General Discussion on Fabric Structure and Analysis Part-1

General Discussion on Fabric Structure and Analysis

Bilal Yakubu
Dept. of Textile Science and Technology
Ahmadu Bello University, Zaria, Nigeria
Email: billsurf.net@gmail.com

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WARP RIBS
Ribs & Cords are plain weaves structures in which considerable difference exist between the warp & the weft threads as regards to thickness, & number of threads per unit space. The term cord is frequently applied to a rib that runs the length of the cloth. These designs are found in unbalanced structures such as canvases & tarpaulin.

This is a plain weave in which two or more picks are inserted in the same shade .To form warp rib the thick ends always passes over or under two or more , thick or fine pick as shown in figure 1 below & of 2-2 warp rib . Here the plain weave is extended for two picks. It is possible, however to have a 3-1-1-3 warp rib as shown in 2 below;

Fig 1: Warp rib

Fig 2: Warp rib

Warp rib weaves are made by running two or more picks together, a shown in Figure-3 This produces pronounced weft-way ribs, the surface of which consists of warp threads. The rib effect is emphasized by the use of a greater number of ends than picks and the insertion of coarser weft yarns. Consequently, the picks tend to lie rather straight with the ends bending round them, thus producing a warp rib structure in which the warp is mainly visible. The advantage of introducing two free weft yarns instead of one coarse yarn is that a broad rib is achieved without greatly increasing the thickness or weight of the cloth.

Since some confusion can arise in the terminology used, it is worthwhile drawing attention particularly to the fact that ‘warp rib’ weaves produce ribs running weft-way.

Rib effects result from extending the plain weave vertically. The weft is thicker causing the warp to bend and form a warp surface rib running from selvedge to selvedge.

• Warp ribs are woven with a high warp sett, in which the ends cover the weft almost entirely.
• The ribs can be emphasized even more strongly by use of alternate slack and tight ends and thick and fine picks.

Fig 3: Warp Rib Weaves

If the number of inserted picks in each shed opening is identical, warp rib will be designated as regular; in the opposite case, it is designated as irregular warp rib.

Regular warp rib weave:
The numbers of inserted picks in an even shed opening do not exceed 4. Thereby, only three regular warp ribs exist: warp rib 2-2, warp rib 3-3 and warp rib 4-4.

Regular warp rib weave

Irregular warp rib weave:
The irregular warp rib can be classified in three ways:

1. The varied warp rib where the number of picks in each shed opening varies periodically.
2. The interrupted warp rib, where grooves are separated by one, two or several picks to only one fine weft.
3. The varied interrupted warp rib that is the combination of the two preceding cases 

Irregular warp rib weave

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