Uster shares insights to avoid claims from the start of the process
Producing consistent yarn quality is an everyday challenge – and a very difficult one. Detailed knowledge and understanding of the fibre raw material are absolutely critical to achieving the best possible yarn quality. To help spinners, Uster experts have put together guidelines for avoiding yarn irregularity claims in a special edition of the Uster News Bulletin.
Uster can say with greater certainty that the reasons for claims received by spinners have remained quite similar, at least in the past 20 to 30 years. Although the severity and distribution of the reasons may vary depending on the yarn’s final use, the most common factors can be identified. By analysing these factors and providing insights into the quest for operational excellence in spinning mills, the latest Uster News Bulletin No. 52 becomes a valuable tool for reducing yarn quality claims.
Laydown consistency – use data correctly
One factor that greatly affects the spinnability of cotton fibres and the quality of yarn is fibre fineness. Cotton has inherent natural variations, so fibre fineness (micronaire) is therefore the most important parameter to be controlled within required limits.
Optimal bale mixing aims at a consistently narrow micronaire range. Minimising variation in micronaire values, both across and within laydowns, is critical. Fluctuating micronaire values can lead to barre or inconsistent yarn strength, resulting in quality claims. To reduce risk, spinners use Uster HVI data for laydown management. Taking it further, many mills have integrated automated solutions such as Uster FiberQ, which use algorithms to control not only micronaire but also multiple other fibre characteristics. This reduces manual work, but more importantly, improves long-term quality from fibre to yarn by refining raw material selection.
Picture: Measuring fibre quality parameters with Uster HVI
Fibre process control – look closely at the blowroom
Uster’s experience shows that the reduction of neps is another of the most frequent challenges for spinning mills. Here, it’s better to avoid creating neps at the beginning of the process rather than trying to reduce them during spinning. Many spinners take steps in the blowroom and carding processes to tackle this issue.
In the blowroom, it’s about reducing waste and preventing an increase in short fibre content and neps. During cotton processing, the material is opened into tufts, with several stages of opening and cleaning aimed at removing impurities. But a side effect of these processes can be an increase in neps and short-fibre content due to mechanical stresses. Some spinning mills adjust card settings or try to remove broken fibres during combing, but a more effective and economical solution is thorough testing and blowroom optimisation.
To control blowroom and carding performance, Uster AFIS measurements are part of the routine test plan and are applied after machine maintenance or changes in cotton laydown recipes. These tests ensure optimal opening and cleaning at an appropriate waste level. Close monitoring of potential fibre damage is essential.
Processing statistics – track fibre characteristics
The processing charts in Uster Statistics track the fibre quality characteristics. Key parameters for neps, short fibres, and impurities are plotted through each processing stage. The accompanying graphic shows the typical increase in neps in the blowroom from bale to card mat, followed by a decrease after carding as neps are removed. Spinning mills can compare their own levels against the global standard. This allows a quick assessment of the situation, identifying areas of overperformance or potential improvements.
Picture: Fibre processing Uster Statistics – Total nep count (/g)
Various raw materials – one common goal
Process control is also important, especially when processing mechanically recycled cotton. Depending on the source of the recycled material and its opening method, the short fibre content may already be naturally higher when entering the blowroom.
Similarly, fibre damage can apply to man-made fibres, which initially have uniform cut lengths. Uster AFIS 6 can measure cotton as well as synthetic materials. With thorough quality management, spinners can identify fibre deterioration at source, before it results in yarn irregularity.
It’s clear that fibre characteristics significantly affect both spinnability and yarn quality consistency. Therefore, understanding fibre quality and how fibres are treated during the spinning process is essential right from the start. What is not measured cannot be controlled! However, this is only one element to be managed to avoid quality claims.
Uster has the technology, experience, and knowledge to foster a new level of consistency in yarn production. The company’s know-how is freely shared in Uster News Bulletin No. 52, which includes more chapters offering ‘best practice’ advice – from spinners for spinners – on how to take control of quality claims. Also free of charge is a wide range of application literature on https://360q.uster.com/home as well as the new Uster Statistics.
Uster News Bulletin No. 52 is available for free download. Besides a comprehensive introduction about claims in general and in comparison with the last fifty years, it contains eight sections on how to manage yarn irregularity claims. Download link: www.uster.com/unb52download
Furthermore, Uster offers a poster on the causes, effects, and solutions of fibre quality. Get your free-of-charge download! Download link: www.uster.com/fiberqualityposter
