Yarn Preparation for Weaving and Knitting

Study Notes

The main purpose of yarn preparation is to improve the yarn's ability to be woven or knitted efficiently.
The quality of yarn affects the speed of weaving or knitting and the quality of the final fabric.

To improve efficiency, yarn breakage must be reduced to a minimum.
This can be achieved by: winding onto a suitable package, clearing yarn of defects, and treating the yarn before use.

Winding transfers yarn from the spinner's package to another package suitable for its end use.
The end use could be for weft, dyeing or creeling of a warping machine.
For efficient warping, long continuous lengths of yarn are required, typically over 50,000 meters.
Yarn from multiple spinner packages is wound onto a larger package called a cone or a cheese.
The package's size, shape, and build are chosen for maximum efficiency in the next process.
Yarn must be wound in a way that allows for easy unwinding, good stability, and high-speed operation.

The process of removing faults from yarn is called yarn clearing.
Thick and thin places in the yarn are eliminated during this stage.
Yarn winding machines are equipped with electronic yarn clearing devices.
The clearing limit of an electronic yarn clearer determines the threshold level for yarn faults.
If a fault exceeds the clearing limit, the cutter is activated to remove the fault.
The clearing limit consists of two settings: sensitivity, which determines the activation limit for the fault's cross-sectional size; and reference length, which defines the length of yarn over which the cross-section is measured.

Yarn ends are joined together by splicing to ensure continuity in the wound package.
Splicing replaces serious faults with less serious ones.
Splicing is a technique that joins two yarn ends knot-free by intermingling the fibers.
Splicing is performed by untwisting and re-twisting the yarn ends using an air blast.
First, the yarn is opened and the fibers are intermingled.
Then, yarn is twisted in the same direction as the parent yarn.
The effectiveness of splicing depends on the tensile strength and physical appearance of the joint.

Yarns are waxed or lubricated to improve their slide performance during knitting.
Staple yarns are usually waxed, while filament yarns are lubricated.
This treatment changes the surface frictional properties of the yarn, resulting in a lower coefficient of yarn friction.
Lowering the friction coefficient improves knitability.
Waxing reduces the friction between the yarn and the knitting needles.
Waxing also provides anti-static characteristics to the yarn.

Yarn preparation involves processes that improve the yarn's ability to be woven or knitted efficiently.
Winding, yarn clearing, splicing, and lubrication/waxing are essential steps in yarn preparation.
These processes ensure a higher quality fabric with less breakage and improved efficiency in weaving or knitting processes.