Yarn: mass measurement with 1-mm length samples

Abstract

In textile production, measurement of yarn mass in the 1-mm range is of utmost importance to properly evaluate evenness, as several irregularities occur in 1—4-mm yarn Iength. Direct measurements in the 1-mm range are not available in commercial equipment. One of the most common, from Uster, is based on yarn samples of 8 mm. This paper presents a direct mass measurement in the 1-mm range system based on parallel capacitive sensors and signal-processing techniques for detection of periodical errors. Results point out that evaluation of yarn mass, with this approach, is feasible in the 1-mm range, allowing online measurement (1-mm yarn mass) in a spinning frame for real-time control. Despite low signal-to-noise ratio, it is possible to measure small variations of yarn mass (typical capacity variation of 2.08 x 10-17 F for 57 tex—O.057 g/m of yarn). As a spin-off of this project, a new low-cost control system is being prepared for detection of yarn break and bobbin end in knitting flat machines. Online quality classification is also feasible with the developed system.