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1.
The influence of thread twist on alterations in fibers` mechanucl properties
Andreja Rudolf, Jelka Geršak, 2006, original scientific article

Abstract: In order to design high-quality threads, it is necessary to know the properties of threads and fibers, as well as the loadings and deformations which may occur during the sewing process. Thread properties depend on the mechanical properties of the fiber and the constructional parameters of the thread and its surface treatment, which directly influence sewing performance.The mechanical properties of a thread primarily depend on the fiber mechanical properties and the amount of twist. Knowledge of the thread dynamic loadings during the sewing process, depending on the number of turns and the lubrication method, is important for planning the required processing properties of the thread. This paper presents research into the influence of thread twist and the lubrication method on the mechanical properties and dynamic load of PES core-spun thread and its fibers. Research into the mechanical properties of the different twisted and surface treated threads, and separated fibers was carried out for this purpose. The influence of threaddynamic load during a sewing process was also researched regarding any alterations in the mechanical properties of the threads and separated fibers. Analyses of the results show that the amount of twist depends on the mechanical properties of the thread and its constituent fibers, whilst the method of surface treatment is based on the specific mechanical properties of the thread. A dynamic load causes greater or smaller thread deformations, which is reflected in changes in the thread and fiber mechanical properties. The occurred changes depend on dynamic load, amount of twist, and the lubrication method, which is confirmed with statistical analysis of the measured results.
Keywords: garment manufacturing, sewing, threads, textile fibres, surface treatment, dynamic loads, mechanical properties, amount of twist
Published: 30.05.2012; Views: 1476; Downloads: 18
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2.
Colour of polyester thread, in regard to different dyeing procedures and dye-bathsć ph
Darinka Fakin, Alenka Ojstršek, Alenka Majcen Le Marechal, 2008, published scientific conference contribution

Abstract: The aim of the presented research was to investigate the impact of different dyeing procedures (conventional two-baths and one-bath) and dye-bathsć pH (acidic and alkaline) on the exhaustion of five disperse dyestuffs, differing in colour (yellow, red, blue, violet and black). The dyeing of polyester thread was carried-out at two concentrations (1 and 3%). The concentration of dye residual in dye-bath effluents were determined by absorbance measurement, followed by colourimetrical evaluation of dyed samples, and colour differencescalculation. The obtained results indicating superior dye exhaustion throughout alkaline one-bath procedure in comparison to conventional polyester dyeing that affect also on reduction of dyeing time, amount of dye-bath wastewaters, and energy consumption.
Keywords: polyester sewing, dyeing, disperse dyestruffs, colourimetry
Published: 31.05.2012; Views: 834; Downloads: 19
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3.
Structure-properties relations of the drawn poly(ethylene terephthalate) filament sewing thread
Andreja Rudolf, Majda Sfiligoj-Smole, 2008, original scientific article

Abstract: This article presents research into draw ratio influence on the structure-properties relationship of drawn PET filament threads. Structural modification influence due to the drawing conditions, i.e., the birefringence and filament crystallinity, on the mechanical properties was investigated, as well as the shrinkage and dynamic mechanical properties of the drawn threads. Increasing draw ratio causes a linear increase in the birefringence, degree of crystallinity, filament shrinkage, and a decrease in the loss modulus. In addition, loss tangent and glass transition temperature, determined at the loss modulus peak, were increased by drawing. The observed structural changes influence the thread's mechanical properties, i.e., the breaking tenacity, elasticity modulus, and tension at the yield point increase, while breaking extension decreases by a higher draw ratio.
Keywords: PET sewing thread, drawing, birefringence, DSC, DMA, mechanical properties
Published: 31.05.2012; Views: 1100; Downloads: 52
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4.
Thread loadings in different measuring positions on the sewing machine
Darja Žunič-Lojen, Jelka Geršak, 2005, original scientific article

Abstract: The knowledge of sewing thread tension determined at different measuring locations on the sewing machine is the basis for the definition of the loading magnitudes acting during the stitch formation process and the locations at which they appear, concerning the stitch cycle or the main shaft turn of the sewing machine. During the stitch formation process the sewing thread is exposed to the highest tension in the region between the tension regulator and the thread take-up lever, following by tension in the region between the take-up lever and the needle and in the region in front of the tension regulator. Dynamic tension and tension force are also dependent on stitch velocity.
Keywords: textile industry, sewing, kinetics of sewing, thread, dynamic thread loadings
Published: 01.06.2012; Views: 1203; Downloads: 48
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5.
Computer simulation of needle and take-up lever mechanism using the ADAMS software package
Darja Žunič-Lojen, Karl Gotlih, 2003, original scientific article

Abstract: A knowledge of the interactions between a sewing machinećs mechanisms and the sewing thread in the stitch formation process should help us to understand thread loadings in the sewing process. The aim of this work is to analyse the needle bar's kinematics with the thread take-up lever by using computer simulation. A cyclogram was drawn on the basis of modelling and kinematic simulation of a needle bar with a thread take-up lever, and measurements of the thread tension forces in the sewing process. This cyclogram enables analysis of the interactions between the thread and the elements of the sewing machine. The results of these simulations are curves that describe the movements at characteristic points on the mechanism. These give the possibility of pinpointing the exact positions of the mechanism's elements with respect to the main shaft rotation in the sewing machine.
Keywords: textiles, garment manufacturing, sewing, thread, stitch fomation, thread loading, cyclogram, computer simulation
Published: 01.06.2012; Views: 1263; Downloads: 16
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6.
Workloads and standard time norms in garment engineering
Zvonko Dragičević, Daniela Zavec Pavlinič, Jelka Geršak, 2002, original scientific article

Abstract: Posibilities of new methods for measuring loading and standard time norms are presented, as applied in the field of garment engineering. Measurements deescribed are performed on modern measuring equipment designed to measure and perform computer analysis of temporal values of processing parameters in sewing operation and simultaneously record in two planes using a video system. The measuring system described was used to investigate sewing operation for the seam on a ladies' fashion suit, 52 cm long. For the operation investigated, method of work employing the MTM (Methods Time Measurements) system with analysis of basic movements was selected. The MTM system used shows that normal time for the operation in question is around 429.3 TMU (15.5 s). Investigations of workload imposed on the worker according to the OADM method were done simultaneously, and total ergonomic loading coefficients of Ker=0.082 was established, thus determining the time necessary to organise the process of work as 464.5 TMU (16.7 s). Simultaneous measurements of time and dynamic changes of processing parameters, as well as logical sets of movements, are important for defining favourable operation structures, time norms ergonomically designed systems of work and workplaces in garment engineering, as early as in the phase of designing operation. The investigations described make possible to find optimal distribution of working elements and zones of reach important for ergonomic designing and/or re-designing of workplaces, which results in considerably reduced level of fatigue in work optimal quality level, higher degree of utilisation of equipment installed and lower manufacturing costs.
Keywords: garment engineering, sewing, standard time norms, norms, time study, work study, MTM, motion timestudy measurement
Published: 01.06.2012; Views: 915; Downloads: 29
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7.
Investigations of the structure and process parameters of sewing operation
Daniela Zavec Pavlinič, Zvonko Dragčević, Dubravko Rogale, Jelka Geršak, 1999, original scientific article

Abstract: An original measuring equipment and a system for investigating process parameters of the sewing operation structure and for establishing optimal working methods and real working conditions of the man-machine system in garment sewing are presented. The measuring equipment consists of a process parameter measuring and data storing system and a bi-plane video recording system. The measuring and data storage system is equipped with four sensors which measure the rotation speed of the main shaft, the movements of arms in the picking-up and laying-off zones, and the movements of the pedal regulator used to control the sewing dynamics. The bi-plane video recording system is used to record simultaneously the working movements (working methods) performed at the discussed workplace. From the process parameter measurements graphs for the technological operation structure are obtained, including the duration of individual suboperations and changes occuring due to pedal regulator movements. The bi-plane video recording system investigates the working method employed, the basic movements and and the optimal logical sets of movements, as well as the cyclograms of the movements used to define space and time values. The results obtained are compared with the MTM results, and the differences between them are presented.
Keywords: textile industry, garment engineering, sewing operation structure, process parameters, bi-plane video recording, workplace design
Published: 01.06.2012; Views: 1221; Downloads: 21
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