Yarn is employed worldwide for creating a good range of textiles and apparel. Its structure and appearance have signiﬁcant inﬂuence on the properties and performance of the yarn and its end-products. Therefore, the analysis of yarn structure and appearance is a crucial need and procedure. In assessing yarn quality within the textile industry.
Yarn Structure and Appearance
Traditionally yarn structure and appearance are evaluated subjectively by manual methods. But a number of the methods are subjective. Less reliable and labor intensive. With the rapid development of technology , efﬁcient and low-cost techniques are established. For the accurate image acquisition and large image storage.
At an equivalent time, image processing, computer vision and pattern recognition have achieved their respective high levels of progress. Those developments in digital technology bring new data acquisition apparatus. New data analysis and recognition approaches. Thus providing an alternate objective method for yarn feature analysis. A generic diagram of digitalized yarn feature analysis. We’ll present the state-of-the-art digital technologies for yarn structure and appearance analysis.
More speciﬁcally, we glance into the newest developments in yarn evenness measurement, yarn hairiness analysis. The Yarn twist and snarl measurements, yarn blend analysis and yarn surface appearance grading . Afterwards, we’ll discuss the longer term trend of this area in Section 1.8. Concluding remarks are drawn.
Measurement of yarn evenness Consistent yarn thickness is important for the top quality of textile products. For several years, yarn irregularity has been measured. By the capacitance evenness tester using two parallel capacitive sensors. The capacitance based method is accurate and stable in yarn mass measurement and has been well accepted within the textile industry for many years .
Yarn Irregularity – Textiles and Apparel
Nevertheless this method can only provides a rough description of yarn irregularity in diameter. Optical measurement alternatively provides a more accurate method in determining. The yarn diameter and its variation by using optical sensors. because the diameter of a yarn is measured. The optical based method isn’t suffering from moisture content or ﬁber blend variations within the yarn.
The Uster evenness tester and therefore the Zweigle G580 are two representative instruments commercially utilized. In the textile industry for the capacitive and optical measurements of yarn evenness as well as respectively. Recent developments in capacitive and optical measurements. Along side the digital signal processing of study , make the yarn evenness results more practical and sensible. As an example , Rong and Slater (1995) developed a microcomputer system using digital signal processing for yarn unevenness analysis. during this system.
The Uster Tester
The analogue signal of the diameters of one yarn, measured by the Uster Tester. It was converted into a digital form then further analyzed by means of frequency spectroscopy techniques. Additionally to the normal statistical parameters for characterizing irregularity, yarn unevenness might be assessed by using the probability density function, which was known to be closely correlated with fabric appearance quality. Supported the capacitive principle, Carvalho et al. In 2006 also developed a replacement system for accurate yarn thickness and evenness measurement by using capacitive sensors and digital signal processing techniques. As compared to commercial instruments. This technique enabled direct measurement of yarn mass as well as with a high resolution of 1 mm in yarn length in textiles and apparel.
With the accurate measurements of yarn mass, some signal processing algorithms. Like FFT (Fast Fourier Transform) and FWHT (Fast Walsh–Hadamard Transform). There were employed to detect a good range of yarn faults in lengths of 1 mm and above. In optical measurement as well as an optical signal processing system has been developed (Carvalho et al., 2008) to live yarn diameter. As shown in a helium neon (HeNe) laser was wont to emit a coherent light which