Influence of contamination detection on
yarn quality improvement
by
Dr.K.Ramachandralu ,
Professor of Textile Technology, P.S.G.College of Technology, Coimbatore, South India.

Introduction
Cotton fibre is a bounty given by nature to mankind,but unfortunately the quality of this wonderful fibre is marred by the problem of contamination. Contamination seriously affects the yarn quality. The contamination may be an impurity, which can affect the subsequent processes, product appearance and the product quality. The processing of contaminated cotton fibre results in poor yarn quality, with lower price.
It has become imperative to produce contaminant- free yarns, to compete effectively in the international market. The main contaminants are tar, leaves, feathers, paper, leather, grass and bark. As per ITMF (International Textile Manufacturer's Federation), survey of 2001, 22% of the Cotton worldwide has serious levels of contamination and the contamination level has been on the rise globally. From a study conducted by ITMF, five main and some additional sources of contamination were identified. The five main sources are strings made out of jute and plastic, fabrics made out of jute or hessian, organic matters such as leaves and leather bits, strings from cotton and finally strings from woven plastics, (i.e.), polypropylene and polyethylene. The additional sources are pouches of gutkha, human hair, etc., which are especially found in the cottons supplied from Indian ginning mills. Almost 39% of the Cotton is contaminated with organic matters like leaves, feathers, paper and leather, 30% with jute strings, 24% with polypropylene strings and with plastic films.

The reasons for the contamination are poor picking practices, poor storage facilities of kappas and poor ginning practices.The main headache behind these contaminant is, that they become visible only after the final finishing process. In general, the spinner has no options other than trying to remove them in the mixing stage engaging large number of workers. The problem of contamination could be effectively tackled by the contamination detectors, which have been introduced recently. The development of contamination detector has given a great relief to the spinners. Using this device, the contamination can be detected by sensing the colour differences between the contaminant and the cotton.

The popularly used contamination detectors are:
i. The Securomat SCFB from Barco-Pulsaar.
ii. The Vision Shield from Jossi (In collaboration with Rieter).
iii. The Securomat SCFO from Trutzschler.
iv. The Premier Fibre Eye from Premier Polytronics.
These equipment employ the principle of sensing the variation in the colour of contaminants from the fibrous cotton, in terms of variation in hue, saturation, and intensity of light by means of CCD cameras / photo- optic sensors and removing the contaminant instantly, by ejecting them out using air jet nozzles.

Sensitivity of these sensors could be varied depending upon the following factors:
· The type of cotton.
· The type of contamination present.
· The percentage of contamination.
· The placement of contamination detector.
· The velocity of cotton through supply pipe.
· The size of tuft.
· The width of chute.
· The volume of production.

In this paper, an attempt is made to study the effect of contamination detectors on improving the yarn quality. The study was conducted in a reputed spinning mill in Coimbatore by analyzing the Siro cuts made in the autoconer stage on the yarns made from regular material and contamination cleared material.

Materials and methods
For the purpose of examining the extent of contamination, the laps produced out of 120s mixing at four different levels of contamination detector setting- 1600, 1500, 1400 and 1300 were analyzed. The above settings refer to the different sensitivity levels.

To find out the efficiency of contamination detector in improving the yarn quality, five different counts namely 90s, 100s, 120s, 125s, 130s were considered. The number of cuts made by the Siro Cleaner attached to the Auto Coner were studied in case of the above yarns, manufactured before and after the installation of contamination detector in the blow room line. The above study was spanning over a period of six months and the average values of six months data were calculated.

The mixing details pertaining to different counts are given in Table 1. The improvement in yarn quality was estimated in terms of the reduction in the number of Siro Cuts achieved on the yarns manufactured after the installation of the contamination detector.

Results and discussions
The different varieties of contamination present in one full lap made of 120s mixing are given in table 2 and the total contamination in the lap at various sensitivity levels of detector settings is given in Table 3 and also graphically in fig.1.

The number of Siro Cuts made with respect to the different counts of yarn produced with and without contamination detector are given in the Table 4 and they are also depicted in the form of graph in Fig.2.

From the above table, it is clear that the installation of the contamination detector has significantly reduced the number of Siro Cuts in the yarn. The drastic reduction in the number of Siro Cuts made in case of yarns produced using contamination detector is a clear indication of the improvement in yarn quality with respect to the freedom from contamination. The percentage of improvement in case of all the counts spun using contamination detector is given in Table 5.

From the above table, it could be seen that the improvement works out to 40-45% approximately. This remarkable fiat is achieved in the yarn quality notwithstanding the total elimination of labour force engaged in the removal of contaminations at the mixing stage, resulting in the substantial reduction of labour cost and most importantly in the enhancement of yarn quality to a superior grade.

Conclusion
Normally in Indian cottons, the percentage of contamination will be higher than that of Egyptian and American cottons. Hence the usage of contamination detectors will be very much beneficial to the spinners. With the installation of such contamination detectors along with Siro Cleaners in Auto Coners, the spinner can ensure the supply of reasonably good quality yarns, free from contaminations, with consistency to his buyers. However, efforts to install such contamination detectors at the ginning stage will be more appropriate which will eliminate the problems of contamination at the root itself.

References
1. Apal, et al,:Indian Cotton: Present Status, Bottlenecks, ITJ; July 2003.
2. B. Vollheim; Detection of contamination in cotton Spinning Mills by Real Time Monitoring; Melliand; 4/2001.
3. International Cotton Contamination Survey, ITMF, Zurich, Switzerland, August 1999
4. S. Bala Murugan; Foreign Fibre contamination in Cotton, Premier Fibre Eye- the Right Choice; Asian Textile Journal; March 2003.

Global Textiles and Apparel in 2005 and Beyond:
Will China sustain its phenomenal growth?

Chinese textile and apparel output and exports surged following China’s membership of the World Trade Organisation (WTO). But growth may not be sustainable in the longer term, according to a report published in the latest issue of Textile Outlook International.
Chinese textile and apparel exports have surged since the country joined the WTO in December 2001. China has a number of weaknesses which could undermine its ability to hold on to its leadership after quotas have been eliminated at the beginning of 2005.
China’s textile industry has witnessed an unprecedented influx of foreign investment and imports of new machinery. But a large amount of the technology and equipment in the industry remains undeveloped. In weaving, for example, only 20% of looms are of the more advanced shuttleless type, which compares poorly with China’s rivals.
China also finds it difficult to compete in product innovation, branding, or rapid reaction capabilities – all of which are essential in modern textile and apparel markets. And China’s textile and clothing industry is too focused on quantity rather than quality.
The huge increase in exports from China since 2002 has been based mostly on cheap, low quality items. These are the kind of mass export items which attract defensive action. In late 2003, for example, the USA reimposed quotas on a number of textile and apparel product categories. The quotas were imposed under a special "safeguard" clause included in China’s WTO accession agreement.
Chinese Five Year Plan
The current Chinese Five Year Plan (2001-2005) aims to increase the added value of textile and apparel exports. But the reverse appears to be happening. In the case of Chinese textile and apparel exports to the EU and the USA, average prices are falling.
At the same time, production costs are rising. Wage costs are China’s traditional competitive strength. But in 2002 wages in large scale textile enterprises defined as concerns with a turnover of over Rmb5 mn (US$604,000) -- were double what they were in 1980 and are currently increasing by more than 5% a year.
Government efforts to distribute textile and apparel manufacturing more evenly throughout China’s regions do not appear to be working. In 2002 over 60% of all employment in the industry was concentrated in the five Eastern coastal provinces – Jiangsu, Zhejiang, Guangdong, Shandong and the Shanghai municipal region. These five regions were responsible for 74% of the gross output value and 81% of the export value of the industry.
China has made massive gains in world markets since it joined the WTO in late 2001, whereupon quotas were eliminated on a number of Chinese export items. But to maintain its leadership position in the more liberal, quota-free environment which will prevail in 2005 and beyond, it will need to speed up its transition from a large-scale textile industry into a strong one.
Courtesy: Belinda Carp, Textiles Intelligence, United Kingdom