Materials and Methods

The basic material used in the size-free weaving investigations was Acala cotton. The fiber was processed under almost mill-like conditions and spun into a 20/1 Ne (30-tex) rotor-spun yarn for both warp and filling. The yarn was warped on section beams and then beamed (assembled on a loom beam) by using different treatments on different sections of the warp. The beam was mounted on a modern high-speed, flexible-rapier weaving machine. Different reeds (viz. a conventional reed and a ceramic-coated reed), weaving speeds (varying from 250 ppm to 550 ppm), pick densities (varying from 20 ppi to 50+ ppi), and weaves (twill and plain) were investigated. A total of about 150 yards of mainly a twill fabric was produced. The Plain weaving had to be abandoned, since a weft density of even 40 ppi at 400 ppm presented difficulties. Thus, the initial weaving set-up consisted of producing a cotton twill fabric of a medium-light construction (63 x 40 ends and picks per inch, respectively) at 400 ppm. Additional weaving experiments were conducted with different weaving parameters to determine the effects of two most important weaving variables, namely, the fabric construction (cover factor/pick density) and the weaving speed, by independently varying and evaluating one variable at a time. Basically, the following is what we did to achieve what we did:

1)    Production of a cotton yarn of required structure, characteristics, quality and consistency, which would significantly contribute to attributes that are deemed desirable for size-free weaving.

2)    Development of technology to set the twist-torque or liveliness of warp yarn without traditional sizing.

3)    Modification of surface characteristics of critical components, mainly the reed, of the weaving machinery to minimize yarn abrasion and, consequently, reducing yarn breakages during size-free weaving and thereby improving weaving efficiency and fabric quality. A special ceramic-coated reed was investigated for its weaving performance

4)    Manipulation of weaving conditions and parameters, such as weaving speed, pick density, machinery settings, etc., to study their effects on the weaving performance and fabric quality. Dynamic tensions of single strands of the warp yarns were measured, using a yarn tension-cum-friction meter (See Figure 1). Hundreds of yarn and fabric photographs were captured in real time, using computer-aided techniques.

Figure 1. Single-End Dynamic Warp Tensions During Weaving