Scope of Quality Assurance and Testing in Spinning

Scope of Quality Assurance and Testing in Spinning
S. M. Hossen Uzzal
B.Sc. in Textile Technology
Monno Fabrics Ltd. Manikgonj
Email: uhossen@gmail.com



Yarn spinning is a process of making or converting fiber materials into yarns. It is a complex branch of textile. Here the task of quality control starts from the raw material. At first when the raw cotton arrives, the lab boys collect samples from each bale and give respective numbers to each bale. Then the samples are tested in H.V.I. machine. From the obtained results, the bales are categorized in suitable categories for bale management and stored in the warehouse. Then the raw cotton is fed to the blow room through the bale management system. The bale management system is a vital task of the Quality Assurance department.

In blow-room, the fibers are opened and cleaned by beaters. Here if over beating takes place then there is a chance of fiber damage. So, the QA department tests cotton sample before and after every beating position to check the cleaning efficiency and fiber damaging. From there, necessary actions are taken. Different wastes that are collected at the fiber deposition plant of blow room are also studied to assure proper removal of trash particles as well as least possible wastage of cotton fiber. Also the QA department monitors the setting and performance of the contamination separator of the blow room.

Blowroom
Blowroom
In the carding machine the Ktex of the produced sliver is checked once per shift. The performance of the carding is evaluated by testing m/c and sliver of the carding in USTER-5 and AFIS. From there the Neps Removal Efficiency, SFCw, SFCn, UQL etc are seen to evaluate its performance and necessity of gauge change, grinding and wire change of cylinder, licker-in and flat is determined. The card sliver is tested in USTER-5 once per shift to test its Unevenness (U%) and coefficient of variation of mass (CV%).
Carding machine
Carding machine
In breaker draw frame, mainly the grain/yd of sliver is tested once per shift. Other than this also the sliver is tested in USTER-5 to determine the length of the fibers in strand to set the proper roller gauge in the roller drafting zone. The breaker sliver is tested once per shift in USTER-5 to determine its Unevenness (U%) and coefficient of variation of mass (CV%).
Draw frame
In lap former, the lap thickness is measured mainly.
The Comber is a very crucial machine. Its performance plays a vital role on the quality of the combed yarn. So, the performance of the comber is assessed by testing the material before and after it. From there the nep removal efficiency of the machine is determined. Also the noil is tested to see whether long fibers are being wasted during the processing. From there, the necessary changes in the setting of the machine is carried out. The grain/yd of combed sliver is checked once per shift. The combed sliver is also tested once per shift in USTER-5 to determine U%, CV% etc and any periodic faults from the spectrogram.

Comber machine
Comber machine
The finisher draw frame is a very vital machine in respect of quality control. As it is the last machine fitted with an auto leveler, it is the last step where the mass variation of sliver can be maintained. For this here the grain/yd of sliver is checked at every hour. If the variation of the finisher sliver can be controlled, then there will be less variation and imperfection in the yarn. Also the calibration of the auto-leveler is done when necessary by the QA department. The finisher sliver is tested once per shift in USTER-5 to determine its U%, CVm%, CV3m% and to see whether there is any periodic fault from the spectrogram.

In case of testing of carding, breaker draw frame and finisher draw frame, a schedule is maintained so that all the machines are tested within a fixed period of time.

In simplex, the hank is mainly tested once per shift. Also the roving is tested in the USTER-5. A schedule is maintained so that all the spindles of simplex machines are tested over a period of time.

Simplex m/c
Simplex m/c
The yarn of ring frame, rotor machine and auto-coner are tested to determine their count. This test is carried out at each shift for each count and lot. Testing is carried out in USTER-5 Tester in the same manner to determine the U%, CV%, Relative count, +50% thick places, -50% thin places, +200% Neps (ring yarn), Imperfection index, hairiness, standard deviation of hairiness, periodic faults etc. From there necessary actions are taken to eliminate or reduce the faults. The CSP (Count Strength Product) of the yarn are also tested to determine the bundle yarn strength which is very important for knitted fabric. The TPI (Twist Per Inch) of yarn is tested at the beginning of each lot.
Ring frame
Ring frame
The setting of drafting gear in drawing frame, simplex and ring frame is given by the QA department and is implemented then by the maintenance department. The QA department on the basis of trial and experiment does the selection of proper roller gauge and spacer in the drafting zone of simplex and ring frame. Also the setting of the EYC (Electronic Yarn Clearer) is determined by the QA department. This ensures that most of the faults that are present in the yarn are cut out during winding on paper cone and fault free yarn are delivered to the customer.

The moisture content in the yarn packages after heat setting are also tested by the QA department. Thus the proper time of heat setting can be maintained to deliver yarn with required amount of moisture content.


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