories of new generation autoconers.

In last two decay tremendous research & innovation work done in the field of

electronic yarn clearer’s that helps spinners for increasing the yarn Quality &

productivity as well as reducing rejection & waste generation with increase in

working efficiency in spinning & textile clothing industries. Many special features

have been added into these clearers for getting adequate yarn Quality and for

special Quality purposes. However it is still a hectic job for textile technicians to set

& utilize all these features at a time for improving yarn defects or improving yarn

Quality w.r.t. full customer satisfaction by achieving target productivity level.

The purpose of this article is to elaborate all these features into it’s full length

& width with respect to serve it’s purpose and suggesting how to set right electronic

yarn clearer settings with utilizing it to maximum extent by maintaining desire

Quality & Productivity level with adopting systematic approach.

Introduction : - Electronic Yarn clearers are mainly works on two different

principles as below : -

A. The Optical Measuring Principle :

B. The Capacitive Measuring Principle :

Basic mechanism of these principles given below for reference : -

A. The Optical Measuring Principle for Yarn clearing : - The optical

measuring sensing head’s works on “Infrared light transmission” principal.

The infrared light (1) is scattered by a diffuser (2) in the light field and

reaches to the photocell (3). The photocell emit’s a tension, which is

proportional to the amount of light. If a yarn (4) is brought in the light field,

parts of the light will be absorbed by the yarn. The amount of light, which hits

the photocell, is smaller. From this change, an electrical signal, the yarn signal



(5) is derived. With the optical measuring principal the yarn signal

corresponds to the diameter of the usually round yarn, which is located inside

the measuring field. Changes of the yarn diameter cause a proportional change

of the yarn signal.

Figure 1 : The Optical Measuring Principle

B. The Capacitive Measuring Principle : - In capacitive measuring principle

two parallel metal plates (i.e. electrodes) {1} works as the sensor and these

electrodes build a measuring electrical field in between the space {2} of two

electrode plates when putting on an electrical alternative voltage (3). If a yarn

(4) is brought into this field, the capacity of the measuring condenser is

changed. From this change, an electrical signal, the yarn signal (5) is derived.

The change in the capacitance depends, besides of the mass of the yarn and of

the dielectric constant of the fibre.



Figure 2 : The Capacitive Measuring Principle

C. Yarn deviation measurement : - The evaluation of yarn faults carried out in

reference to the change in signals contrast to the base yarn. No yarn in

measuring field represented by {– 100 %} signal values, when one yarn of

certain count is inserted into measuring field signals changes from {-100 %}

to {0 %} corresponds to the yarn count. Now yarn is moved into measuring

field and deviation is measured in % with respect to the base yarn value. The

changes in signal percentage refer as diameter difference. Figure 3 : The Yarn deviation Measurement

D. Coloured Foreign matter Measurement : - Colour Foreign matters are

measures against the contrast between the yarn body and foreign matter. The

intensity of the contrast does not only depend on the colour of the foreign

matters, but also on it’s base yarn surface structure. The wavelength of the

light which is used in the sensor also plays an important role. The signal

which is generated by the foreign matter is defined as the intensity of the

foreign matter. The intensity of foreign matter depends on change of the light

reflection.



E. Synthetic Foreign Matter (P) detection : - The detection of synthetic foreign

matter as polypropylene, polyamide (nylon) etc. is generally based on an

electrical phenomenon where certain materials become electrically charged

after coming into contact with another different material. The polarity and

strength of the charges produced differ according to material and surface

smoothness. That means, the further materials lie off each other in the series,

the more definitely they can be detected.

Table : 1 Electrical series of different Material

Dry Human hands, Skin Acquires a more positive charge

+

+

Leather Rabbit Fur Glass Human Hair Nylon (Polyamid) Wool Fur Lead Silk Aluminium Paper Cotton Steel -

Wood Amber Hard Rubber Nickel, Copper Brass, Silver Gold, Platinum Polyester



Saran Wrap

- Acquires a more negative charge

Polyacrylic Polyurethane Polyethane Polyethylene Polyethlene (scotch tape) Polypropylene

Classifications : - To understand the function of an electronic yarn clearers, it is

most important to know that how different defects are being classified under it.

Each electronic yarn clearers used their own terminology for different yarn defects.

For easy understanding of new generation Electronic yarn clearers broadly we can

classify yarn defects as below : -

1. Yarn Imperfections : - Unevenness of yarn is generally consider in this

class. It is further classified into following four classes that is commonly

know as NSLT classes : -

a. Neps : - Thick places less than 1 cm. length and more than 2.5 times in

diameter against base yarn are being consider as Neps.

b. Short thick : - Thick places more than 1 cm. and less than 8 cm. with a

considerable thickness i.e. above 1.5 times the base yarn diameter.

c. Long thick : - Thick places more than 8 cm. length and thickness above

1.2 times with base dia.

d. Thin places : - Thin places more than 8 cm. and diameter less than 0.8

times of base yarn.

2. Count Variation : - Deviation of count from it’s mean value which is not

allowed in finished product or it may reflect in finished fabric. This may be



further bifurcated into two classes according to it’s length & diameter

difference i.e. : -

a. Short term count variation : - Length less than 10 Mtrs.

b. Long term count variation : - Length more than 10 Mtrs.

3. Periodic defects : - Thick & thin places which always occur with the same

distance from each other, created in spinning process due to some mechanical

disturbance.

4. Splice defects : - Poor Yarn joint Quality is also create problem in next

process, either it is weak splice or bad shape splicing.

5. Foreign Matters : - Foreign matter that is different either in colour or in

properties with base yarn. Generally in textile language it is known as

“Contamination”. This is again bifurcated into two more classes i.e.

a. Contrast Foreign Matter : - Foreign matter that is different in colour

with base yarn such as dark colour fibres in grey yarn, white or other

colour fibres in dark shade yarn etc.

b. Synthetic Foreign Matter : - Foreign Matter that may be of same or

near colour of base yarn but different in properties such as

polypropylene, nylon, synthetic fibres in cotton yarn etc.

6. Winding defects : - Winding defects such as drum lapping, bunches, system

malfunctioning etc consider in this class.

7. Bad Quality / Off Standard cops : - Most of new generation electronic yarn

clearers are competent to identify the spinning bad quality cops through

different – different channels. Neppy yarn, high hairiness, excessive

imperfection & foreign matter in a single cop may be classified in this class.

Methodology for setting an Electronic yarn clearer setting : - Before proceed for

electronic clearer setting user should know about following things in detail : -

1. What is the base yarn Quality & characteristics for which user would like to

set clearer setting?



2. What is the end use?

3. What is the customer requirement?

4. Specific requirement if any?

5. What is the desire productivity level?

Who is the right person to set yarn clearers setting : A person who may reply all

above five questions are the right person to perform electronic yarn clearer settings.

In a spinning mill a Quality Assurance Manager much better understand the all

above requirements, hence a QA / QC person is only the right person for yarn

clearer setting.

How to decide yarn clearer setting : - After getting answered all above five

questions, following steps to be adopted for setting of yarn clearers : -

A. Clearing curve setting

1. Test the cop yarn classimat for atleast 500 Km. at cut mode. If classimat is

not available user can run the yarn on autoconer for atleast 1000 km. with

wide set clearing curve.

2. Now see the defects level in objectionable classes i.e. as below : -

a. Short Class : A4+B4+B3+C4+C3+C4+D4+D3+D2+D1

b. Long Class : E + F + G

c. Thin Class : H2 + I2 +I1

3. Now sum up all these defects, the sum of these objectionable defects will be

the minimum level of your NSLT clearer cuts.

4. Also sum up remaining class defects.

5. Now consider customer requirement if any, for classimat faults or fabric

defects.

6. Now prepare a clearing curve on samples clearing chart (i.e. generally

provided by suppliers) by removing all objectionable defects.

7. Apply clearing curve online and monitor it for minimum 1000 Km. length.



8. See the cuts level and again test the classimat at test mode with removing &

collecting the objectionable defects on black board.

9. Check classimat test report & defects collected on black board, if still user

found objectionable defects in yarn, then first analyze where & what type of

objectionable defects lying. Care to be taken that some defects may added

during winding process such as loose fly, wild yarn piece, Y-Yarn etc. these

defects should not be consider for setting EYC curve.

10. If classimat is not available user may use autoconer for rewinding by

applying slightly tighter setting as normal clearer curve.

11. Now further tighten the clearing curve especially where objectionable

defects lying.

12. Looking to the remaining defects, user may further fine tune the clearing

curve. If remaining faults are less and there is no possibility of significantly

increase in clearing cuts then user may further tighten the setting for better

Quality yarn.

13. Verify once again by conducting classimat or rewinding test and finalize

the setting.

B. Count channel setting : - The purpose of count channel setting is to remove

the objectionable count variation with the yarn that might be affecting the

fabric quality. User should be more alert for setting the count channel, as

acceptable count variation are very much depends on end use of yarn. The

detection of count variation is also affected by sensor used for Electronic yarn

clearer. Following guide lines may be helpful for deciding adequate count

channel setting : -

a. Capacitive measuring principle based sensors are more accurate for

count channel setting as compare to optical sensors, as capacitive

sensors measures the variation of yarn mass while optical sensors

measures change in diameter of yarn that is many times mislead by high



hairiness. Hence for deciding count channel setting user must consider

type of EYC sensor.

b. Generally count variation of +/- 3s NE from mean value does not affect

normal fabric appearance in short length.

c. User must know that Count Channel setting is not for detecting the mix

counts cops or for controlling the count CV %.

d. User may select different count setting for course & fine count detection.

Normally fine counts prominently reflect in fabric appearance, hence

selecting tighter fine count channel setting as compare to coarse count is

more beneficial for Quality angle. This must be applied if sensing head’s

are optical based.

e. User should use short length & long length count channel setting as per

variation present in their yarn. If count CV % is very high i.e. above

1.5% than use of short length count channel setting will increase clearer

cuts drastically.

f. If yarn count CV % is less than 1.5% then user must use short length

setting for removing less than 5 Mtrs. Length count variation and long

length should be selected as 20 Mtrs.

g. Care should be taken that short length count range should always kept

wider (i.e. atleast 40%) as compare to long length count range.

h. According to end use count channel setting may be apply as below : -

i. Knitting for SJ, 1x1 Rib, Woven fabric for shirting, Sheeting’s etc. : -

These qualities are most sensitive for count deviation, hence use tight

count channel setting.

ii. Knitting for Pqt, Honey Comb, 2x2 Rib, Sweaters knitting, woven

fabric for bottom weights, bed sheets, curtains etc. are less sensitive for

count variation, hence may take slightly wider setting.



iii. Yarn meant for doubling : - As yarn doubling significantly reduces the

abnormalities of single yarn, hence a wider setting may be adopted to

reduce clearer cuts.

C. Periodic defects : - Each yarn clearers have periodic defect detection facility

in their own manner. User should select this option to detect & remove the

prominent periodic defects that may damage the fabric quality. Such as Ring

frame defective front top or bottom roll is creating very sever defect in fabric.

It may be identified & removed through EYC periodic defects channel by

adopting appropriate settings. Refer following calculations for setting the

detection of defective Ring frame bottom or top roll : -

Suppose RF front bottom or top dia is = 27 mm.

Then prominent periodic faults will be repeated after distance of = πd,

Where π = 3.14 & d = diameter of front rolls are = 27 mm,

Hence, = πd = 3.14 x 27 = 84.78 mm.

Means for a RF defective front top or bottom rolls, periodic faults will be

repeated after every 84.78 mm distance.

No. of defects in one Mtr yarn will be = 1000/84.78 = 11.79 Defects/Mtrs.

Now we can set periodic defects channel as : -

Observation Length = 10 Mtrs. Or 5 Mtrs (Depend on end use sensitivity)

No of defects = 110 for 10 Mts or 55 for 5 Mtrs observation length.

Diameter & length of defects may be selected as per Quality sensitivity of

end use.

Usually diameter may be selected as 1.25 times & length 1.5 cm.

D. Splice Channel Setting : - Each yarn joint create a defects but it is a

mandatory process for spinning to joint yarn end, either it is made by cop

change or by removing yarn defect. The purpose of splice channel setting is to

detect the splice defects & remove it. Hence when a defect is replaced with a

splice one should ensure that the splice quality is better than the defect it

replaces. Week splice as thin place will create more breakages in next



processes especially in weaving process, and also create thin places & hole

formation in knitted cloth, while bad shape splices creates short thick place in

knitted & woven fabric. New generation EYC clearers have facility to detect

& remove the defective splices very precisely. Following procedure may be

helpful for set right splice channel setting : -

a. Make the black board of atleast three splices collected from each drum.

b. Identify the defective splice drums and check that in which class

defective splices are lying. It might be either checked on at autoconer

display or by conducting classimat studies.

c. Set the splice setting by removing objectionable defects and apply it.

d. Again test the yarn classimat & prepare black board and if require fine

tune it.

e. Sample reports of “Splice class settings” & “Splice clearing data” given

below in figure 4 & 5 for ready reference. Figure 4 : Splice Class Setting



Figure 5 : Splice Clearing Data

Foreign Matters : - Removal of foreign matter from cotton yarn is a difficult task for spinners especially in Indian origin cotton. As Quality consistency increasing day by day, customer quality demands put huge pressure on spinning technicians to supply contamination controlled yarn, while it is not in their hand to control the contamination level in raw material. Thanks to new generation EYC that’s helps too much to spinning technicians for fighting with this problem and now it can be controlled till an acceptable level by using foreign matter clearers. Foreign matters classified as length classes on the horizontal axis and colour contrast (i.e. darkness levels) on the vertical axis. Darkest foreign matter will be appeared on top of chart; while low contrast intensity foreign matter will comes into lower classes of chart. Figure 6 & 7 represent the classification chart for foreign matters in Loepfe Zenit & Uster Quantam clearers.



Figure 6 : Loepfe Zenit - Classification chart for Foreign Matters



Figure 7 : Uster Quantam - Classification chart for Foreign Matters

Usually setting of foreign matter clearers depends on customer requirement, however raw cotton processed through modern TMC Ginning & Pressing plants & spinning plant equipped with “Contamination sorters” have less amount of contamination. Here foreign matter of contrast more than 20 % & 2 cm. longer defects size should be avoided.

However if raw material is having high amount of contamination then tighter setting of EYC will lead excessive foreign matter cuts and ultimately drop in productivity. Therefore it is advisable to collect the foreign matter defects on a white board, select the defects to be remove, see it’s classes on autoconer display and set the setting accordingly. Similar methods may be adopted for detection & removal of synthetic foreign matters. Firgure – 8 shows the foreign matters collected from yarn on white board.



Figure 8 : Foreign Matters collected on white board.

8. Bad Quality cops / Off Standard cops : - Bad Quality / Off Standard cops

produces in spinning due to many reasons. Now it’s become very easy to

arrest them through new generation EYC’s. These settings may help a lot to

spinning technicians for identifying the defective spinning positions. These

settings may apply for defects such as neppy yarn, high hairiness, excessive

imperfection & foreign matter in a single cop. Channelization from Ring

frame to winding must require for properly utilizing these settings. Defective

spinning positions may be identified easily by running yarn on winding

machine applying these settings with proper marking on each spinning



spindle position on cops. This procedure adopted many times by the writer

for identifying the origin of defects.

9. No of Repeaters & Ejected Cops : - When repeated yarn defects occur in a

particular cop yarn, then this cop will be ejected and winding position will be

blocked. This facility provided by the Electronic yarn clearers for removing

the defective cops from the operation, but in general mills practices these

defective cops again & again feed into winding magazine and it will run

continuously till whole cop yarn sucked by the suction arm. This causes huge

efficiency losses with significantly increase in hard waste. There are also

chances of passed some defective part of yarn in finished package, which

creates problem in next processes and ultimately may lead customer

complaint and causing huge claim amount. These losses may be avoided, if it

is deal in a systematic manner. Following procedure suggested for dealing

with repeaters & ejected cops : -

Remember for each NSLT & Foreign matter cuts Approx. 3 – 5 Mtrs. Yarn

sucked from packaged, while for rest all other defects such as Count

Channel, Periodic defects, Bad Quality/Off Standard defects approx. 80

Mtrs. Yarn sucked and collected as hard waste. Hence keeping higher no.

of repeaters significantly increased hard waste, while keeping low no. of

repeaters will increase excessive cop ejections.

Hence no. of repeaters should not be kept more than three for all channels

except NSLT, where it might be kept 5.

All ejected cops should be segregated separately and should not be allowed

going with fresh material.

These ejected cops may be work with wider EYC setting for down grade

yarn purpose.

Standardization & Documentation : - After completion of all these activities a

final chart to be prepared describing all channel settings and it is to be distributed to

all concerned persons for freezing the “Standard EYC settings”. No one should



allow alerting any setting except authorized person. Whenever needs to alter the

setting, a new setting chart should be release described the alteration in highlighted

font or colour and re-circulated to all concern. Absolute copy of EYC setting &

records of various trials conducted should be preserve at-least for one year for

future reference. A standard model sheet is provided as chart -2 for reference : -



Table 2 : Model Chart for EYC setting for Loepfe Yarn Master – Zenit FC



Conclusion : - The new generation Electronic yarn clearers are more effective if it

is utilized in a systematic manner. Electronic yarn clearers mainly work either on

optical principle or at capacitance principles. The basic knowledge of EYC sensor

working is must require to user, with it’s various channel classifications.

Only a qualified & competent person from spinning mills who must aware for

base yarn Quality & characteristics, end use of finished yarn, customer & specific

requirements and ultimately fulfill the productivity requirements should be

authorized to set right and alter the EYC setting for maintaining it’s integrity and

avoid undue interferences. Usually person from QA/QC are most suitable for this

job.

Set right the EYC setting is a precious job and it should be done in a

systematic manner after taking many trials & studies with passions and with

analytical approach. Each & every channel setting requires separate – separate trials

& studies.

Dealing with Bad Quality / Off standard cops in a proper manner improve

the yarn Quality & winding productivity with byproduct as reduce hard waste. It

might be utilize for identification of rough spinning positions through proper

channelization and identification.

Finally standardization & documentation of EYC settings & trials is also

important for execution & follow-up of systems and future reference.

References : -

1. Yarn Master Zenit – Instruction Manual.

2. Uster Quantam 2 – Application Handbook.



Produced by : Mr. Sunil Kumar Sharma, Manager – QAD,

Mobile No. : – 09552596742, 09921417107

E_mail : - [email protected]

Loknayak Jayprakash Narayan Shetkari Sahakari Soot Girni Ltd.

Shahada, Dist. : - Nandurbar (MS)

electronic yarn clearers – a systematic approach

Technology

yarn diameter

yarn clearing

yarn defects

round yarn

yarn quality productivity

adequate yarn quality

measuring field

optical measuring principle