UNIT Ⅱ Compound Structure Chapter 6 Backed weaves Chapter 7 Multi-ply Fabrics Chapter 8 Pile Fabrics Chapter 9 Gauze and Leno weaves Chapter 10 Jacquard Fabrics

Introduction: Fundamental and combined weaves are considered to be simple, though there are a great variety of types and constructions. In these weaves, only one system of warp threads are interlaced with one system of weft threads at right angles. Due to this, the methods of construction of these weaves and production of fabrics of such weaves at textile mills are quite simple.

Compound weave fabrics are of a specific structure, therefore special methods and mechanisms should be used in their production. For instance: 1) blanket made from backed weaves; 2) many industrial fabric made from multi-layer weaves; 3) terry fabric made by a special mechanism; 4) pile fabrics made by a special finishing process; 5) leno weave with open structure made by using a special heald.

Chapter Six: Backed weaves The principle of backing a cloth with a second series of either weft or warp threads is to add extra weight and warmth without interfering with the smooth surface of the fabric. The end uses of backed cloths range from apparel to home furnishing.

6.1 Warp backed weaves I Concept: These are weaves which have two systems of warp and one system of weft. The face weave is formed by interlacing face warp and weft, and the back weave is formed by interlacing back warp and weft. The system of weft plays an important role due to interlacing with both systems of warp. The weft threads are raised above the face warp and lowered the back warp.

II Construction of warp backed weaves 1) Selection of face weave and back weave The face weave can be same as the back weave, and can be different from the back weave, but the face weave should be warp-faced weave such as 3/1 twill, back weave should be weft-faced weave such as 1/3 twill. 2) Selection of the starting point in construction of a back weave:

3) Determine the ratio of the face and back warp: In order to get a better appearance of the fabric, the backing stitches (back warp floats) should be hidden between floats on the face. 3) Determine the ratio of the face and back warp: Usually the ratio is: m : n = 1:1 or m : n = 2:1.

4) Calculate the “new repeats” 5) Transfer the weaves Transfer the face weave and back weave into one weave.

Example: Construct a backed weave: face weave : 3/1↗ back weave : 1/3↗ warp ratio: 1:1 1) Selection of face weave and back weave: both weaves have been given

2) Determine the starting point: Should meet the previous point 2, stitching float should be covered by face warp float. 3) Determine the arrangement of the face and back warp: Warp ratio: 1:1

4) Calculate the repeats and outline the repeats: The outline is drawn as :

5) Transfer the weaves face cross-section longitudinal section back ③ ① ④ cross-section ② 1 longitudinal section Ⅰ Ⅲ Ⅱ Ⅳ back ④ ③ face ② back ① 1 Ⅰ Where: × indicates intersections of face warp and weft threads and ■ indicates that of back warp and weft threads. 1,2,3 and 4 are face warp threads while Ⅰ,Ⅱ,Ⅲ and Ⅳ are back warp threads.

Ⅲ Applications It is widely used for making woolen and worsted fabrics. Notes: Face ends are usually drawn into the front shafts.

6.2 Backed weft weaves I Concept: These are weaves which have two systems of picks and one system of ends. The face weave is formed by interlacing warp and face weft threads. While the back is formed by interlacing warp and back weft. Weft faced structures are more suitable for this method as the backing stitches can be hidden between floats on the face.

II Construction of weft backed weaves The principles of the construction of backed weft weaves are similar to warp backed weaves. 1) Selection of face weave and back weave The face weave can be same as the back, and can differ from that, but the face weave should be weft-faced weave such as 1/3 twill, back weave should be warp-faced weave such as 3/1 twill.

2) Determine the stitching distribution The correct stitching plays a very important role in the construction. On no account must it be visible on the face of the fabric. 3) Determine the arrangement of the face and back picks. m : n =1:1 or m : n = 2:1. 4) Calculate the new repeats 5) Transfer the weaves

Example: Construct a weft backed weave, ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ face weave: 1/3 Z twill; back weave: 3/1 Z twill ;warp ratio--1:1 A: Calculate the new repeats: Ry= LCM of =4×2=8 RO=LCM Rm & Rn=4 ■ ■ ■ ■ B: Indicate the face warp floats with ■ on the face ends 1,2,3 and 4. ■ ■ ■ ■ ■ ■ ■ C: Complete the back warp floats with ■ on the corresponsive ends ■ ■ ■ ■ ■ Weft backed weave

Ⅲ Applications It is widely used for blanket and woolen fabrics.

Home works 1. Construct backed warp weaves: (1) Face weave 3/1↗, back weave 1/3↗, arrangement of face warp and back warp m : n=1 : 1 (2) face weave 8/5 satin, back weave 1/3↗, m : n=1 : 1. 2. Construct backed weft weaves and their cross-section diagrams. (1) face weave 1/3 broken twill, back weave 3/1 broken twill, m : n=1 : 1. (2) face weave 2/2↗, back weave 3/1↗, m : n=1 : 1.