Quantifying Carding Waste Composition Drift in Cotton Synthetic Blends
Carding waste selectively extracts short cotton over synthetic staple, shifting sliver ratios by up to 2 percent synthetic enrichment unless compensated in laydown.
Short Fibre Index Extraction
Process Optimization
Elimination of immature and broken fibres from the cotton stock during carding or combing reduces the risk of yarn defects in subsequent processing steps. This selective removal, called short fibre index extraction, improves the average length and uniformity of the remaining fibre bundle. It is measured by comparing the fiber length distribution before and after processing.
The action directly affects the yarn spinning limit.
Mechanical Operation
Combing machines achieve this separation by passing the fibre fringe through a fine circular comb that traps and removes short fibres. The mechanical settings for short fibre index extraction are adjusted by altering the feed distance and the timing of the nipper frame. A wider setting increases the amount of noil extracted, which removes more short fibres.
This mechanical process is monitored by measuring the noil percentage.
Yarn Performance
Reducing the short fibre content is necessary because short fibres do not spin securely into the yarn core, leading to high hairiness and low tensile strength. When short fibre index extraction is neglected, the resulting yarn has more neps and experiences more breakages during winding and knitting. These breakages stop high-speed looms, which increases the production cost of the fabric.
High-quality fine counts, such as those used for luxury bed sheets, require a very low short fibre index, which demands thorough combing. By optimizing extraction, mills ensure that the yarn meets the physical requirements of demanding apparel brands.
Laboratory Validation
Laboratories use high-volume instruments or photoelectric testers to measure the change in the short fibre index of the sliver. These tests verify that the process is operating within the specifications agreed upon in the purchase contract.