Content - Perfectly clear: eradicating defects in spun yarn
- March 08, 2012
Perfectly clear: eradicating defects in spun yarn
Why the USTER® QUANTUM 3 has become an indispensable aid to quality and productivity in modern spinning mills.
The winding machine is the final stage in the spinning process – the last chance to remove any faults in the yarn before it goes out to the customer. That means it is essential that any disturbing yarn faults are effectively removed by yarn clearers on the winder. The USTER® QUANTUM 3 provides the ideal solution, enabling spinners to deliver optimum quality while maintaining productivity.
Unfortunately, it is impossible to produce a perfectly fault-free yarn in a spinning mill. Raw material inconsistency, wear to critical machine components such as card clothing, incorrect drawbox regulation and contamination by dirt and fly are among the most common difficulties.
Now, underpinned by 50 years' experience in yarn clearer innovation, the third-generation USTER® QUANTUM is a state-of-the-art instrument which can guarantee the required quality. Its unique Smart Clearing Technology allows users to see the visualized yarn quality and based on this to optimize the clearing process what results in a continuously improved performance. The clearing settings can be adjusted in real time, to meet the required level of quality and avoid unnecessary cuts which would affect productivity. The USTER® QUANTUM 3 gives spinners advanced control options for dealing with both contamination and mass defects in the yarn during winding.
The yarn body
A key element of the USTER® QUANTUM 3 is the 'yarn body' concept. This allows the removal of only the really disturbing faults, while also optimizing the number of cuts. The yarn body is a new visual parameter – effectively a 'picture' of the yarn and its quality characteristics. The concept takes account of the yarn unevenness; the count; raw material; and the spinning process used. For example, carded yarns exhibit a wider yarn body than combed and compact-spun yarns, because of their higher irregularity. Similarly, fine count yarns show a wider yarn body than coarse yarns.
The USTER® QUANTUM 3 displays the yarn body graphically as a dark green area representing the 'real' yarn body and a light green area showing variations in it (see figure 1). Sivakumar Narayanan, Product Manager of Yarn Clearing within Uster Technologies says: “The yarn body is quickly recognized as an indispensable tool by mill managers who start to work with it. They find it extremely useful in helping to establish optimum clearing limits, not only for thick places and thin places, but also for yarn count variations and deviations.”
Fig. 1: Yarn body displayed with the USTER® QUANTUM 3
The main functions of a modern yarn clearer are the elimination of seldom-occurring disturbing yarn faults such as thick places, thin places and foreign fibers. With conventional yarn clearers, spinning managers need to spend a lot of time and effort finding the right clearing limits for a new article. The USTER® QUANTUM 3 handles this automatically – within only a few minutes. This unique feature, called Smart Limit, suggests optimum clearing limits based on the yarn body. The proposed value can easily be optimized to suit individual requirements for quality and productivity. Every change to the settings will automatically produce a new cut forecast.
With its Smart Clearing Technology, the USTER® QUANTUM 3 offers even more. The system can minimize the number of cuts by identifying non-disturbing faults. For example, it distinguishes between disturbing foreign fibers and non-disturbing vegetable matter – cutting only where yarn quality would be affected.
Based on many years' experience in foreign matter detection, Uster Technologies has identified opportunities to improve productivity for yarn manufacturers by differentiating between types of foreign materials in cotton. The fact that 'not all foreign matter is disturbing for all applications' is the key point. For example, dark-colored foreign fibers may be disturbing only in light-colored fabrics – and vice versa. And cellulose-based contaminants or 'vegetable matter' will not usually be disturbing in applications where the yarn or fabric is to be bleached and dyed.
The cost of a single yarn cut
How expensive is a clearer cut on the winder? USTER has developed an internal tool to demonstrate the financial impact of clearer cuts on the winding machine. The tool shows the importance of setting correct clearing limits to spinners quite plainly. In the example for a Ne 40 yarn (see figure 2) vegetable clearing reduces the cut level by 1 cut per 100 km for all machines without changing any other settings. This alone will result in savings of over USD 40,000 per year in a typical 600-position winding installation.
The example shows impressively that saving cuts leads to cost efficiency. Polypropylene clearing is another important optimization possibility of the Smart Clearing Technology to deliver the requested yarn quality aiming at the same time to keep the number of cuts as low as possible. Overall, the USTER® QUANTUM 3 has a range of unique clearing features which support spinners in their drive for precise quality balanced with optimal productivity.
Fig. 2: Screen shot of internal calculation tool