3. Weaving

WEAVING

Weaving is one of the processes that required in textile in terms of producing a fabric. From the fiber then become a yarn through some other process, weaving is a process of interlacing two types of yarn known as warp or ends (run parallel to the weaving machine known as loom) and weft or filling yarn (run perpendicular to the loom) to produce a rigid fabric. [1]

Figure 1: Interlacement of warp and weft yarn

In order to interlace the warp and weft yarn, there are three operations which often called primary motions are necessary:

• Shedding- The process of separating the warp yarn into two layers by raising the harness to form an open area between two sets of warps and known as shed. [3]

Figure 2: Shedding process

• Picking- The process of inserting the filling yarn through the shed by the means of the shuttleless while the shed is opening. [3]

 Figure 3: Picking process

• Beating- The process of pushing the filling yarn into the already woven fabric at a point known as the fell and done by the reed. [3]

Figure 4: Beating process

To continue the weaving process, there are also two additional operations are essential:

• Warp control (let-off)- The motion that deliver warp yarn to the weaving area at the required rate and at suitable constant tension by unwinding it from the warp beam.
• Cloth control (take-up)- The motion that withdraws the fabric from the weaving area at the constant rate that will give the required pick-spacing and then winds it onto a roller. [3]

THE PRINCIPLES OF WEAVING PROCESS

Yarn Requirements:

Warp

• Yarns must be strong enough to withstand greater stress and abrasion during weaving.
• Yarn wound onto the warp beam from single packages
• Yarn strengthened and lubricated through sizing process
• Yarn smoothness increased through sizing materials
• Yarn elongation and flexibility must be sustained [2&3]

Weft

• Yarn must be wound properly on a suitable package for high speed unwinding.
• Yarn will be carried by shuttle that made up of wood which the pirn (hold the weft) is placed. [2&3]

Weaving preparations:

• Warping- A process of transfer the warp yarn from the single yarn packages to an even sheet of yarn representing hundreds of ends and then wound onto a warp beam. [3]

• Figure 5: Warping process
• Sizing/slashing- A process to give the strength to the yarn make it smoother and lubricate it (no effect on subsequent process or resulting fabric), also reduce the abrasion by give it through the section of the slasher. [3]

• Figure 6: Sizing process
• Draw-in- A process of draw every warp yarns through its dropper,  headle eyes and reed dent. [3]

• Figure 7: Draw-in process
• Tie-in- A process of tying each of a new beam to its corresponding end of the old beam when mass producing the same fabric. [3]

Loom Timing:

There are two types of loom timing in weaving process which are filament yarn timing and staple yarn timing. Loom timing is commonly in primary motions that involve in shedding, picking and beating process. It is sensible to make the period time of heald-shaft dwell coincide as nearly as possible with the passage of the shuttle. There are the timing period for each of the process done in the loom. The different between the two loom timing is the time of the dwell happen. The dwell is refer to the maximum opening of the shed in shedding process to let the weft inserted through it. [1]

Weaving Machine:

Weaving Machines (Loom):

Figure 8: Cross sectional of the weaving loom.

The cross sectional of weaving loom shows the main parts in the loom and the flow from the warp yarn inserting start from the weaver beam through weaving area and finally the fabric done wound onto the cloth roller.

Based on the cross sectional, some process in weaving are taking place such as shedding, picking and beating process. There are also let-off and take-up motions take place. [3]

The classification of the weaving machinery:

• Hand Looms : This kind of loom still used relatively large quantities for the production of all types of fabrics in the less-developed countries.
• Non-automatic Power Loom: These machines are being used in ever-decreasing numbers, especially in the developed countries, but they seem likely to retain a certain usefulness in the production of specialist fabrics.
• Conventional Automatic Loom: The machines that gained world-wide popularity because of their advantages of versatility and relative cheapness.
• Circular Loom: They are strictly limited in their applications, but they do achieve the ideal of high weft-insertion rates from relatively low shuttle speeds because insertion of the weft is continuous. [1]

Steps in the action of the insertion of warp and weft yarns in loom to form a fabric:

 Figure 9: Steps of inserting warp and weft yarn in weaving loom

1. The formation of shed by separating the warp yarns into two layers to create space to allow the shuttle to passing.
2. As the shed form, the shuttle carry the filling yarn is projected through it or we call as picking process.
3. Then, the beating take place to push the filling yarn to the woven fabric or fell.
4. The positions of the warp yarns are reversed to reform the shed and process is repeated with shuttle travels in the opposite direction. [2]

Conclusion:

                As the conclusion, weaving is a necessary process in fabric manufacturing. Weaving process known as the process of forming a rigid fabric by interlacing the warp and weft yarn. It also can produce a good end products with smoothness, less hairiness and strength characteristics of fabric because it has weaving preparation process. While learning weaving, we could know how the fabric produced and there are some weave structures that we can create. So, enjoying study this subject in you will know more about it and beside that exploring the textile world.