The fiber stream is a term often used in technological spinning processes. It denotes a certain arrangement of fibers, characterized by varying degrees of ordering, parallelization (straightening and parallel arrangement of fibers), evenness of the linear mass, and blending. The fiber stream can represent, for example, spinning intermediate products such as sliver or roving, but yarn is also a fiber stream. With respect to the quality of flat textile products, the evenness of fiber distribution over the length of the stream is the most important quality parameter of yarns.
Analysis of the distribution of fibers in the yarn, i.e., the assessment of irregularity of the linear mass of the fiber stream, should take into account certain universal principles. First of all, it is assumed that a properly conducted spinning process is stationary in character. This means that the test results do not depend on the choice of the zero point of measurement on the length of the fiber stream, and thus, the starting moment of the measurement can be freely selected.
Three types of analysis are commonly used to assess the unevenness of the linear mass distribution of the fiber stream:
harmonic analysis of the distribution of linear mass over the fiber stream analysis of the distribution of linear mass in the fiber stream by the moving average method correlation analysis of the linear mass distribution of the fiber stream.
harmonic analysis of the distribution of linear mass over the fiber stream
analysis of the distribution of linear mass in the fiber stream by the moving average method
correlation analysis of the linear mass distribution of the fiber stream.
The most commonly used method is harmonic analysis due to the commonly used equipment, which facilitates and significantly accelerates such analysis and, most importantly, eliminates subjective assessment.
An ideal fiber stream is a collection of straight fibers, arranged in parallel along a straight line according to a certain conventional statistical scheme. This is a special case of a real fiber stream, possible to obtain under ideal technological conditions. Only an ideal model of a stream composed of fibers differing in length and linear mass, but of constant thickness along their axis, can be of practical importance. The variance
This determines the basic property of a quantity subject to Poisson distribution. Hence, the coefficient of variation
Since it has been assumed that the fibers have the same linear masses, the coefficient of variation of the linear mass (thickness) of the stream is equal to the coefficient of variation of the number of fibers
Taking into account the fact that under real conditions the fibers have not only different lengths but also different linear masses (thicknesses), the unevenness of the ideal fiber stream
The K = 1.02 for chemical fibers, K = 1.06 for cotton fibers, K = 1.12 for wool fibers, K = 1.26 for flax fibers.
K = 1.02 for chemical fibers,
K = 1.06 for cotton fibers,
K = 1.12 for wool fibers,
K = 1.26 for flax fibers.
For a multicomponent blend, the variance of the total cross section of the fiber stream will be equal to the sum of the variances of the component streams. In this case, the irregularity of the ideal fiber stream
The ideal stream provides the standard for real streams. The relationship between the ideal and the actual stream is illustrated by the Huberty index (the so-called index of irregularity):
For the ideal process, the Huberty index
The values of the Huberty index depend on the technological process and the type of processed fibers, and for exemplary yarns they are as follows :
- for carded cotton yarn
1.8 ÷ 2.6
- for combed cotton yarn
1.3 ÷ 1.6
- for yarns of man-made staple fibers
1.5 ÷ 2.2
- for worsted woolen yarn
1.1 ÷ 1.4
- for carded woolen yarn
1.4 ÷ 2.1.
During the technological process, along with the consecutive phases of yarn production, the Huberty index is reduced asymptotically, which is illustrated by the example of Figure 1.
The Huberty index is the greatest for the disordered fiber structure (phase 0) at the beginning of the technological process. In each subsequent phase of fiber processing, this coefficient should be lower, as a result of fewer and fewer fibers in the stream cross section and better and better parallelization of fibers. The disruption of this trend, as illustrated in Figure 1 in the third phase of spinning (dashed line), suggests irregularities in the technological process (in phase 3), which will certainly have a negative impact on the quality of the yarn.
The fiber stream traveling through any spinning machine comes into contact with many working elements, which for the most part are of a rotating nature (working rollers, cylinders, spindles, rotors, etc.). Any possible defect of such elements (e.g., damaged cover of the upper rollers of the drawing apparatus) causes interference in the fiber stream. Such disturbances are periodic, i.e., repeated regularly at the intervals equal to the circumference of the damaged rotating element. Even if the irregularity appears in the fiber stream leaving the machine at any stage of the technological process, it is very difficult to remove in the subsequent phases of processing. The error goes to the yarn, the quality of which is thus reduced [8, 14]. The disturbance in the fiber stream is usually so small that it is impossible to observe without specialized equipment. It becomes apparent only during the production of flat textile products in the form of weft or warp stripes in fabrics, or strippedness caused by uneven meshes in knitted fabrics. The process of finishing such a product, e.g., by dyeing, makes the resultant irregularities even more visible .
Figure 2 presents the scheme of creating stripes in fabrics due to periodic irregularity of the yarn linear mass distribution (periodic thickening).
The periodic irregularity of the yarn linear mass distribution is not always visible in flat textile products in the form of stripes [6,9,11]. It can manifest, e.g., as the “moiré” effect (Figure 3), irregularities visible when winding yarn on a contrast plate (Figure 4), or a simulation of the appearance of the fabric or knit after yarn analysis on the Uster testing device (Figure 5).
The Uster Tester, among others, is used to analyze the mass distribution in the fiber stream. The measurement is performed between the covers of the capacitor, in which changes in capacitance occur under the influence of momentary changes in the linear mass of the sliding fiber stream. Such instantaneous changes in the capacitor capacitance are proportional to the instantaneous changes in the thickness of the fiber stream and are mapped in the form of a mass diagram. On the basis of the obtained results, the Uster device performs harmonic analysis, i.e., it breaks down the mass diagram into harmonic components along with the determination of their amplitudes and lengths of periods (waves), and then, using spectral analysis, draws a spectrogram in the form of an amplitude spectrum. It is spectral analysis that makes it possible to detect the hidden periodicity in the distribution of linear mass of the studied fiber stream [1, 2, 12]. An example of a spectrogram obtained with the Uster device is shown in Figure 6.
The individual bands on the spectrogram are an image of harmonic components, i.e., their relative amplitudes and wavelengths mapped on a logarithmic scale. The band is hatched when the harmonic component is repeated more than 25 times during the measurement, and unhatched when there are from 6 to 25 such repetitions. The longer the fiber stream is studied, the more harmonic components in the form of striations will appear on the spectrogram (at higher wavelengths), which enables a more accurate assessment of the technological process.
Each drawing mechanism in spinning machines introduces a certain short-term unevenness in the fiber stream, which is reflected on the spectrogram in the form of a drawing wave at small wavelengths; the individual harmonic components have slightly higher amplitudes. The dominant wavelength
Any disturbances in the proper course of the technological process are reflected on the spectrogram in the form of so-called “chimneys” and “humps.” A sample spectrogram of the yarn produced in a disrupted process is presented in Figure 7.
A mechanical error in the operation of the machine appears on the spectrogram in the form of a chimney—one of the harmonic components of the mass distribution of the fiber stream has a higher amplitude than the other components. According to the data provided by the Uster device manufacturer :
K ≥ B/2 – in the woven or knit fabrics there are clusters of yarn sections giving the effect of spots; K ≥ B – a very serious error requiring immediate interruption of production.
K ≥ B/2 – in the woven or knit fabrics there are clusters of yarn sections giving the effect of spots;
K ≥ B – a very serious error requiring immediate interruption of production.
The wavelength of such a harmonic component depends on the diameter
The most common harmonic components on the spectrogram caused by mechanical defects include:
eccentricity of rollers deformation of the lagging of the upper rollers non-parallel alignment of the rollers faulty or damaged grooving of the bottom rollers torsional and transverse vibrations of the rollers damage in the drive (damaged gears, incorrect meshing of gears, dirty gears, damaged drive belts, etc.) damaged or worn bearings damaged belts of the drawing mechanism.
eccentricity of rollers
deformation of the lagging of the upper rollers
non-parallel alignment of the rollers
faulty or damaged grooving of the bottom rollers
torsional and transverse vibrations of the rollers
damage in the drive (damaged gears, incorrect meshing of gears, dirty gears, damaged drive belts, etc.)
damaged or worn bearings
damaged belts of the drawing mechanism.
Mechanical defects can cause the occurrence of periodic errors of the following types:
sinusoidal – a single or less often double chimney on the spectrogram non-sinusoidal – on the spectrogram, a chimney at the basic wavelength and several smaller chimneys at the
sinusoidal – a single or less often double chimney on the spectrogram
non-sinusoidal – on the spectrogram, a chimney at the basic wavelength and several smaller chimneys at the
The appearance of double chimneys on the spectrogram is a result of insufficient measurement accuracy of the Uster Tester. The probability of their appearance decreases with increasing the number of measuring channels in the device [3,4,5].
A technological error in the operation of the machine appears on the spectrogram in the form of a hump, which occurs when several adjacent harmonic components of the mass distribution of the fiber stream have a higher amplitude than the other components. The maximum wavelength of harmonic components with an increased amplitude value depends on the average length
Harmonic components on the spectrogram caused by technological defects are formed as a result of improper movement of fibers in the drawing zone. The reasons may include:
poor composition fiber blend (e.g., too high a proportion of short fibers) too long distances between the rollers of the drawing mechanism poor selection of the total draft and partial drafts too low load on the upper drawing rollers too wide condensers sliding strips of drawing mechanism rollers.
poor composition fiber blend (e.g., too high a proportion of short fibers)
too long distances between the rollers of the drawing mechanism
poor selection of the total draft and partial drafts
too low load on the upper drawing rollers
too wide condensers
sliding strips of drawing mechanism rollers.
On the spectrogram obtained for yarn, it is possible to detect irregularities in the work, not only of the spinning machine, but also of the machines involved earlier in the technological process. The causes of the appearance of stretch waves (chimneys and humps) are dependent on the wavelength:
waves up to 3 cm – waves 3–50 cm – Waves 50 cm–5 m – waves above 5 m –
waves up to 3 cm –
waves 3–50 cm –
Waves 50 cm–5 m –
waves above 5 m –
Mechanical defects in the operation of spinning machines can also be detected using the tachometric method. For this purpose, a tachometer (revolution counter) is used, or kinematic calculations of the drive elements of the machine are performed.
If the wavelength of the chimney on the spectrogram is
By means of a tachometer or kinematic calculations, an element with the calculated rotational speed
Errors within the range of very small wavelengths (λ < 5 cm) may also appear on the spectrogram. The causes of such errors may include:
vibration of the machine and/or the drawing rollers (an error difficult to detect) faulty grooving of the driving rollers (irregular or too deep grooves); bundles of fibers are captured at intervals of the groove scale
vibration of the machine and/or the drawing rollers (an error difficult to detect)
faulty grooving of the driving rollers (irregular or too deep grooves); bundles of fibers are captured at intervals of the groove scale
Most drawing mechanisms in spinning machines are equipped with belts to control the movement of the fibers. A damaged belt can also be a source of error in the operation of the machine, and the wavelength of such an error is recorded on the spectrogram as
Incorrect meshing of the drive wheels may also be the cause of the error visible on the spectrogram. As a result of too small or too long a distance between the cooperating gears, a harmonic component with a wavelength
Errors on the spectrogram can be caused by defects in the twisting and winding system of the roving or spinning machine. The reasons for this type of error may include:
eccentric setting of spindles damaged spindle bearings wings set eccentrically in relation to the bobbin.
eccentric setting of spindles
damaged spindle bearings
wings set eccentrically in relation to the bobbin.
The wavelength of the harmonic components on the spectrogram (chimneys) depends on the diameter of the bobbin from which the fiber stream for testing is sampled and fall within the following range:
When performing spectral analysis of yarn or any intermediate spinning product, it is not enough to have only a spectrogram obtained on the Uster Tester device. It is also necessary to know the parameters of the technological process such as: diameters and speeds of rollers of the drawing mechanism, length of strips in the drawing mechanism, intermediate drafts, rotational speeds of individual drive wheels, release speed of machines, etc. The values of these parameters are usually known and once measured or calculated, they can be used repeatedly to carry out such analyses for a particular technological process.
An example of spectral analysis of worsted yarn, made of a wool and polyamide fiber blend 70/30 of an average length of 80 mm, based on the spectrogram obtained in Figure 8, is presented below.
A diagram of the drawing mechanism of the spinning machine from which the yarn was taken for analysis is shown in Figure 9.
The operating parameters of the spinner and the rotational speeds of the selected drive wheels, the work of which seemed incorrect after assessing the condition of the machine drive, are presented in the box.
The yarn spectrogram (Figure 8) clearly shows two chimneys, i.e., harmonic components of the distribution of the yarn linear mass, whose amplitudes are much higher, as well as a hump resulting from a technological error. The chimneys occur at
for the output zone
for the feed zone
for the output zone
for the feed zone
The analysis of errors visible on the yarn spectrogram in the form of chimneys and humps allows one to determine the probable causes of their formation.
For a chimney located at wavelength
For a chimney located at wavelength
For a hump, the maximum amplitude of which falls on the wavelength
It is noteworthy that the reason for the appearance of a chimney on the spectrogram cannot always be clearly identified. This is applicable also to the case under consideration. If the upper and lower rollers have the same diameter (which happens very rarely), then only a direct assessment of their condition on the machine allows one to identify the site of damage more accurately. Additionally, the drive wheels of the machine or the belts controlling the movement of the fibers in the drawing mechanism can yield an error at the same wavelength on the spectrogram as the damaged roller of the drawing mechanism.
Spectral analysis of the linear mass distribution of the fiber stream based on the results obtained on the Uster Tester is the simplest and fastest method of assessing the quality of linear textile products already at the stage of their manufacture. Any irregularities in the spectrogram structure for the analyzed fiber stream are the result of either mechanical damage or technological errors in the operation of spinning machines. Analysis of the spectrogram allows one to detect and locate these errors and damages with fairly high accuracy, which makes it possible to eliminate them. To perform spectral analysis, it is required to have a thorough knowledge of the technological process, the operating parameters of the machines in the technological line, and the kinematics of the drives of the individual machines. A spectrogram of any fiber stream contains the entire history of its production, which makes it possible to detect errors also in earlier stages of processing. However, spectral analysis does not always give unambiguous results. It is often necessary to verify the obtained results directly on the machine in order to identify a malfunctioning element or zone.
Spectral analysis is currently the basic tool for assessing the quality of flat textile products already at the stage of yarn formation.
|- for carded cotton yarn||1.8 ÷ 2.6|
|- for combed cotton yarn||1.3 ÷ 1.6|
|- for yarns of man-made staple fibers||1.5 ÷ 2.2|
|- for worsted woolen yarn||1.1 ÷ 1.4|
|- for carded woolen yarn||1.4 ÷ 2.1.|Automatic Identification Of Wrist Position In A Virtual Environment For Garment Design Pressure Evaluation Of Seamless Yoga Leggings Designed With Partition Structure Tensile Properties Analysis Of 3D Flat-Knitted Inlay Fabric Reinforced Composites Using Acoustic Emission From Raw To Finished Cotton—Characterization By Interface Phenomena A Study on the Woven Construction of Fabric Dyed With Natural Indigo Dye and Finishing for Applying to Product Design for Home Textile Products A Calculation Method for the Deformation Behavior of Warp-Knitted Fabric Nondestructive Test Technology Research for Yarn Linear Density Unevenness Blend Electrospinning of Poly(Ɛ-Caprolactone) and Poly(Ethylene Glycol-400) Nanofibers Loaded with Ibuprofen as a Potential Drug Delivery System for Wound Dressings Study On Structure And Anti-Uv Properties Of Sericin Cocoons Fit And Pressure Comfort Evaluation On A Virtual Prototype Of A Tight-Fit Cycling Shirt A Fabric-Based Integrated Sensor Glove System Recognizing Hand Gesture Developing Real Avatars for the Apparel Industry and Analysing Fabric Draping in the Virtual Domain Review on Fabrication and Application of Regenerated Bombyx MoriSilk Fibroin Materials The Effects of Sensory Marketing on Clothing-Buying Behavior Transport of Moisture in Car Seat Covers Review on 3D Fabrication at Nanoscale Investigation of the Performance of Cotton/Polyester Blend in Different Yarn Structures Design of Clothing with Encrypted Information of Lost Children Information Based on Chaotic System and DNA Theory Determination of Sewing Thread Consumption for 602, 605, and 607 Cover Stitches Using Geometrical and Multi-Linear Regression Models Application of Spectral Analysis in Spinning Measurements Polyaniline Electrospun Composite Nanofibers Reinforced with Carbon Nanotubes Current Development and Future Prospects of Designing Sustainable Fashion Effect of Surface Modification of Himalayan Nettle Fiber and Characterization of the Morphology, Physical and Mechanical Properties Investigation of Actual Phenomena and Auxiliary Ultrasonic Welding Parameters on Seam Strength of PVC-Coated Hybrid Textiles Modeling Lean and Six Sigma Integration using Deep Learning: Applied to a Clothing Company Comparative Analysis of Structure and Properties of Stereoscopic Cocoon and Flat Cocoon Effect of Different Yarn Combinations on Auxetic Properties of Plied Yarns Analysis of Heat Transfer through a Protective Clothing Package Smart Textile for Building and Living Investigation of Twist Waves Distribution along Structurally Nonuniform Yarn Preliminary Experimental Investigation of Cut-Resistant Materials: A Biomimetic Perspective Durable Wash-Resistant Antimicrobial Treatment of Knitted Fabrics Study on the Thermal and Impact Resistance Properties of Micro PA66/PU Synergistically Reinforced Multi-Layered Biaxial Weft Knitted Fabric Composites Fea-Based Structural Heat Transfer Characteristic of 3-D Orthogonal Woven Composite Subjected to the Non-Uniform Heat Load Comfort-Related Properies of Cotton Seersucker Fabrics Investigating the Effect of Recycled Cotton Included Fabrics on the Thermal Behaviour by Using a Female Thermal Manikin Investigation of Surface Geometry of Seersucker Woven Fabrics Liquid Moisture Transport in Stretched Knitted Fabrics Study on Process Optimization and Wetting Performance of Ultrasonic-Oxidized Wool Fiber Thermal Resistance of Gray Modal and Micromodal Socks Conductive Heat Transfer Prediction of Plain Socks in Wet State Textronic Solutions Used for Premature Babies: A Review Effect of Lycra Weight Percent and Loop Length on Thermo-physiological Properties of Elastic Single Jersey Knitted Fabric Texture Representation and Application of Colored Spun Fabric Using Uniform Three-Structure Descriptor Approach to Performance Rating of Retroreflective Textile Material Considering Production Technology and Reflector Size Influence of Multilayer Interlocked Fabrics Structure on their Thermal Performance Experimental Investigation of the Wettability of Protective Glove Materials: A Biomimetic Perspective Mechanical Properties of Composites Reinforced with Technical Embroidery Made of Flax Fibers Development of the Smart T-Shirt for Monitoring Thermal Status of Athletes Assessment and Semantic Categorization of Fabric Visual Texture Preferences Application of Coating Mixture Based on Silica Aerogel to Improve Thermal Protective Performance of Fabrics A Biomimetic Approach to Protective Glove Design: Inspirations from Nature and the Structural Limitations of Living Organisms Washing Characterization of Compression Socks Estimation of Seams in Paraglider Wing Development of a Small, Covered Yarn Prototype Numerical Prediction of the Heat Transfer in Air Gap of Different Garment Models Fabrication and Characterization of Fibrous Polycaprolactone Blended with Natural Green Tea Extracts Using Dual Solvent Systems Archaeology and Virtual Simulation Restoration of Costumes in the Han Xizai Banquet Painting Modeling of Material Characteristics of Conventional Synthetic Fabrics