The practice of rationally controlling combing noil rate
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Faced with today’s market crisis, the profit margins captured by spinning companies have been severely squeezed by many unfavorable factors. The cost of raw cotton has accounted for more than 60% of the total cost. Where does the profit come from? Only on the premise of ensuring the quality requirements of customers’ finished yarns can we scientifically and reasonably reduce the combing noil rate and produce spinning yarn that can meet customer quality requirements.
The combing noil rate and the yarn quality index are not a simple linear relationship. Within a certain range, as the combing noil rate increases, the short staple rate of the combed sliver decreases, and the yarn quality improves. Larger, and the noil rate increases to a certain level, the decrease in the short staple rate of the combed sliver tends to be gentle. Even if the noil rate is further increased, the elimination rate of the short staple rate in the combed sliver is very small, and the improvement of the yarn quality is also small. Not big.
According to quality requirements
In production, we must first accurately understand the customer’s requirements for product quality indicators, determine the minimum combing noil rate through rapid testing of yarn quality, and produce high-quality spinning yarn that meets customer needs, thereby reducing costs. , to maximize benefits. Before a new variety is put on the machine, more than two noil rate adjustment schemes can be used to conduct a quick trial spinning test of yarn quality. The economical low noil rate spinning operation can be selected from the results of the quick yarn quality test that afternoon. plan. The daily report of yarn quality can reflect the quality situation of the pre-spinning process 10 days ago. Rapid test spinning of a certain variety of yarn quality can be carried out on a regular basis to control the actual quality status of the current semi-finished product process and conduct timely testing. Adjust accordingly. Test data after many rapid trial spinnings show that an increase or decrease of 0.5 percentage points in the combing noil rate has little impact on the yarn quality, which also provides a basis for proper control of the combing noil rate.
The combing machine has an automatic adjustment function for the noil rate. When the noil rate fluctuates greatly, there must be something abnormal in the upstream process, for example: the short staple content of the raw material or the moisture regain of the raw material fluctuates. , the blowroom and carding processes have undergone large-scale process adjustments, sudden drastic changes in the outdoor airless environment, and unusual fluctuations in temperature and humidity, among other factors. Therefore, do not adjust the combing noil rate rashly and hurriedly. You should conduct an AFIS tester test in time, use static braking to find out the cause, and then make corresponding adjustments to avoid fluctuations in yarn quality. At the same time, a four-in-one emergency information feedback communication network for carding, combing, laboratory, production department, worker technicians from each department, and process engineers can be established to communicate information with each other in a timely manner and jointly solve difficult problems.
We conduct self-examination of the noil rate test more than twice a week to control the fluctuation curve of the noil rate. Usually, the noil rate fluctuates greatly on Monday, which may be related to the change in the moisture regain of raw materials caused by the shift on Saturday. The raw material pre-humidification treatment room can pre-humidify the raw material to reduce the chance of fiber damage due to poor fiber toughness due to low moisture regain of the raw material during the cleaning and carding finishing process. Strictly implement the fixed table supply system for each process, the reasonable matching system of large and small combing rolls, and the system of filling missing strips in front of the machine, increase the number of operations for cleaning the top comb intarsia, and reduce the table difference and eye difference of the noil rate of the combing machine, so as to Reduce yarn quality variation.
Properly configure the spacing
Orthogonal experiments on the pre-draw frame and combing machine by appropriately enlarging the roller spacing and the back draft ratio can help us seek the best process parameters for reducing sliver neps and short staple rates. Because although a small draft roller spacing can obtain a very good evenness CV% value level, it is by no means a good spinning yarn value. This may damage the long fibers, increase the short lint content of the combed sliver, and also increase the combing noil rate, increase the variation in yarn quality, and bring negative effects.
We need to look at the cylinder combing distance of the combing machine dialectically. The material of the German Schier cylinder gear is alloy steel. The gear has high sharpness, hardness and cleanliness. For example, it is used in the front area, tight point and middle of the S+UVARIO-COMB1295 cylinder on the E62 machine. The combing distances in the rear area are about 0.4 mm, 0.3 mm and 0.4 mm respectively, which are fully capable of combing the beard clumps with precision. It has a very high degree of fine combing of the beard clumps, resulting in a single fiberization effect. . If the carding distance of this type of cylinder is reduced, it will aggravate the fiber damage and increase the short staple rate and noil rate of the combed sliver. As for the domestic Jinfeng cylinder, the material of the finished tooth plate is imported steel belt, but the tooth shape, material and heat treatment process of the tooth plate need to be further improved. The sharpness and hardness of the tooth plate are still different from those of imported cylinder. The difference is that the ability to puncture and open fibers and remove neps and short lint is slightly worse.
Through a large number of comparative test results of adjusting the cylinder comb spacing, we found that the combing spacing of the domestic Jinfeng cylinder should be appropriately reduced, such as the front area is 0.3 mm ~ 0.35 mm, the tight point is 0.2 mm, and the rear area is 0.25 millimeters, and control the eye gap of each carding distance, scientifically manage the carding elements, and the yarn quality of the spun yarn can be greatly improved while the carding noil rate remains unchanged.��, which shows that the neps of spun yarn km+200% can be reduced by more than 20%, which is actually equivalent to reducing the combing noil rate.
In the second half of 2011, this initiative is indispensable to the continued stable quality of the yarns we spin and the successful introduction of low-nep varieties into production.
In production, we also need to scientifically establish a viewpoint on product quality positioning. Products at the 5% level of Uster’s Gazette are certainly good, but the price is high; products at the 95% level of Uster’s Gazette have a strong price competitive advantage. For example, for the NE50L/C40/60 products we produce, the combing waste can be controlled within the range of 14% to 14.5%, which can still meet the customer’s quality standards. Therefore, it is necessary to rationally allocate cotton according to the customer’s quality index needs, and scientifically and reasonably reduce the combing noil rate to an acceptable level that meets the middle and lower limits of the customer’s quality index, so as to maximize economic benefits with low transportation and management costs. . (Liu Yunwanchai Zhongbenan Xinhua of Shandong Liaocheng China Resources Fabric Co., Ltd.)
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