1. Incoming raw material quality inspection
When sweater factories purchase raw materials, they must check the raw materials properly. The purchased raw materials must be sampled by the testing and laboratory department in a timely manner to conduct raw material inspection. Wool yarn that has not been inspected or does not meet the standards shall not be delivered for production.
1. Management requirements for wool yarn
(1) Before purchasing yarn, you should conduct an inspection and evaluation of the yarn supplier. It is best to have a relatively stable cooperating spinning mill to ensure thatConsistent yarn quality.
(2) After the wool yarn enters the factory, it is inspected according to the batch number and color number. The inspection items are mainly the weight of the large skein, linear density deviation, coefficient of variation of linear density, coefficient of variation of twist, coefficient of variation of evenness, single unit. Yarn breaking strength, strength variation coefficient, moisture regain, dye fastness, color difference, color flowers, color gradation, visual appearance defects, washing deformation, pilling, etc., and report any problems promptly. In order to modify the process parameters and ensure the quality of the finished product.
(3) Warehouses and production workshops should issue and pick up materials according to the limited number of process materials to prevent mis-issuance and improve the quality of finished products. They should also use specialized wool to save raw materials.
(4) The wool yarn in stock must be protected from damage, damage, insect infestation, mildew, yellowing and deterioration, etc. The wool yarn must be kept clean during operation.
(5) When using stocked wool yarn or processing wool yarn for production, a small amount of trial weaving should be considered to prevent the quality of the finished product from declining too much.
(6) In the process of using wool yarn, knitting factories must resolutely prevent yarns from different batch numbers from being knitted on the same shirt.
2. Methods of raw material inspection
(1) Hand visual inspection: used to inspect the appearance quality of yarn.
Visual inspection of appearance defects: Take random samples and weave a 60×50 weft flat needle and full needle rib sample fabric on the flat knitting machine to see if there are any defects such as nipping, horizontal stripes, cloud spots, and skew. The quality of wool yarn to prevent the occurrence of the above defects in mass production
(2) Instrument inspection: Use laboratory instruments to inspect the linear density deviation, strength, twist, etc. of the yarn.
After the wool yarn enters the factory, it is inspected according to the batch number and color number. The inspection items are mainly large skein weight, linear density deviation, linear density variation coefficient, twist variation coefficient, evenness variation coefficient, and single yarn breaking strength. , strong coefficient of variation, moisture regain, dyeing fastness, color difference, color bloom, color gradient, washing deformation, pilling, etc.
2. Quality requirements for yarn on the machine
1. Cleanliness
The wool yarn on the machine should be free of stray yarns, impurities, defects and oil stains. Impurities and defects such as unopened black and white wool, chemical fiber yarns, grass clippings should be removed.
2. Thickness and uniformity
Uneven thickness, roving, spun yarn, belly yarn, washboard yarn, etc. caused by poor equipment adjustment during the spinning process will be directly reflected on the sweater. In addition, the yarn joints will not come apart. The linear density deviation of general worsted wool yarn is <±3.8%, the linear density deviation rate of woolen wool yarn is <±4.8%, and the linear density deviation rate of high-grade wool yarn is 3. Twist
Due to reasons such as uneven thickness or different twisting equipment, it is often easy to cause the appearance of tightly twisted yarn, which is reflected in the poor appearance of the sweater surface. Carded sweaters must be milled and finished. The twist should not be too high and must be uniform. Generally, the twist unevenness of worsted wool yarn is controlled at <±8%-±10%, and the twist unevenness of carded wool yarn is <±10.%.
4． Color fastness
Color fastness has a great influence on the quality of finished products in knitting factories. Wool yarns should be dyed evenly and the color difference should not be low. The yarn is required to be smooth and soft at level 3.
5. Strength requirements
The breaking length of worsted pure wool yarn is >5200m, and the breaking length of worsted blended and chemical fiber yarn is >9500m.
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