How to reduce long detail defects in yarn

2022-04-26   Pageview:448

Long detail defects are especially obvious on knitted fabrics, and it is also one of the key issues of customer complaints. 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, prescribe the right medicine, and solve the problem. The main reasons for the long details can be referred to as follows:

1. The specific reasons for the long details:

The reasons for the generation of long details are more complicated. In actual production, many factors can cause different types of long details. The following summarizes the three aspects of equipment, operation and process:

(1) Factors in equipment:

Last merge:

1. The rotation of the guide roller is inflexible and easy to beat;

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 hang flowers;

3. The roller top roller is eccentric;

4. The surface of the top roller is sticky with cotton and wax, which is easy to tangle;

5. The transmission key pin is loose, the gear is worn out, wax emulsion, and the operation is paused;

6. Self-stop failure.


1. The burr of the guide roller is hanging flowers;

2. Unexpected tension increases due to burrs and sticky cotton wax in the yarn channel such as spindle cap, hollow arm, rear bell mouth, etc.;

3. The upper pin is skewed and deformed, and the pressing palm is deformed, so that the sliver is accidentally drafted;

4. The roving anti-detail device fails.

Spinning yarn:

1. The guide bar has rust spots and burrs hanging flowers;

2. Bell mouth burr hanging flowers;

3. The ingot rotation is not flexible;

4. The upper pin is skewed and deformed;

5. The apron of the top roller is damaged.

(2) Operational factors:

Last merge:

1. Lift the guide roller artificially;

2. Lack of stock feeding, self-stop failure, and unclean lathes;

3. During the transportation and handling of the sliver, improper operation will cause damage to the sliver;

4. The joint is unqualified and too thin;

5. After wrapping the roller, the defective strip could not be found.


1. The sliver is twisted and split after the machine;

2. The illegal joints at the front and rear of the machine are too thin;

3. The sliver does not pass through the normal channel and is wrapped around the guide sliver fork.

Spinning yarn:

1. In the process of unwinding, the roving does not pass through the normal passage, and appears around the cradle shaft, around the yarn guide rod, around the top roller, etc., which is easy to cause accidental drafting.

2. The drafting area is poorly clean, the apron is caught, the upper pin is lifted, and the drafting is unexpected;

3. The joint is unqualified (strong twist).

(3) Factors in craftsmanship:

The main process is the effect of tension on the yarn.

Last merge:

1. The tension of the guide bar of the drawing frame is too large;

2. The coil tension is too large.


1. The tension of the guide bar of the roving frame is too large;

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, and under the premise of ensuring normal production, it should be controlled less.

2. Precautionary measures for long details:

1. Strengthen the management of temperature and humidity in the workshop, reduce the phenomenon of entanglement and blockage in each process, and adjust in time if fluctuations are found.

2. Strengthen equipment maintenance, the spinning channel is smooth and clean, free of cotton wax, sticky impurities, burrs, the key parts such as the upper pin and palm should be corrected periodically, the gears are well meshed, and the aging gears should be eliminated.

3. Improve the level of operation and management, so that new employees can have quality awareness and understand the basic quality requirements of yarn. Avoid joints before and after the machine. For the thin strips, missing stock feeding, etc. caused by the previous process, there must be a sense of catching faults.

4. Tighten the threshold value of long details of electric clearing, so that the yarn defects of long details can be caught in time before leaving the factory.

5. Actively try spinning and choose the best tension configuration.


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