Weight Uniformity
Linear density deviation measures the consistency of the fiber weight per unit length along a strand of roving before it is spun. This characteristic, called roving mass variation, is recorded as a coefficient of variation percentage on a capacitive tester. Minimizing this variation is necessary to avoid spinning thin sections that break under twist tension.
Drafting Influence
High unevenness in the roving strand leads directly to thick and thin places in the final spun yarn. When a drafting frame encounters a thin section of roving, the reduction in fibers causes the draft to occur unevenly, producing a long thin area that cannot hold the spin twist. Conversely, heavy sections will fail to draft properly, resulting in large slubs that cause yarn breaks on the loom.
Spinning mills monitor roving mass variation using continuous capacitance measurements to detect wear in the gill pins or rollers of the drawing frames.
Quality Control
Limits for this variation are set in the spinner’s internal production recipes to ensure yarn consistency. Roving that exceeds the allowed coefficient is rejected or recycled to prevent high break rates on the ring frames. Tracking these levels helps maintain the target yarn count and strength.
