Quantifying Wet Spinning Limits for Low Cohesion Bast Fiber Slivers
Low cohesion flax slivers collapse under high draft ratios, requiring reduced trough temperatures, higher roving twist, and tight ratch settings to hold count.
Limit Count Nm
Yarn Estimation
Theoretical limit of yarn fineness that can be spun from a specific grade of flax fiber determines the technical limits of the spinning line. This value, designated as the limit count Nm, represents the highest metric yarn count that can be achieved before the yarn becomes too weak to spin without constant breakages. Fine linen yarns require fibers with low linear density and high length uniformity to support the yarn structure at these elevated counts.
Calculating this metric allows spinning mills to match raw material quality to the requirements of the final product.
Raw Characterization
Fiber properties such as average staple length, bundle strength, and clean fiber content are the primary determinants of the spinning boundary. For any given lot, the limit count Nm increases with the length and fineness of the flax fibers because a higher number of fibers can be incorporated into the yarn cross-section. Fiber alignment is essential.
When the raw material contains excessive short fibres or shives, the achievable count falls, forcing the mill to adjust the spun count downward to avoid excessive spinning waste and machine downtime.
Performance Variable
Spinning stability on wet frames depends on not exceeding this critical threshold of yarn thickness. When a mill attempts to spin a yarn count that exceeds the limit count Nm, the number of fibers in the yarn cross-section becomes insufficient to sustain the spinning tension, leading to frequent breakages and poor yarn uniformity.