Determination of Wet Spun Flax Yarn Linear Density and Mechanical Properties
Wet spun flax linear density and mechanical properties depend on strict moisture regain control, hot water pectin drafting, and CRE tensile evaluation.
Mass Cv
Variation Coefficient
Statistical measures of the fluctuations in the weight per unit length of a yarn indicate the overall quality of the spinning process. The mass cv is the primary metric used to quantify the evenness of flax yarns as they are produced in the mill. It is calculated by dividing the standard deviation of the yarn mass by the mean mass and expressing it as a percentage.
Lower values signify a more uniform yarn with fewer thick and thin places.
Linear Density
Regularity in the distribution of flax fibres along the strand prevents the formation of weak points that could break during weaving. High mass cv values are often the result of poor fibre preparation or improper settings in the drafting zone of the spinning frame. These irregularities cause visual defects in the finished cloth, such as horizontal bars or a splotchy appearance.
Capacitance-based sensors on the winding machine track these variations in real-time.
Quality Grading
Spinning mills use this percentage to categorise their production into different quality tiers for the market. A yarn with a low mass cv is sold at a premium for use in high-density, fine-gauge fabrics. Conversely, yarns with higher variation might be relegated to rustic, coarse textiles where irregularities are seen as a design feature.
Precise control of this parameter is the mark of a sophisticated flax spinning operation.