8.2 Warp Pile Introduction: 1: Method of weaving 2: Cutting (arrows) 3: Development of pile weaves

Introduction: Warp pile fabric contains three systems of warp and two systems of weft: face end, back end and pile end; face pick and back pick, where face weave and back weave are called ground weave. See Fig. 8.6: Fig. 8.6

The face and back fabrics are stitched on the loom by means of pile warp. The two fabrics are separated by cutting the pile threads. From Fig. 8.6 we can see a clear difference in warp crimp between ground weave and pile warp, so a separate weaver’s beam is necessary in weaving warp pile. The representative fabric of warp pile is velvet.

1. Method of weaving Two ground cloths are produced with a certain space between them. The distance from face to back fabric determines the required height of the pile. Pile ends interlace alternately with face and back picks. According to different shedding and picking during the weaving, two categories are classified as following : A Fig. 8.7 sketch of warp pile weaving B

1. Single shedding. See Fig. 8.7 (A) (show flash) Face cloth is formed by face ends and picks, Back cloth is formed by back ends and picks 2. Double shedding. See Fig. 8.7 (B) (show flash) Face and back cloths are formed simultaneously, identically interlacing ends are drawn into two mail healds. Face and back picks are inserted in pairs.

2. Cutting (arrows) The two fabrics are separated by cutting the pile threads in the middle during the weaving process. Cutting takes place when the race is put back and the pile ends are taut. Each cloth is to be wound on separately. F = face B = back P = pile

3. Development of pile weaves 1) Selection of the ground weave. For velvet, 1/1 plain is preferable. Sometimes, 2/2 weft rib and 2/1 varied rib are selected. The density of the piles, distribution of the piles need to be considered during selection. 2) Determine the ways of binding type. V-type is preferable compared with W-type. 3) Determine the ratio of the ground and pile warp 4) A section diagram is helpful to the weave construction.

Example 1: Construct the warp pile weave, the parameters are given below: V type binding Warp: 1 pile end―1 face―1 back―1 pile―1 face―1 back end Weft: 1 face―1 back pick. Ground: plain weave for face and back weaves.

Answer to example 1: ■ ■ ／ ／ × × ／ ★ ■ Determine the repeats and draw the outline ★ ／ × ／ ★ ■ ★ Draw the longitudinal-section Transfer the weave

Notes to the key: In the figure: a, b --- pile ends Final weave:

Example 2: get familiar with the following warp piles: V-type structure, one pile system Warp: 1 pile ---- 1 face end ---- 1 back ---- 1 face ---- 1 back end for ground Weft: 1 face pick ---- 1 back pick Ground : plain weave for both face and back cloths Pile: interlaces alternately with face and back picks

Fast or W pile binding, one pile system Warp : 1 pile end ---- 1 face --- 1 back --- 1 face --- 1 back end for ground Weft : 3 face picks --- 3 back picks Ground : rib for face and back cloth Pile :interlaces alternately with 3 face and 3 back picks.

V-type binding, two pile systems Warp: 1 face end A ---- 1 face ---- 1 back end 1 pile end B ----1 face ---- 1 back end Weft : 1 face ---- 1 back pick Ground : plain weave for both face and back cloth Pile: both pile ends interlace alternately with face and back picks

Applications: Warp pile fabrics possess full piles. Soft hand, good elastic recovery, good crease resistance, thermal insulation and delicate colour. Widely used for lady and children cloth, drapery, seats covers, package cloth for some valuables.

Home works: According to the longitudinal-sections, indicate the required parameters and draw the weaves. 1)binding types; 2) arrangement; 3) ground weaves; 4) weaves Ⅰ Ⅱ Ⅲ

8.3 Terry pile Introduction: These fabrics of such weaves are characterized by formation of loops which are raised above the surface of the fabric either on one or both sides. The fabrics possess a relatively high level of wet ability, hygroscopic, and soft handle. They are used for toweling as well as for bath mats, bed covers and dress.

The principles of loops formation (show flash) 1. Special beating up – Terry pile motion . “short beating” and “fast beating” 2. Special warp threads The ground warp has a higher tension; and the pile warp have a loose tension.

3. Special weaves and coordination Resistance of the beating-up should be minimum. The pile warp is firmly held by ground weave. After last beating-up, the last weft can not move reversely.

Fig. 8.9 Analysis of three picks terry pile

First ,resistance of the beating-up: See Fig. 8.9 (A), (B), (C). At (A), the ground ends interlace with weft two times; and at (B), (C) one time. So weave (A) has a bigger resistance than (B) and (C). (B), (C) are preferable. Second, holding force: (B), (C) have same gripping force to the pile warp. At (C), weft 1 and 2, hold the pile warp; at (B) weft 2, 3 hold the pile warp. At (B), the loops can not be evenness. (C) is the best . Third, reverse motion of the last pick: At the diagram (A) the weft 3 and next repeat weft 1 are in the same fell. So after the reed goes back, the pick 3 will be moved reversely.

At diagram (B), pick 3 can be moved, but it is not serious At diagram (B), pick 3 can be moved, but it is not serious. The loop would change as the pick removes. At diagram (C), even the pick 3 can be removed, but the gripping force come from weft 1, 2, so it will not affect the pile loop and the loop are kept constantly. According to the analysis above, (C) is the best weave for 3-picks terry fabric.

Example 1: single sided pile (B) ( C) Fig.8.10 single sided terry pile Longitudinal-section

Example 2: double sided pile (A) (B) (C) Double sided terry pile Longitudinal-section

Homework: Describe the principles of terry pile formation. Main points: (1) fast beating and short beating. (2) loose tension warp, higher tension warp. (3) Weave possess three requirements.