PERFORMANCE PROPERTIES OF THREAD SEAMS OF KNITTED-BASED MEMBRANE MATERIALS

The article is devoted to the study of the strength and wear resistance of thread seams of membrane materials on a knitted basis. The characteristics of the composite membrane three-layer material are given and the modes of its stitching and the test method are substantiated. Investigations of material cutting through with a needle were carried out and the geometry of the sewing needle point was chosen. The results of the study of the strength of thread seams made along of the front layer of the material before and after modelling the operational tensile loads along and across the seam are presented. 15000 load-unload cycles were simulated, stretching the sample by 10 % of the seam length. As a result of a full factorial experiment, it was found that the linear density of the threads and the diameter of the needle have the greatest effect on the strength and wear resistance of the thread seams of the composite material. The influence of the sewing frequency is ambiguous for the parameter of the wear resistance of the seam when stretched along and across the line.

The study of needle type influence on woven fabric surface area during the sewing process

The aim of this study was to investigate the damage to cotton fabrics (ticking and damask) caused by stitching with three types of needle point shapes (R, SES and SUK) and four needle sizes (70, 80, 90 and 100 Nm). Damage to the yarn and the surface area of the hole were investigated. Based on the results, it can be concluded that two types of damage occur during sewing: the needle passes through the warp/weft (it displaces the yarn) and the needle damages the warp/weft. An analysis and comparison of the surface area of the holes was carried out, obtained by a computer program based on microscopic images. The results show greater damage to the yarn at the needle piercing point in the ticking due to higher density, friction and low yarn migration. The largest surface area of the holes was produced when sewing with SUK-designated needles on ticking and damask. When sewing damask, R-designated needles cause the least damage to the piercing point, whereas SES-designated needles give the best results when sewing the ticking. Thread damage was further confirmed by testing the tensile properties of the yarn at the needle piercing points.

Comparative Study of Needle Penetration Forces in Sewing Hems on Toweling Terry Fabrics: Influence of Needle Type and Size

In this paper, an industrial case study comparing the use of different needles in the production of hems in towels is presented. The study aims to assess the sewability of the fabrics, quantified by needle penetration forces. The market offers an interesting range of options for the needle, regarding the geometry of the needle point, surface finishing, and sizes. However, in practice, the choice is difficult, namely due to the lack of quantitative data that may support the empirical evaluation made by the sewing technicians. The work aims to assess how the needle type and size relate to the resulting needle penetration forces. Three terry fabric structures, produced by a home textiles manufacturer, were tested using needles of different sizes, points, and coatings. Needle penetration forces were measured on a sewability tester prototype, previously designed and developed, based on an instrumented overedge sewing machine. It was found that needle penetration forces present very significant differences with small size increments, needle coating also influences forces significantly, and different needle points produce only slight differences, significant only on some of the fabrics that were tested.

Problems with perfect-looking two-needle decorative seams in the manufacture of leather car seat covers

This study objectively evaluates the uneven appearance of the two-needle decorative seams of leather seat covers. The investigation is based on both measurement of the stitch slant angle by image analysis and measurement of the penetration force influenced by different cutting points of the needles. To record the unevenness the new parameter, the difference of the stitch slant between the right- and left-hand sides of the seam was evaluated. Further, the interrelation ship among penetration force differences of the stitch slant and type of needle point was searched for to meet the requirements of car producers for a perfect appearance of decorative seams. The degree of uneven seam was measured within subjective visual evaluation, too. Four natural and two artificial leathers were tested. A combination of two threads and four needle points was applied to the tested leathers. It was confirmed that the uneven appearance was influenced by the type of leather, the point of the sewing needle and by the sewing thread. The selection of the needle point influenced the size of the force required for penetrating the leather. It was determined only in half of the cases that the smaller the force of penetration, the more even the appearance of the decorative seam. In most cases, using the cutting point LR, the left seam looked less slanted than the right one. Conversely, when using the cutting point for straight stitch appearance, that is, DH, the left stitch looked straighter than the right one. The causal link between the new parameter Δβ and the suitability of the applied needles and threads for leather materials was found.

Identification and mapping of real acupoints in the anatomical topography of Boa constrictor

Acupuncture is a therapy of the traditional Chinese medicine technique, which over the years has been widespread in the West. Defined as a needle-point treatment technique (acupoints), exactly preconfigured in the body to produce a specific physiological reaction to restore the balance between the function of conflicting states and homeostasis, alternating states of energy and thus maintain the ideal organ and body organization. Thus, the objective of this study was to map and describe the main points of acupuncture in the species Boa constrictor , and their indications to promote the balance of this species. The unprecedented result of the mapping was the discovery of specific acupoints with individual location indications without distribution in specific meridians and dispersedly distributed in the body.

Device for Checking Acuteness of Injection Needle Point and Test Methodology

The paper presents a designed device for checking acuteness of injection needle point and development of methodology for conducting corresponding tests. Basic information on disposable injection needles including their purpose, structural elements and requirements for the state of their points. The paper describes a standard method for checking acuteness of injection needle point which is based on measuring maximum force for piercing a high-pressure polyethylene film of a certain thickness by an injection needle during its translatory motion at a given speed. A description is given of the design and operating principle of the developed device that implements this method for checking acuteness of injection needle points. Main provisions of the developed methodology for conducting these tests including sequence and content of actions during their execution have been set out in the paper. Results of the experiments on verification of acuteness in injection needle points of four-diameter confirm practical use validity of the developed device and methodology for conducting corresponding injection needle tests. The obtained oscillograms on changes in the force acting on a needle in the process of polyethylene film piercing are highly informative and that makes it possible to investigate in detail specific features at all stages of the process being studied, including both the stage of film piercing by a test needle and the subsequent stage of removing it from the contact with the film.