SUBJECT: STRUCTURAL FABRIC DESIGN

TOPIC: TERRY PILE STRUCTURE

The terry pile is a class of warp pile structure in which certain warp ends are made to form loops on the surface of the fabric. The loops may be formed on one side only or on both sides of the fabric thus producing single-sided and double-sided structures as shown in Fig. 1 & 2 respectively. A high tension is applied to a ground warp and a very low tension to a pile warp. In traditional terry weaving, by means of a special device on the weaving machine, two picks are inserted at a variable distance ‘‘the loose pick distance’’ from the fabric fell. the two picks are beaten up short of the true fabric fell and produce a temporary false fell as indicated schematically in Fig.1 A and B. The loose pick distance is varied according to the desired loop height. On the third pick of the group full beat-up takes place the three picks being pushed forward together to the true fell position. During this action the three picks are capable of sliding between the ground ends, which are kept very taut, as depicted in Fig. 1 C, D and E.

A. 1st. temporary false fell B. 2nd temporary false fell C. 3rd pick of the group D. Whole group is pushed into the fell point E. Full beat-up

Fig. 1: Phases of the pile formation on terry weaving machine

It can be therefore determined some principles: 1. The smallest wefts group is three wefts. 2. The pile yarns must be always intersected with the second weft of the wefts group. 3. The warp shedding must be closed during beating-up of the third pick The exact relation of the weft to the two warps and the principle of loop formation is depicted by means of the weft section in Fig. 2. The broken vertical lines CC, DD, and EE divide the first, second and third picks into repeating groups of three, line EE indicating the position of the fell of the fabric. On the right of the diagram, a group of three picks, which compose a repeat, is represented previous to being beaten up to the fell of the fabric. The ground threads G1, G2 , and the face and back pile threads P1 and P2 are shown connected by lines with the respective spaces in the corresponding weave given in Fig. 2. In weaving the fabric the group warp beam carrying the threads G1 and G2, is heavily tensioned. As stated earlier so that these threads are held tight all the time. The picks 16 and 17 are first woven into the proper sheds, but are not beaten fully up to the fell of the fabric at the time of insertion in their sheds; but when the pick No. 18 is inserted the mechanisms are so operated that the three picks are driven together into the fabric at the fell EE. During the beating up of the third pick the pilewarp threads P1 and P2 are either given in slack, or are placed under very slight tension.

Fig. 2: Structure of three-pick terry, pile on both sides

The picks 16 and 17 are in the same shed made by the tight ground threads G1 and G2, which, therefore, offer no obstruction to the two picks being driven toward at the same time with the third pick. The pile threads P1 and P2, on the other hand, change from one side of the fabric to the other between the picks 16 and 17, and they are, therefore, gripped at the point of contact with the two picks. As the three picks are beaten up this point of contact is moved forward to the fell of the fabric with the result that the slack pile warp threads are drawn forward and two horizontal rows of loops are formed one projecting from the upper and the other from the lower surface of the fabric in the manner represented in Fig. 3. Setting of shedding level of the pile and ground shafts is shown in Fig. 2.15.

Fig.3: Diagram of three-pick terry design, pile on both sides.

Fig. 4: Setting of shedding level of the pile and ground shafts

Main methods for the production of terry fabrics The production of terry fabrics is a complex process and is only possible on specially equipped weaving machines. Terry weaving machines are constructed so as to impart a loop to warp yarns via weft yarns which are beaten up at a beating-up station to form a fabric. Two warps are processed simultaneously, the ground warp, with tightly tensioned ends and the pile warp, with lightly tensioned ends. In general, the reed has two beat-up positions which do not impose alternative movements to the warp, fabric and various components of the weaving machine. Special weaving methods enable loops to be performed with the lightly tensioned warp ends on the fabric surface. Those methods are divided into two mains methods as follows: • Reed control mechanism • Fabric control mechanism.

Formation of warp pile fabrics on face to face principle:

Face-to-face weaving represents an alternative method of manufacture of the cut warp fabrics in which two fabrics are woven simultaneously and the pile is produced without the aid of wires. Two separate ground fabrics with a space between them, each with its own warp and weft, are woven on the unstitched double fabric principle, while the pile warp threads interlace alternately with the picks of both fabrics and thus are common to both. The distance between the ground fabrics is regulated according to the required length of pile and as the textures pass forward the pile threads extending between them are cut by means of a transversely reciprocating knife during the weaving process. Upper fabric is thus formed the lower fabric with the pile facing up, and the upper fabric with a similar pile facing down. The fabrics pass in contact with separate take-up rollers and are wound on two fabrics. Fig.1 illustrates double-layer fabrics produced on the face-to-face principle

Tapestry:

Tapestry is a form of textile art, traditionally woven on a vertical loom. Tapestry is weft-faced weaving, in which all the warp threads are hidden in the completed work, unlike cloth weaving where both the warp and the weft threads may be visible. In tapestry weaving, weft yarns are typically discontinuous; the artisan interlaces each coloured weft back and forth in its own small pattern area. It is a plain weft-faced weave having weft threads of different colours worked over portions of the warp to form the design.[1][2] Most weavers use a natural warp thread, such as linen or cotton. The weft threads are usually wool or cotton, but may include silk, gold, silver, or other alternatives.