Cotton Fiber Length Testing Methods and High Volume Instrument Span Metrics
HVI span metrics quantify cotton length through optical beard scanning, where 2.5 percent span length dictates drafting gauges and uniformity governs noil extraction.
Combing Noil
Fiber Waste
Extraction of short fibers and microscopic trash from textile slivers is a necessary step in producing high-quality combed yarns. The byproduct called combing noil consists of the shorter fibers that are rejected by the combing machine. This material is separated from the long fibers to ensure that the remaining sliver has high uniformity.
It is collected in large containers beneath the combing machine for reprocessing.
Extraction Mechanism
The combing machine uses a series of fine, revolving combs to treat the continuous cotton lap. As the comb needles pass through the fiber fringe, they catch and extract any fibers that do not reach the required minimum length. The machine then deposits these short fibers into a separate chamber while the longer fibers are consolidated into a high-quality combed sliver.
Adjusting the comb settings allows the operator to control the percentage of extracted material.
Yarn Uniformity
Removing these shorter fibers drastically improves the strength and appearance of the final yarn. Combed sliver with low remaining short fiber content produces yarns that have fewer defects and greater uniformity. These yarns are ideal for high-speed knitting and weaving, where yarn breakages must be kept to a minimum.
Economic Recovery
Although the extracted fibers are too short for high-grade apparel, they have significant commercial value in secondary markets. Nonwoven manufacturers purchase this material to produce cotton pads and wipes. It is also used in the paper industry and for manufacturing coarse utility yarns.