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  A genuine revolution in total testing

For more than 60 years, the USTER® name has been the global password to excellence in textile quality management. Modern spinning mills rely on USTER® testing equipment, know-how and expertise in their everyday operations. The USTER® STATISTICS provide the benchmarks by which quality is measured. And the entire textile community – from the cotton gin to the retailer’s counter – looks to USTER® to lead the way in setting new standards for cost-effective quality optimisation.

The changing demands of the textile industry worldwide mean that Uster Technologies is constantly innovating and updating its products, and this is exemplified by the steady progress made over the years with the USTER® TESTER family – arguably the most famous of its equipment ranges.

Often, these developments can be categorised as ‘evolutionary’ steps along the technological road. But the latest flagship model, the USTER® TESTER 5-S800, is different. It is no exaggeration to state that this represents a genuine and quite spectacular ‘revolution’ in the way textile mills test and optimise their production of yarns. There are several reasons for this view:

 --It tests at 800 m/min – twice the speed of any other tester.
 --It is purpose-designed to be part of a closed-loop ‘Total Testing’ concept, integrating both online and laboratory testing, following USTER®’s Think Quality principles.
 --It enables the production of results that are statistically more significant and more reliable, because of the high volume of tests it can process.
 --It is designed for the measurement of the remaining foreign fibres in yarns
 --The development of a sophisticated software allows the accurate measurement of slub yarns.

Benefits of high-speed testing

In developing the USTER® TESTER 5-S800, the capability for a 100% increase in testing throughput speed compared to existing testers was the key demand. Uster Technologies based this view on its close contact with customers and a detailed appreciation of their needs in an increasingly demanding quality environment. The design for this multi-purpose instrument for the analysis of slivers, rovings and yarns necessitated major improvements to the guiding elements for the test specimens, so that the system would be able to cope with the higher throughput speeds without the risk of disturbance to the samples.

The resulting high-performance testing system, as well as being the fastest on the market, also possesses the widest-possible range of test options. From its basic, well-proven original role as an evenness tester, the latest version of the USTER® TESTER now handles all the key parameters which can affect the quality of yarns and the way they perform in both woven and knitted fabrics. By using a unique combination of several sensor technologies – including both capacitative and optical – the USTER® TESTER 5-S800 examines and controls yarn quality in a way that no other system can. Mass evenness and imperfections, hairiness, diameter variations, density, impurities such as trash and dust – and the all-important foreign fibre contamination – are all measured and evaluated.

Naturally, these measurements and calculations are underpinned by the guaranteed accuracy and precision that Uster Technologies has built into its systems. This is further supported by total cor­relation with the USTER® STATISTICS data, the series of quality benchmarks which first appeared in 1957 and which have become indispensable to textile producers.

Example of savings:

If a spinning mill of 30,000 spindles randomly checks 100 bobbins per day, all the spinning positions are checked in 300 days at 400 m/min, but the mill can measure 165 bobbins per day at 800 m/min during the same period. Therefore, the mill only needs 182 days to measure all the spinning positions.

Figure 1. Higher-speed testing. The diagram illustrates the effect of testing at 800 m/min compared with 400 m/min.

Users of the USTER® TESTER 5-S800 can capitalise on its dramatically increased speed of operation in either of two ways:

Reduce the total time taken up by each testing procedure, and obtain meaningful overall results faster. Uster Technologies demonstrates that 67% more tests can be completed in a given time period, after allowing for setup and preparation of the bobbins.

In a well managed spinning mill of 30,000 spindles which want to get rid of outlier bobbins about 100 bobbins which are ejected by the winding machine have to be expected daily in the laboratory. In order to measure the additional 100 bobbins the following testing time is required:

Table 1. Example showing the saving in test time through the use of 800 m/min throughput speed

At 400 m/min the additional test time would be 2 hours and 5 min, ie, 67% more time is needed.

Allow each test procedure to run for the same amount of time as with a standard (400 m/min) testing installation. This effectively doubles the length of yarn which is tested in each process, and this has a significant impact on the statistical strength of the results. The length of the spectrogram is increased, and this enables periodic faults to be displayed, so that the depth of the quality analysis can extend back through earlier process stages to, for example, roving frames, drawframes and cards. In the example shown in Figure 5, the higher testing volume allowed the spectrogram to pinpoint a fault which could be traced back to an incorrect drawframe setting (peaks at lengths between 20 and 100 m).

Figure 2. Testing longer yarn lengths enables periodic faults to be detected

The full value of the USTER® TESTER 5-S800 really becomes apparent when it is used to create a closed-loop quality feedback system for the spinning mill, in partnership with the USTER® QUANTUM yarn clearers, which operate during the yarn winding stage to monitor and control every meter of yarn as it is produced, at normal industrial speeds. It allows the most important quality characteristics to be analysed instantly and any major problems to be pinpointed and eliminated.

The USTER® ‘Think Quality’ concept, which sets out a clear policy on all aspects of textile quality optimisation, emphasises the ‘Total Quality’ ideal as an expression of the perfect integration of online and laboratory testing disciplines. The combination of the USTER® QUANTUM and the USTER® TESTER 5-S800 is the ultimate solution, providing yarn producers with a decisive intervention at the point of manufacture, as well as an unrivalled facility to trace quality problems back to the source using sophisticated testing and analysis in the laboratory.

The USTER® TESTER 5-S800 is used, in this analytical process, to examine in detail all bobbins that have been rejected at the winding stage by the USTER® QUANTUM clearing operation (Figure 5). Spectrogram and diagram analysis of these yarns, in conjunction with statistical evidence about clearer data, can help identify the cause of the quality deficiency, whether this is a problem with the raw material, or a malfunction or component failure in a production machine.

Comprehensive test options

The scope of the testing capabilities of the USTER® TESTER 5-S800 is enormous. Recognising the importance to customers and downstream end-users of a full quality profile – tailored to the specific needs of the yarn type being produced – Uster Technologies has provided a comprehensive portfolio of special sensor options. No other textile testing system can match the range of options and the degree of detail available with the system.

It is widely acknowledged that variations in the hairiness of a yarn can cause unacceptable faults in a fabric and lead to unwanted claims and complaints. The OH Sensor for the USTER® TESTER 5-S800 provides an intelligent analysis of touch and wear, based on the internationally-accepted Uster hairiness parameter, and is now fitted to 90% of USTER® TESTER units installed.

Another unique feature available with the USTER® TESTER 5-S800 is the ability to measure a yarn’s surface structure, shape and density – so that the visual appearance of the yarn in the end-product can be confidently predicted, and complaints arising from fluctuations in the yarn geometry can be avoided. The OM Sensor uses two-dimensional measuring technology to control this vital quality aspect.

 --In finishing, 12% of customers’ complaints concerning colour variations and shadow-forming due to differences in diameter, density and shape
 --Surface structure and shape measurement is unique to USTER® TESTER 5-S800.
 --Yarn shape and density faults are not caused by mass variation and therefore only detectable with two-dimensional sensor technology.

shows a fabric made of yarns with different density which may happen if slow spindles cannot be detected on the ring spinning machine.

Trash, dust and seed coat fragments in yarns are said to be the cause of up to 25% of all downtime in weaving, as well as causing serious damage to knitting machines and needles. Yet these problems can be controlled by the OI Sensor of the USTER® TESTER 5-S800. This module measures trash, and dust particles directly in the yarn and allows remedial steps to be taken wherever required in the manufacturing sequence.

shows the check of the efficiency of the opening roller of two OE rotor spinning machines. The dust and trash particles in the sliver were measured with USTER® AFIS and in the yarn with the USTER® TESTER 5. Whereas the efficiency in the left figure is significant, there is hardly any removal of dust and trash in the case of right figure.

The FM Sensor provides for effective detection and classification of foreign fibres on the USTER® TESTER 5-S800 – eradicating potential problems which may not otherwise come to light until it is too late and the end-product has been rejected. The system offers fast and reliable detection and categorisation of foreign fibres, carried out at the same time as other quality parameters are tested.

The special characteristics of slub and effect yarns call for a demanding and different set of test parameters compared to conventional yarns. Since these yarns are still extremely popular in applications such as fashion denim, spinners need an effective and foolproof way of controlling their quality. In this regard, the USTER® TESTER 5-S800 is once again ahead of the field with its Fancy Yarn Profile, a software which applies a special measuring method to obtain all the relevant quality data for slub length, distance between slubs, and increases in mass – and presents this information in an easy-to-use series of graphic displays and reports.

Conclusion

 --The USTER® TESTER 5-S800 is the ultimate yarn quality control system, with the widest range of test options, reliable and accurate performance, and an amazing operating speed of 800 m/min.
 --Coupled with the online testing capabilities of the USTER® QUANTUM system, it forms a comprehensive, ground-breaking package that amounts to closed-loop yarn quality assurance.
 --For the first time, spinners can employ true ‘Total Testing’ and take complete control of their quality.

Gabriela Peters
Uster Technologies AG
Uster/Switzerland.

published August , 2008
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