Long detailed defects are particularly obvious on knitted fabrics and are also one of the key complaints from customers. In the long-detailed prevention and control process, only by accurately grasping the characteristics of defects and correctly analyzing the process and causes can we get to the point and prescribe the right medicine to solve the problem. The main reasons for long details can be referred to as follows:
01 The specific reasons for long details
The causes of long details are more complicated. In actual production, many factors can cause different types of long details. The following is a summary from three aspects: equipment, operation and technology:
(1) Equipment factors:
Final union:
1. The guide roller is not flexible in rotation and is easy to get stuck;
2. There are rust spots on the surface of the guide roller, and there are burrs on the collector, bell mouth, coiler and other parts, which are easy to cause damage;
3. The roller top roller is eccentric;
4. The surface of the top roller is sticky with cotton and wax, which is easy to get tangled;
5. The transmission key pin is loose, the gear is worn out, and it is knocked during operation;
6. Self-stop failure.
Roving:
1. The guide roller has burrs and flowers;
2. Burrs and cotton wax stuck to yarn channels such as spindle caps, hollow arms, rear bell mouths, etc. cause unexpected tension increases;
3. The upper pin is skewed and deformed, the pressing palm is deformed, etc., causing the sliver to be accidentally stretched;
4. The roving anti-detail device fails.
Spun yarn:
1. The guide bar has rust spots, burrs and hanging flowers;
2. Bell mouth burrs hanging flowers;
3. The rotation of the hanging spindle is inflexible;
4. The upper pin is skewed and deformed;
5. The top roller apron is damaged.
(2) Operational factors:
Final union:
1. Manually lift the guide roller;
2. There is a shortage of stock to feed, the auto-stop fails, and the lathe cuts the strips cleanly;
3. During the transportation and handling of the tampon, improper operation will cause damage to the tampon;
4. The joint is unqualified and too thin;
5. After winding the top roller, the defective strip could not be found.
Roving:
1. After the machine, the cotton sliver is twisted and split;
2. The joints at the front and rear of the machine are illegal and too thin;
3. The cotton sliver does not go through the normal channel and is wrapped around the guide fork.
Spun yarn:
1. During the unwinding process, the roving does not go through the normal channel and winds around the cradle axis, yarn guide rod, top roller, etc., which can easily cause accidental drafting.
2. The drafting area is poorly cleaned, the apron is pinched, the upper pin is lifted, and accidental drafting occurs;
3. The joint is unqualified (forced twisting).
(3) Technological factors: The main factor in technology is the influence of tension on the yarn.
Final union:
1. The guide bar tension of the draw frame is too large;
2. The coil tension is too high.
Roving:
1. The tension of the guide bar of the roving frame is too high;
2. The winding tension is too large;
3. The tension difference between large, medium and small yarns is too large;
In short, excessive tension in each process will provide more opportunities for accidental drafting. On the premise of ensuring normal production, it should be controlled to a small value.
02 Precautions for long details
1. Strengthen the management of temperature and humidity in the workshop, reduce the phenomenon of winding and blocking in each process, detect fluctuations, and make timely adjustments.
2. Strengthen equipment maintenance. The spinning channel should be smooth and clean, free of cotton, wax, impurities, and burrs. Key parts such as the upper pin and palm should be calibrated periodically. The gears should mesh well, and aging gears should be eliminated.
3. Improve the level of operation management so that new employees can have quality awareness and understand the basic quality requirements of yarn. There are no joints in front of and behind the machine. We must be aware of defects caused by thin strips and missing strands in the previous process.
4. Tighten the threshold value of long details in electronic clearing so that yarn defects with long details can be caught in time before leaving the factory.
5. Actively test the spinning process and choose the best tension configuration.
6. Develop a comprehensive inspection and assessment system for various factors that are prone to growth details. Responsibilities will be assigned to individuals, and violators will be punished.
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