In the entire process of gray fabric production, the selvedge plays an extremely important role. During the weaving process, the edges of the fabric must be fastened to both ends of the weft yarns to withstand the strong force of the temple braces, so that the fabric surface does not produce excessive weft shrinkage, reduce the bending of the edge warp yarns, improve the friction between the edge warp yarns and the reed teeth, and reduce the friction between the edge warp yarns and the reed teeth. The edge warp yarn breakage rate increases the edge strength, keeps the cloth surface flat and consistent in width, and is easy to wind and form well, which facilitates subsequent processing.
During the dyeing and finishing process, the edge of the fabric is also subject to tension from cloth clips or needle punching. Especially cellulose fiber fabrics such as cotton and linen have to withstand a lot of tension during the setting and tentering process after mercerization. Therefore, a strong, flat, and appropriately tight edge structure is a necessary condition for finishing. Unreasonable fabric edge design will cause the fabric to have loose edges, broken edges, tight edges, curled edges, etc. In severe cases, a large number of broken edges will occur, and even post-finishing processing will be impossible, causing huge losses.
In shuttle looms, the weft yarn is alternately inserted on both sides through the shuttle to form a smooth edge; while in rapier looms and air-jet looms, the weft yarn is unwound at high speed through the package, and the weft yarn is inserted in one direction, and both sides of the weft yarn are free end, and then form a burr. In the middle part of the fabric, the weft yarns have a greater degree of buckling and are relatively uniform, while the two sides of the fabric are free ends and are mainly held by the seams and false edges. If the edge design is unreasonable, the tension of the weft yarns at the edges will be greater than that of the fabric body. The weft yarn tension is much smaller and the weft yarn is loose, which will cause weft shrinkage, and the weaving shrinkage rate of the warp yarns at the edge and the warp yarn of the cloth body will be quite different, which will bring hidden dangers to the subsequent processes.
Twill and forged weaves generally use borrowed edges, that is, a single heddle and a ground weave are woven together. The pattern plates must be opposite, for example, 4/1 edge and 1/4 of the ground weave, with opposite weave points, jacquard weave, and joint weave. Once you are used to using heavy flattening and square flattening to make edges, consider the following four aspects:
1) Width
If the edge tissue is too narrow and not strong enough, it cannot withstand the tensile force. It is easy to tear the edge and cannot be lifted. protective effect. If it is too wide, it increases the cost of the fabric and affects the cutting area of the fabric under a certain width. Generally speaking, a simple weave fabric only needs a smaller width, but the width of the selvedge of some same-face, different-face weaves and stretch fabrics with longer floating lines should be appropriately increased according to the situation.
2) Thickness
The thickness of the edge should be as consistent as possible with the body of the fabric, so that it is easy to keep the fabric flat, winding, beautiful, and evenly stressed.
3) Tightness
The edge of the fabric is usually slightly tighter than the body of the fabric, but it must not be too tight. Too tight will affect the finishing, because the edge of the fabric cannot withstand large deformation in a short period of time, and may even tear the edge of the fabric, making the entire batch of fabrics useless. It won’t work if it’s too loose. On the one hand, it will cause weft shrinkage and ruffles, which will easily break during finishing. Therefore, the density of edge tissue is greater than that of ground tissue.
4) Drawing-in and reeding
The number of healds used for the edge should be as small as possible, so that the heald frames can be easily organized to make edges. Usually two more pages of healds are added, otherwise it will increase the difficulty and cost of weaving. Reeding is mainly designed based on the organizational structure of the edge and its required functions to meet the requirements of the edge.and function, the number of reeds for the edge weave is usually not less than the number of reeds for the ground weave. For varieties with more than 8 pages, it is best to place the edges on the first two pages to ensure clear edge openings and reduce the number of weft stops.
5) It is recommended to make 4/1 elastic fabric. If using a dobby machine, it is recommended to use 2/2 square. For stability, it is recommended to use 2/3+3/2 single wear when using a pedal. Compared with 1/4+4/1 is not easy to curl. You can also “add keel ribs” in the 2/3+3/2 selvage, which is also helpful to overcome the curling caused by the large difference in the longitude and latitude tissue points of the two sides.
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