Denim Weaving Technolog (3)

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Stretch Bamboo Denim Production Process Cases

Fabric specifications

Stretch bamboo yarn raw materials are mainly cotton wrapped spandex yarn, and medium and coarse special yarns with a yarn count range between 29 and 60 tex are the main ones; stretch bamboo denim is mainly medium-weight and heavy-weight denim, supplemented by thin denim.

Quality control of the main production process

Uneven thickness of elastic bamboo yarn is easy to produce in the weft storage device to send the weft to lead the weft is not smooth, the yarn is easy to produce the weft shrinkage in the cloth side of the two sections. When weaving, we should optimize the parameters of the machine, improve the weaving efficiency, reduce the weft shrinkage, hundred feet and other defects. The main measures are:

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  • In order to ensure the tightening of the weft yarn, to obtain a full and thick fabric effect, the use of “higher back beam, large tension, early opening” on the machine process.
  • Select the appropriate shuttle height, reduce the cloth thinning road, reduce the warp yarn breakage.
  • Early opening time of the waste side warp yarn, make it interweave with the weft yarn earlier, increase the holding power to control the rebound shrinkage of the waste side weft yarn. At the same time, stretch denim is easy to produce the phenomenon of rolled edge, therefore, the width of the edge should be appropriately widened.
  • Appropriately increase the amount of waste side weft yarn retention, the amount of waste side weft yarn retention increased from 4cm to 5cm, increase the control of twisted warp yarn on waste side weft yarn, prevent the weft yarn from rebound slippage, eliminate the side weft shrinkage, side hundred feet and other defects.
  • Ensure that the weft yarn tension is uniform and sufficient, so that the weft yarn is fully elongated, effectively reducing weft shrinkage, weft breakage defects. Different weft varieties choose more than two weft storage, respectively, to adjust the weft tension, to meet the needs of a variety of staggered weft introduction. Appropriate and uniform tension can also prevent the weft yarns from twisting and weaving into the cloth to produce weft shrinkage, resulting in the cloth surface bubbles and bad edges.
  • The speed of the loom is reduced by 12% to 18% compared with the conventional denim varieties; the temperature and humidity of the workshop are appropriate, and the relative humidity is controlled at 70% to 75%.

Weaving process

Weaving on imported Bejaral PGM-190 flexible rapier machine. Weaving speed 330r/min, opening time 305°~315°, upper tension 1.3kN, back beam (double back beam)/height×depth 4×2, height of warp stop frame 220mm.

Bamboo Pulp Fiber Denim Weaving Process Cases

Fabric specifications

Bamboo pulp fiber (58tex+58tex bamboo) × (58tex+58tex bamboo) 315×196.9, organization: 3/1 right twill, fabric weight 305g/m2, width 150cm.

Production quality control

The weaving process of “small tension, small opening, low back beam” is adopted. Small tension, small opening is conducive to reducing breakage, but the small opening of the shuttle mouth clarity is poor, in order to ensure that the opening is clear, to minimize the difference between the upper and lower layers of warp yarn tension, so the position of the warp stop and the back beam should be lower than the cotton fabric, so as to improve the clarity of the opening to reduce the breakage of warp yarns, but also conducive to the weft yarns normal flight, reduce the weft blocking stop platforms. Bamboo pulp fiber yarn is easy to elongate, so after stopping or removing the cloth is particularly easy to drive cross-stalls, so it should be reasonable to develop the warp position line, at the same time to improve the brake sensitivity and reduce driving marks. Bamboo pulp fiber yarn denim in weaving production is most likely to produce rotten edges, side support defects such as side defects, production should focus on controlling the quality of side support installation and the quality of the bolt machine. Can be replaced with fine-toothed side support ring, in order to avoid the emergence of a large number of side support defects. Bamboo pulp fiber yarn denim weaving workshop temperature and humidity is very sensitive. When the relative humidity is low, the strength of the yarn is good, good elasticity, good abrasion resistance. But the relative humidity is too low and will increase the broken head. Workshop temperature control at 25 ~ 28 ℃ or so, relative humidity control between 60% ~ 65% is appropriate.

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Weaving process

Weaving process parameters on K88 rapier loom are as follows: warp yarn tension 3000N, back beam height -5 scale, 138mm before and after back beam, warp stop frame height 122mm, 131mm before and after warp stop frame, heddle leveling time 305°, stopping position 320°.

Denim Weaving Defects

Hundred Feet Defects

Hundred feet refers to the twill fabric organization is missing one or several weft yarns when the formation of defects. The causes of the quality of the weft yarn: such as the weft yarn strength is insufficient, easy to be blown off by the high-pressure airflow when the weft is induced, or the yarn thickness is not uniform, the weft is induced on the coarse knots or details of the yarn is easy to be blown off resulting in a hundred feet; the weft stopping device is not sensitive; blocking the platform workers in the treatment of weft stopping the platform when the operation is not appropriate or not carefully operated.

Driving Marks

Driving marks are common defects in the production of denim, the main reason is that the denim organization is usually more twill, weft tightness; and denim warp yarn is dyed before weaving, the warp yarn weaving before a longer path, yarn elasticity loss. And denim made into garments are to be washed by the garment, weaving process produces a slight driving marks in the washing process will be more obvious. Driving marks include driving thin weft, dense road and warp shrinkage wave pattern defects. When driving the weft force is insufficient, it is easy to form a thin and dense road on the cloth surface. General air jet looms are equipped with fast and slow start function. The fast start function enables the first weft to strike the weft forcefully, which helps to reduce the driving marks. When weaving, the weaving machine can be set to fast start or slow start after a warp or weft break, depending on whether a thin or a dense path is formed. Changing the starting angle of the weaving machine can also effectively eliminate thin and dense loops.

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Loosening and tightening the warp

Denim due to uneven warp yarn tension so that part of the warp yarn tension than the other warp yarn tension is small, so that this part of the warp yarn in the fabric shows loose, so that the formation of loose warp. The loose warp in denim has excessive protrusions, resulting in darker color traces. Due to the uneven tension of warp yarns in the fabric, the tension of one part of the warp yarns is higher than that of other warp yarns, thus making this part of the warp yarns too tight in the fabric to form tight warp. Tight warp part of the warp yarns of the flexural wave height decreases, resulting in an increase in the proportion of white weft exposure, the formation of white traces on the fabric. The causes of loose warp and tight warp are:

  • the pulp shaft winding process due to the uneven reed arrangement, the warp beam back winding tension is not uniform, uneven stranding and other reasons, so that the warp beam on the whole width of the warp yarn loosening and tightening degree is not consistent, in the weaving machine to produce the whole width of the loose warp and tight warp defects;
  • The inverted broken head on the weaving shaft produces loose warp defects on the cloth surface due to the uncontrolled tension at one end during the weaving process;
  • Produce loose warp, tight warp causes such as stranded head, inverted broken head and sizing spot is not treated or improperly treated, resulting in changes in the tension of the single yarn, the formation of loose and tight warp.