Foreign fibre contamination in cotton
Premier Fibre Eye - the right choice
by
S. Balamurugan
Premier Polytronics Pvt. Ltd., India

Introduction

Today's market demands an absolutely contamination free yarn. Cloth strips, woven plastic, plastic film, jute or Hessian, Organic matter like leaves, feathers, paper and leather, Oily substance/chemicals like grease, oil, rubber, stamp colour and tar etc. are the unwanted contaminations in the final fabric

   
Customer claims on account of contamination can easily wipe out the profits of the Spinning mills . So there is an obvious increase in awareness of these contaminations and the spinning mills have tried to educate the cotton supply chain to change several practices like packing of cotton bales with cotton fabric instead of jute or hessian bags. And the spinners themselves are equipping with more devices and better practices to reduce the level of contamination.

Global Trend

However, globally the contamination level is on the increase. As per ITMF survey of 2001, 22 % of the Cotton worldwide has serious levels of contamination.

Almost 39% of the Cotton is contaminated with organic matter like leaves, feathers, paper and leather, 30 % with jute strings, 24% with polypropylene strings and with plastic films.

Indian Cotton in 2001 remained as one of the most contaminated according to ITMF - three times higher than the world average. Atleast 8 varieties were found highly contaminated. Especially the H4, LRA, J34, S4 and S6 were highly contaminated and the trend seems to be increasing.

Present methods of Contamination Removal - Most of the mills are manually checking for contamination after opening the bales. The normal practice is to allot 1 bale per person for the segregation. A 25,000 spindle mill, for instance would employ 50 - 60 persons for contamination picking. Few more workers are also assigned on either side of the bales along the bale plucker to pick the contamination.

Though the above methods are helpful, mills have come to realise that this is not sufficient. So many mills today are equipping with Automatic detectors at the Blowroom.

Automatic detectors - Normally a detector would be placed in a sequence of the Blowroom and it would have a set of Photo optic sensors or CCD Camera on either side of the Cotton flow. And a set of nozzles to eject the detected contaminations. Irrespective of the technology used whether CCD or optic photosensor, the performance depends on optimising the various elements involved and in any case the efficiency is about 60   75%.

Picking - along the bale plucker

Premier Fibre Eye - The new generation Fibre Eye identifies foreign material with an array of 160 high speed, high sensitive photosensors and ejects the material with high speed air nozzles. The technology is very efficient and at the same time cost effective. Premier Fibre Eye reliably detects all types of foreign materials including jute, hair, paper, polypropylene, feather, leaves, coloured threads, dyed fibres, cloth bits and sticks. The signals from the individual photosensors are processed through an intelligent custom designed software which ensures foolproof detection and elimination of the foreign material. After detection of the contaminants, the contaminated material is ejected into the waste chamber using 32 high speed air nozzles. 3 or 5 nozzles are activated at a time resulting in minimum good fibre loss, while at the same time effectively ejecting the detected contaminants.

Fibre Eye

Premier Fibre Eye has an automatic calibration mechanism for adjustment of the detection threshold during regular operation based on the base cotton material. This ensures effective removal of contaminants at all times irrespective of the natural variations in the cotton colour. The efficiency of detection depends to a great extent on the proper upkeep and maintenance of the equipment.

Premier Fibre Eye is uniquely designed to facilitate easy maintenance. Modular lighting section enables easy cleaning of the lights. Other dirt prone areas are also easily accessible for quick cleaning.

Location and number of detectors - There was a school of thought suggesting to place 'the detector' in the beginning of Blowroom so that the contaminations are not broken down into multiple smaller fragments. But with more installations and actual experience, almost all the manufacturers are in favour of locating it at the end of the line. Smaller the tuft size and lower the production rate better is the detection efficiency.

Double Value with Premier Fibre Eye - In order to ensure the maximum removal of contamination, Premier recommends two Fibre Eye systems in each line, one in the beginning and the other after the fine beater. This configuration enables the highest level of detection and yet assures the most economical solution for foreign fibre cleaning.