Modern sensors and their capabilities for monitoring · 2019-06-16 · 50 years to detect and eliminate yarn faults on the winding machine, be-cause winding is the last process in

USTER® QUANTUM 3

Application Report

Modern sensors and their capabilities

to monitor all the bobbins on winding

machines

Textile Technology / 10 2007 / Version 2: 1.2013 / SE 600

THE YARN QUALITY ASSURANCE SYSTEM

2 (12) USTER® QUANTUM 3

Editorial Team:

R. Furter

U. Schneider

© Copyright 2013 by Uster Technologies AG. All rights reserved. All and any information contained in this document is non-binding. The supplier reserves the right to modify the products at any time. Any liability of the supplier for damages resulting from possible discrepancies between this document and the characteristics of the products is explicitly excluded.

veronesi\TT\Application Reports\USTER Quantum3 \ SE-600_Modern sensors and their capabilities for monitoring


USTER® QUANTUM 3 3 (12)

Contents

1 Introduction ............................................................................... 5

2 Tools to monitor 100% of all bobbins ...................................... 6

3 First task of a yarn clearer / Elimination of disturbing

thick and thin places ................................................................. 6

4 Second task of yarn clearers / Elimination of foreign

fibers .......................................................................................... 7

5 Third task of a yarn clearer / Separation of off-quality

bobbins ...................................................................................... 9

6 Fourth task of a yarn clearer / Feedback control system

to correct machine problems.................................................. 10

7 Summary .................................................................................. 11





1 Introduction

Up until now it is not yet possible to produce yarns without faults. There are

various reasons why the spinning process leads to the formation of disturb-

ing faults:

Machine parts which contribute to the drawing process are worn out or are out of tolerance.

Contaminations consisting of trash, dust, seed coat fragments and fiber fragments. Such contaminations are available at yarn guiding elements and in draw boxes of machines or in the air and are embedded into the slivers, rovings and yarns from time to time.

Foreign matter which is already available in the raw material and which could not be eliminated in the spinning process.

It is also well known in the textile industry that one single thread in a woven

or knitted fabric which does not fulfil the quality requirements can lead to a

second grade product.

As a result, many leading spinning mills do not only undertake efforts to

eliminate the seldom-occurring thick places, thin places and foreign fibers,

but also monitor the quality characteristics of yarns on the winding ma-

chines.

Table 1 shows the procedure to keep 100% of all bobbins under control:

Seldom-occurring yarn faults which can be

eliminated on the winding machine

Quality problems which necessitate to eject and sepa-

rate the bobbins at the winding machine

Disturbing thick places

Disturbing thin places

Disturbing colored foreign fibers

Disturbing white foreign fibers

Yarn evenness beyond critical limits

Yarn imperfections (frequent thin places, thick places and neps) beyond critical limits

Yarn hairiness beyond critical limits

Wrong yarn count

Table 1 Remaining quality problems in yarns which have to be corrected

Therefore, if a spinning mill has the intention to fight for a fault-free produc-

tion, the quality specialists have to direct their attention towards two prob-

lem areas:

The seldom-occurring faults which can be repaired on the winding machine

The off-quality bobbins with quality characteristics beyond critical limits



2 Tools to monitor 100% of all bobbins

With the introduction of the automatic winding machines in spinning mills

yarn clearers were developed which can monitor every bobbin. At the be-

ginning, however, the clearer was only designed for the elimination of dis-

turbing thick places. In the past 50 years the yarn clearer became a multi-

functional sensor with capabilities to minimize remaining quality problems

on the cone.

Fig. 1 shows such a multi-functional clearing system on a winding machine.

Fig. 1

Electronic yarn clearer in-

stalled on the winding ma-

chine

The electronic clearer consists of one or two sensors for all the tasks listed

in Table 1.

3 First task of a yarn clearer / Elimination of dis-turbing thick and thin places

Yarn clearing is always a compromise between efficiency and quality. On

one hand a spinning mill wants to eliminate as many thick and thin places

as possible to minimize quality risks. On the other hand every replacement

of a disturbing yarn fault by a splice reduces the efficiency of the machine

and increases the number of splices.

Fig. 2 and Fig. 3 demonstrate how the yarn quality can be visualized with a

modern yarn clearer (USTER® QUANTUM 3). The separation of the thick

and thin places to be eliminated from those which remain in the yarn can be

realized with the clearing curve (Fig. 2).

Fig. 2 shows how the clearing curve follows the green YARN BODYTM. All

the faults which are above the clearing curve have to be eliminated and

replaced by a splice.



Fig. 2

Disturbing and tolerated

thick and thin places. The

horizontal scale represents

the fault length, the vertical

scale the size of the fault

(mass increase).

Fig. 3

Size of the disturbing thick

place indicated by an arrow

in Fig. 2

4 Second task of yarn clearers / Elimination of foreign fibers

The contamination of cotton by foreign fibers is a headache for many quali-

ty specialists in spinning mills. Therefore, tremendous efforts are undertak-

en in many mills to eliminate foreign fibers.

Various trials in spinning mills have shown that the manual or automatic

elimination of foreign material can reduce the number of large foreign parti-

cles, but cannot reduce the amount of individual foreign fibers. Therefore,

the best method to conquer foreign matter is the procedure to keep away

the large particles from the card, but to eliminate the frequent foreign fibers

by a clearer.

Fig. 4 shows the relationship between the frequency and the size of foreign

particles and the domain of foreign matter recognition and elimination sys-

tems.



Fig. 4

Domain of foreign matter

elimination methods and

frequency of foreign materi-

al

Since the small foreign particles such as single plastic fibers, human or

animal hair, fragments of bird feathers, etc. have mostly a high frequency,

the cut rate of the electronic clearer is hardly affected when the automatic

recognition and elimination systems prior to the card are switched off.

Fig. 5

Foreign fibers

In many growth areas of cotton the packing material for bales is polypropyl-

ene. As a result, many bales are contaminated with polypropylene frag-

ments. Polypropylene fibers, however, do not absorb dyestuff and remain

white after dyeing. Such fibers cannot be recognized by optical sensors in

raw cotton yarns because there is hardly any color difference between cot-

ton and polypropylene. Therefore, a particular sensor was developed to

solve this problem.



Fig. 6

Polypropylene

5 Third task of a yarn clearer / Separation of off-quality bobbins

In a well-managed spinning mill a mostly small quantity of bobbins are pro-

duced every day which are beyond the pre-set standard with respect to

evenness, imperfections, hairiness, etc. Such quality problems cannot be

corrected on the winding machine because the fault is available throughout

the bobbin. Therefore, these off-quality bobbins have to be separated and

ejected at the winding machine.

Fig. 7 shows the monitoring of the hairiness with a modern clearer on a

winding machine. Yarn: Nec 30, combed, compact yarn, 160 bobbins, with

upper and lower warning limit.

Fig. 7

Monitoring of the hairiness

on the winding machine

All bobbins which exceed the warning limits will be ejected by the winding

machine.



6 Fourth task of a yarn clearer / Feedback control system to correct machine problems

An average ring spinning mill has a size of 20’000 to 30’000 spindles. In

comparison to other industrial activities the number of production positions

in spinning mills is very high. Therefore, a well organized spinning mill has

a repair crew which permanently improves outliers among the production

positions. The repair crew, however, needs input from the laboratory where

systematic quality analyses are made.

Fig. 8 shows the principles of operation in a spinning mill.

Fig. 8

The ejected bobbins are

analyzed in the laboratory.

Outliers are brought back to

the normal distribution.

The bobbins of individual spinning machines are marked to identify the pro-

duction positions where the ejected bobbins come from.

The ejected bobbins are brought to the textile laboratory where the quality

problems are evaluated. The findings are listed on an instruction sheet for

the repair crew. It is the intention to bring back the outliers to the normal

distribution Fig. 8.

The repair crew has to undertake the repair works at the machines (Fig. 9).

Successful repairs are reported back to the laboratory.

Fig. 9

Recommendations for a

systematic quality man-

agement

Bobbins which are recognized as having tolerated quality characteristics

will go back to the yarn batch. The outlier bobbins will be handled as sec-

ond grade bobbins.



7 Summary

The textile electronics industry has undertaken enormous efforts in the past

50 years to detect and eliminate yarn faults on the winding machine, be-

cause winding is the last process in the spinning mill where corrections can

be made. The electronic clearers on the winding machine are not only ca-

pable today to detect and eliminate seldom-occurring, disturbing yarn

faults. They also separate bobbins with quality characteristics beyond pre-

set limits. Therefore, spinning mills are approaching more and more the

objective of every quality manager: To permanently produce a fault-free

yarns of consistent quality.



Uster Technologies AG

Sonnenbergstrasse 10

CH-8610 Uster / Switzerland

Phone +41 43 366 36 36

Fax +41 43 366 36 37

www.uster.com [email protected]

Documents

Modern sensors and their capabilities for monitoring · 2019-06-16 · 50 years to detect and eliminate yarn faults on the winding machine, be-cause winding is the last process in