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Uster® Symposium 2003: From fibre to fabric Uster Technologies, Switzerland and Simag (Private) Limited., Pakistan arranged a symposium on February 8, 2003 at Sheraton Hotel, Karachi. Mr. Farooq Sumar, Chief Executive of Mohammad Farooq Textile Mills Ltd., presided over the Symposium. The Symposium started with recitation from the Holy Quran by Hafiz Tayab. Mr. A. A. Badi welcomed the large number of delegates attending the symposium. He briefly introduced the team of guest speakers, comprising of M/s. Wolfram Söll, Jürg Wiedemann, Joe Yankey and Andreas Tanner. 1. Presentation of Uster® Technologies Mr. Wolfram Söll gave an overview of the equipment and services offered by Uster® Technologies AG in fibre and yarn testing, yarn clearing, product testing, fabric inspection and other related areas as well as the composition of Uster® Technologies AG. Uster Technologies AG is a new company which took over from Uster® Luwa business division. The sponsors of the new company are Zellweger Uster Capvis, Quadriga Capital and senior management of Zellweger Uster. 1.1 Uster Statistics: Uster® Technologies AG started work in 1952, collected and tested samples of yarn from all over the world, compiled Uster Statistics which represent world-wide yarn quality standards. For product development, the company can provide highly advanced software. 1.2 Fibre testing Systems Fibre testing systems are developed and manufactured in Knoxville, U.S.A. On-line moisture control systems are installed in the advanced ginneries of U.S.A. to control R.H. and facilitate accurate cleaning and ginning of seed cotton. After ginning HVI-Systems are supplied for testing fibre characteristics of cotton.
1.3 Yarn Testing Equipment Yarn testing equipment is manufactured by Uster Zellweger, Switzerland. The sales network comprises of service centres and about 50 agencies spread all over the world. The yarn testing equipment includes sophisticated automatic instruments for testing evenness, strength, hairiness, imperfections, electronic yarn clearers both for ring and OE-spinning systems. 1.4 Uster® Fabriscan Two years ago Zellweger Uster introduced an Automatic Quality Inspection System for fabrics called `Fabriscan'. The system inspects grey fabrics at a speed of 120 meters/minute with the advantage of quick, objective and reproducible measurements of fabric characteristics. Concluding the overview of the equipment and services of Uster Technologies Mr. Söll stated that they also assisted their clients to finalise a recipe, install and operate a quality management programme systematically in their spinning mills.
After the overview Mr. Söll started his lecture on the subject of on-line monitoring of ring spinning process. Salient features and important points of his lecture are reported in the following paragraphs. 2.0 Sliver to yarn engineering Main focus of sliver to yarn engineering is manufacture of consistent quality yarn. The most important point is to understand the requirements of the clients completely. The product must posses characteristics on the basis of which it can satisfy stated requirement and meet specified performance criteria. In order to achieve these objectives following measures should be adopted. a. Continuous quality improvement Spinners must study the performance of their products at the downstream process of warping, sizing the weaving, consignment of yarn delivered by the spinner will satisfy the weaver if the end-breaks in weaving do not exceed one per 100,000 meters. This highlights the importance of adequate frequency of single yarn strength tests for which Uster® Tensojet is recommended. Tensojet tests yarn at a speed of 400 meters/min and produces 30,000 yarn breaks/hour. It simulates conditions of yarn loading at the air-jet weaving machine and, therefore, it is possible to predict weaving efficiency on the basis of yarn strength test results by Tensojet.
Tensojet force/elongation scatter plot revolutionises the traditional tensile testing reports. Every break is represented by a dot showing the respective force and elongation. The scatter points within the critical yellow area are weak places such as thin and thick places and places containing foreign fibres, trash particles, seed coat fragments etc. likely to break at the subsequent processes. Lower the number of weak points in the scatter plot better is the anticipated weaving efficiency and productivity, better is the price the weaver is prepared to pay. Pay back period for investment on Tensojet can be calculated by the spinner on the basis of expected improvement in yarn quality and price. The Opto-electronic sensors supplied with the fourth generation of Uster® Tester 4 facilitate complete assessment of yarn quality for the spinners. i. CS-Sensor- is a unique sensor for measurement of number of fibres per cross-section of sliver, roving and yarn. The test results enable a spinner to optimise speeds and draft settings of machines and eliminate periodic faults of rollers, gears etc. so that the number of fibres/cross-section remain constant and consequently quality of products is improved. ii. OS-Sensor - measures hairiness of yarn which indicates pilling tendency. If yarn hairiness H is 5 or lower the fabric will be less liable to pill. On the other hand if H is 6 or higher, the fabric will show higher pilling. Excessive hairiness of yarn also produces `barre' in fabrics, within specified limits. Hairiness is an excellent yarn characteristic and influences touch, feel and wear quality of the fabric. iii. OM-Sensor - it is optical multifunctional sensor and determines yarn diameter, the fine structure, round ness of yarn which indicates how the yarn will appear in fabrics. No change in mass but change in diameter causes loose surface variations which affect appearance of knitted fabrics. Problems in dyeability of fabrics originate due to shape, density and diameter variations of yarn. In the case of compact yarns these variations are much lower than those of ring-spun yarns and, therefore, problems in dyeability of fabrics are not encountered. iv. OI-Sensor - it is optical-impurities sensor which detects trash and dust particles in yarns and determines their number and size. Trash particles and dust in yarn lower its quality and it does not sell. Information on trash content in yarn helps the spinners to improve cleaning efficiencies of blowing and carding processes. In OE-spinning the spinboxes of a rotor machine with better clearing of trash and dust can be identified. In winding process high winding speed results in reduction of trash and dust content. Hence higher winding speeds are preferable provided other quality and process parameters are not adversely affected. Similarly, on the basis of information available from the OI-Senor, spinning mills can optimise their bale procurement and management system. v. FA-Senor - provides measurement of Gravimetric count. It is claimed that only Uster Technologies AG offer sensor for 2-dimensional yarn measurement. 3. Address of Mr. Farooq Sumar Addressing the gathering Mr. Farooq Sumar expressed regrets for leaving early. Today being the last date for hearing of the case against imposition of anti-dumping duties imposed by the European Union, he had to be in his office.
Mr. Sumar recalled that in 1968 their mill was not producing good quality yarn inspite of the fact that installed capacity comprised of Rieter machines. He called Mr. A.A. Badi who expressed surprise at the cartons of quality control equipment lying but not installed and not being used. Mr. Farooq Sumar ordered immediate installation and commissioning of quality control equipment. Within a couple of days the quality control equipment was operating and yarn quality problems were sorted out and solved! At the age of 19 years he realised the importance of the role of Uster quality control equipment in producing the required quality of yarn. In short, quality control equipment were the eyes and ears of a production facility. There were only 2/3 quality control laboratories in the textile industry of Pakistan in 1968. Muhammad Farooq Textile Mills became the first mill to cross OPS level of 6 OZS for 20 Ne in 1968. It was considered as the best managed spinning mill in the country. It become obvious to all concerned that higher productivity was highly correlated with better quality. Higher OPS could be achieved for a given count of yarn on the basis of lower value of U%. Concluding his address Mr. Sumar remarked that the spinning sector in Pakistan had come a long way but it had still a long way to go and start manufacture of new products such as speciality yarns, industrial yarns, tire cords etc. for which specialised training and educational facilities were required. Zellweger Uster is well known in Pakistan as supplier of first class textile testing and quality control equipment. 4. Quality management of cotton staple fibre After the address of Mr. Farooq Sumar, Mr. Joe Yankey delivered his lecture on the "Quality Management of Cotton Staple Fibre". He explained the scope of quality management involving the use of fibre testing instruments. 4.1 Uster HVI-Spectrum Uster HVI-Spectrum has been available since 1999. It is a completely automatic fibre testing system and does not involve any manual work. Window based software is used. A total of 1420 HVI units are operating in the world textile industry out of which 15% are HVI-Spectrum. The modules included in the system are: i) Colour and Trash The sequence of operations which is completely automatic is sampling, carding, brushing and measurement. The whole process of testing is completed in 30-35 seconds. Previously incandescent light bulbs were used which became very hot and affected the electronics of the system. These have now been replaced with patented eron Flash Tube, which facilitates improved colour and trash measurement. Measurement of moisture content of samples allows reduction in the conditioning time as well as variability of test results. With the results of tests for micronaire value it is possible to reduce micronaire variations from mix. to mix to 0.1 and reduce CV to less than 10%. By eliminating inclusion of immature fibres in the mix about 70% of the fabric barre' can be prevented. The remaining 30% causes can be prevented by controlling yarn hairiness excessive count and twist variations. The test for micronaire is very fast and, therefore, it is possible to test every bale included in a lot of 100 bales. Low micronaire values of Pakistani cottons are usually associated with immaturity. With HVI-spectrum fast testing of micronaire it is possible to identify bales with immature fibres and consume such bales for manufacture of yarns for special end-uses such as jeans, denims etc.
4.2 Uster® AFIS PRO- Uster AFIS PRO is a modular single fibre testing instrument. About 650 units of AFIS are operating world-wide out of which 10% are AFIS-PRO. The new model AFIS PRO - tests samples at a speed higher by 50% and test is completed in 2.5 to 3 minutes. Various modules provide measurements on the basis of which quality management is accomplished as under: · Neps module measures fibre and seed coat neps. The
latter type of neps are difficult to remove. The blowing processes increases neps where as
the carding removes neps, neps larger than 800/vm in size are visible in yarn. With the
information on the number of neps in card sliver it is possible to predict nep content of
yarn. · Length and Maturity Module provides accurate measurement of length distribution curve, histogram, maturity ratio, SFC (short fibre content) and IFC (Immature Fibre content). An increase of SFC in the card sliver indicates fibre damage and calls for the adjustment of the settings and speeds of the functional parts of the card. The combing efficiency can be improved by comparison of SFC in comber lap and combed sliver. Individual deliveries of comber can also be checked. By regular monitoring of SFC at the comber it is possible to reduce noils by 1% and maintain yarn quality at the same level.
· By regular monitoring of IFC, it is possible to eliminate fabric `barre'. IFC less than 8% presents no problem, some white specks may appear if IFC is from 9% to 12%. However, above 12% there will definitely be problem of white specks in fabrics. · Auto-jet module loads samples automatically into Uster® AFIS PRO. · Uster Qualiprofile™ integrated with Uster statistics for fibre properties provides a world wide tool in benchmarking of quality in yarn manufacturing. Concluding his lecture Mr. Yankey explained that USDA no longer
supplied calibration cottons. With ICC calibration cottons, the results of strength tests
were as follows. 5. On line quality monitoring of yarn clearing On-line quality monitoring of yarn clearing was the subject of the lecture of Mr. Jurg Wiedemann. The main points of his lecture are: 5.1 Uster® Quantum Clearer Uster quantum clearer combines the principles of capacitive as well as optical yarn clearing. Capacitive clearer measures yarn cross-section whereas the optical clearer measures yarn diameter. Uster Quantum clearer is backed by precise clearer curve setting according to specific mill requirements and produces a minimum of cuts for the required yarn quality, thereby ensuring peak machine productivity. It is a reliable and sensitive yarn clearer. With Uster CAY® software, the Uster ®Quantum clearer permits automatic setting, self adjustment and optimisation of the clearing curve. The Uster® Vegetable Filter also reduces foreign matter cuts by 20% to 25% by filtering non-disturbing vegetable foreign matter. Yarn hairiness measured by the quantum clearer correlates with the laboratory test results of Uster® Testers UT 3/UT4. Hairiness of yarn after cone winding increases as compared to that of cops. With Uster® Quantum clearer reliable detection and removal of foreign fibres is possible. Foreign fibres contamination in Pakistani cottons is about 8% while that of Nigerian cottons is 10%. 5.2 Uster® Classimat Quantum The Uster Classimat Quantum detects and classifies automatically seldom
occuring thick and thin places faults and foreign fibre in staple fibre yarns. At the end
of the test, it converts the fault frequency to a standard yarn length. This instrument
quickly provides an overall view of yarn quality by: 6. Yarn to Fabric Engineering Mr. Wolfram Söll delivered the last lecture of the symposium on the subject of yarn to fabric engineering. He briefly explained the role of Uster equipment in the management of quality during ring spinning and fabric inspection. Salient features of his lecture are: 6.1 Uster® Ring Expert Uster Ring Expert is a valuable tool in ON-LINE monitoring of the production, ring traveller speed, efficiency and machine stoppages. Approximately 60% of the fibre to yarn conversion cost is incurred in ring spinning process. It is extremely important to optimise yarn quality and machine productivity of this process. By detection and elimination of exceptional ring spinning positions slipping spindles which cause 30% of all end-breaks, produce inferior yarn, excessive waste, Uster Ring Expert facilitates ring spinning process optimisation. It is better to prevent than to eliminate yarn faults. On the basis of end-breaks per 1000 spindle hours, spinning mills are classified as follows for a given set of spinning conditions:- i) Top performance = 8 6.2 Uster® Fabriscan Uster Fabriscan incorporates state-of-the-art technology. It is an automatic fabric inspection system and fulfils following tasks at the rate of 120 m/min: · Learns the characteristics of the normal fabric
without flaws. The results of fabric inspection by the Uster Fabriscan system are reliable, reproducible and free from the subjective deficiencies of the manual fabric inspection, e.g. difference of opinion among inspectors about whether a fabric irregularity should be marked as a defect. Extensive use of screen display by all the speakers made their respective lectures very interesting. The participants asked many questions and received satisfac6tory replies from the lecturers. It was interesting to hear from Mr. Joe Yankey that whenever any standards relevant to textile technology are developed by any country, these are suitably integrated in the Uster Statistics e.g. the colour chart for Pakistani cottons developed by Pakistan Cotton Standards Institute has been included in Uster Fibre Statistics. The symposium ended with a vote of thanks by Mr. A. A. Badi. The participants were entertained to buffet dinner and received a gift packet each as they left the venue.
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