Non-uniform sparse weft is a phenomenon frequently observed during weaving, and it can be caused by a variety of factors that involve a wide range of issues. The following paragraphs will explain the reasons behind the occurrence of both non-uniform and regular sparse weft.
1.The cause of the irregular and sparse wrinkles in a weave is due to the non-uniformity of the thread.
（1）The net is hanging incorrectly. This situation often occurs when weaving a twill net due to the net being skewed and hung off-center, resulting in a sparse path on one side and a dense path on the other after hanging the net.
（2）When weaving twill net, there is a certain amount of netting on the roller, and when the roller is released halfway and the netting is tightly rolled up to continue weaving, a half of the netting will appear loose at the weaving edge. One side is sparse and the other side is dense.
（3）When the position of the chest roller is not horizontal, or the installation position of the net roller is uneven, it is common for one side of the net to be loose while the other side is tight when hanging the net.
（4）After the sword belt runs empty, the incorrect treatment of the weft thread density results in sparse and dense areas.
（5）There is a sparse area at the junction of the soft and hard threads. A sparse area appears when the hard thread is woven in behind the soft thread, and a dense area appears when the soft thread is woven in behind the hard thread.
（6）The cardan shaft support is vibrating and when parking, a crack appears on the mesh. For example, wear of the various connecting shafts in the joint causes them to shake, and the crankshaft has a large radial swing within the tile. Loose bolts connecting the walking beam and the cardan shaft support foot, as well as breakage of the cardan shaft support bottom plate, can all cause vibration when the cardan shaft is engaged.
2.The reason for the regularity of sparse channels in weft.
(1)When the accuracy of the wire rolling adjuster is not high enough to meet the precision requirements of the specification for the woven metal mesh, it will inevitably result in a sparse channel.
(2)When weaving a high mesh net, if the tension of the net cannot be kept consistent at all times, a regular sparse path will appear.
(3)The teeth and shaft of the roller network regulator are entangled with fibers and debris, which affects the consistency of rotation and results in sparse pathways.
(4)The frictional force between the brake frame and the brake fixed wheel is small. Under the maximum tension during warping, intermittent sliding occurs between the brake fixed wheel and the brake frame, causing uneven warp length and sparse weaving.
(5)Sending the warp ratchet and sending the warp top teeth wear out over time, sometimes causing slippage, resulting in inconsistent warp length and causing irregular woven fabric.
(6) The shaft key on the overrunning clutch is loose and has come out of place.
(7) There is local slipping during the rotation of the overrunning clutch.
(8) The meshing of the conical teeth is too loose and there is a tooth skipping phenomenon during spool winding.
(9) The swing angle of the spool is too small.
(10) If the bearing seat on one end of the crankshaft is loose on the wall panel, it will cause sparse and dense channels on one side of the mesh.
(11) The wear of the gears that feed into the regulator causes looseness and excessive play, so it cannot strictly control the length of each feed, resulting in sparse and dense channels.
(12) When weaving twill mesh, if the position of the reed is too low, regular sparse channels will appear, that is, every 4 warp wires, there is 1 sparse channel.
(13) When weaving special lightweight metal mesh, using a passive or semi-passive roll-up method will result in severe sparse and dense channels. Only by using an active limiting roll-up method can it be overcome.
Method to prevent thin and thick places in fabric: Due to the various reasons that cause thin and thick places in fabric, and the wide scope involved, it is necessary to put effort into multiple aspects in order to prevent them. It is crucial to improve the skill level of the weaving workers and enhance their ability to adjust and troubleshoot the loom.
