Summary of yarn number and test

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University of North Carolina, Chapel Hill *

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220

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Industrial Engineering

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Oct 30, 2023

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docx

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Summary of yarn size and testing 1. Types of yarn -Spun yarns (ring, rotor, air jet, or air vortex) -Filament yarns -Plied yarns -Specialty yarns 2. Fiber and yarn numbering system -Need a system to quantify the size of fibers and yarns. -While it would be useful to have a direct measure of yarn and fiber diameter this requires specialist equipment and would take lots of time to sample and measure. -Additional problem is that many fibers and yarns are not circular plus spun yarns are easily compressed and deformed so that mechanical measurement approaches are not generally adopted. 3. Direct system 4. Indirect system -Cotton hanks/lb (1 cotton hank = 840 yds) -Worsted hanks/lb (1 worsted hank = 560 yds) -Woolen run hanks/lb (1 woolen run hank = 1600 yds) -Meters/gram (Metric count) 5. Number of fibers in a yarn 6. Plying and cabling -Plying is the process of twisting two or more single yarns. -Cabling is the process of twisting two or more plied yarns.

7. Special designations 8. Yarn test -Yarn Count -Yarn Tensile Properties -Yarn Evenness -Yarn Hairiness -Yarn Twist 9. Tensile properties – USTER® TENSORAPID 5 – universal tensile tester for globally accepted standards in both staple and filament yarns. Testing speed is steplessly adjustable between 50 and 5000 mm/min. – USTER® TENSOJET 5 – for precise forecasting of yarn processability for high speed weaving machines, with a test speed of 400 m/min. 10. Evenness -Evenness is characterized by the variation in weight per unit length of a sliver, roving, or yarn. -The more uniform (even) the sliver, roving, or yarn, the better quality of the end product. -A coefficient of variation (CV) is used to describe the change in thickness of a particular

sliver, roving, or yarn. -The CV% is an indication of how widely distributed the independent data is with respect to the average. -Two methods to measure evenness: capacitance, optical 11. Hairiness -The fiber ends often protrude from the yarn surface causing hairiness. -Shorter fibers result in a larger number of fiber ends (for a given mass of fiber) and thus a hairier yarn. -Hairiness is not only fiber ends, it comprises wild fibers, looped fibers. -Hairs under 3 mm in length actually make the fabric feel softer and luxurious. -There is a great effect of spindle or rotor position (the individual yarn production units) on yarn hairiness, particularly in ring spinning. -Winding (a process in ring spinning where small packages from the spinning machine are combined into larger packages) has a great effect on yarn hairiness in ring spinning. -Two methods to measure yarn hairiness: light scattering, photocells

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