PROPERTY ANALYSIS OF SKIRTS MADE FOR READY-TO-WEAR COLLECTION.PART I: TENSILE TESTING OF SEWING THREADS AND WOVEN FABRICS

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1 PROPERTY ANALYSIS OF SKIRTS MADE FOR READY-TO-WEAR COLLECTION.PART I: TENSILE TESTING OF SEWING THREADS AND WOVEN FABRICS ABSTRACT Rodica Harpa Gheorghe Asachi Technical University of Iasi, Romania This study aims to emphasize several concerns regarding women's skirts design, namely the connections between special types of sewing threads delivered by the supplier for the garment manufacture and fabrics' selection for specific destination. The cause-effect analysis referring to the most important properties required by the designed garment was achieved. The testing methodology was based on the actual standards for evaluation of the yarns and woven fabrics' tensile properties. The conclusion of this paper was that sewing threads and woven fabrics have important effects on the skirts design, for expected quality profile at wear. Key Words: Sewing threads, woven fabrics, tensile testing, designed garment 1. INTRODUCTION Garments of the same generic category differ depending on the number of fabric layers and their combination within the product, on the manufacturing mode and on further processing (finishing) so, in order to meet the customers' specific demands, even since the design stage, it is important to consider the sewing thread suppliers' recommendations as a starting point in selecting it, [1, 2]. The success of the sewing process depends on the sewing threads characteristics that can have an effect on the garment features (appearance, comfort, and durability) for a specific end use, [1, 3, 4]. Regarding the production of skirts, different types of sewing threads (from very fine to coarser) are involved, always in connection with fabrics layer characteristics, [2]. Every type of garment has specific use properties, mainly depending on the number of layers that one could obtain from different materials, [1]. Many studies indicate that nowadays garment industry has an ever-higher demand for a variety of sewing threads, because of the diversity of raw materials and the widening of fields using textile materials, [1, 3]. Different approaches about the quality level of the garment underline major categories of features that are usually involved: the design features (given the raw materials, manufacturing particularities, sewing parameters and necessary finishing techniques) and the wearing features (namely physiological, physical and aesthetic features). Hence, the quality control in apparel manufacturing must complete an overall assessment, [5]. Previous papers have approached the garment quality issue by means of the seam quality; because the quality requirements of sewing threads have implications both during the sewing process itself and during the subsequent life of the garment, some techniques for the proper selection of the threads for an appropriate sewability in leather clothes manufacturing were suggested, [5, 6]. This study aims to search the effect of the mechanical properties of fabrics and sewing thread, on women dresses and more precisely, on skirts. 465

2 2. EXPERIMENTAL 2.1 Materials The experiment was carried out on three fabrics and on two selected sewing threads, proposed in the skirt design stage, of a ready-to-wear collection. Three types of fabrics were chosen for experimental analysis (one for coating and two option for lining) and their characteristics are presented in Table 1. Table 1. Main characteristics of investigated fabrics Fabric symbol F1 F2 F3 Skirt layer coating lining lining Weave plain twill twill Raw material PES 42%/ CO 32%/ PES 100% CA 67%/PES 33% WO 10%/ CV 8% / PA 4% / PAN 4% Mass per square meter (g/m 2 ) Thickness (mm) Two types of Coats Epic industrial sewing threads, were chosen in our study, given the required final quality of skirt designed [7], and their features are presented in Table 2. According to the supplier [2], the types of sewing thread should be selected from the Coats product range first, depending on the particular customer needs. The Coats Epic sewing thread is a polyester-wrapped thread with a polyester filament core. For this study, the corespun thread includes two multifilament cores (i.e. 2 ply). This combination gives optimum tenacity in the threads designed for versatile uses (including fashion apparel), with good behavior in sewing processing, achieving seam appearance and seam strength, as well. Table 2. Overall sewing profile of skirt designed Skirt designed Stitch code Stitch type Lockstitch (two-thread; Nt & Ut ) Overedge (three-thread; Nt & 2 Ut ) Overedge (fourthread; 2 Nt & 2 Ut) Blindstitch (single thread; Nt) EPIC sewing thread Needle thread (Nt) ; Under thread (Ut) selected for fabrics, for F1: 21 / 150 (color code*); for F2 : 21 / 150 (color code**) Tex / Tkt for F3: 24 / 120 Needle size, Nm for Tkt 150 : Nm ; for Tkt 120 : Nm

3 2.2. Methods Experiments were conducted in two stages: first, the cause and effect analysis referring to the most important factors that may influence the achievement of quality skirts and second, tensile testing of the fabrics and sewing threads, selected to develop the skirt from the collection The cause and effect analysis may bring out the contributing factors of usually known effects. In the fishbone diagram, the first listed are the main factors, most likely the causes of the effect. The idea is to show for every source cause the detailed successive sub-causes that could potentially contribute to a particular effect, [8]. In a previous study [5] the main causes and the sub-causes that could affect sewability were identified; as a result, the cause-effect diagram revealed the connections between sewing threads quality criteria and seam quality criteria for desired sewability. In this paper, the approach of this tool was necessary to quantify the main causes and the subcauses that may affect the optimum quality of the skirt, namely some properties necessary for specific destinations The specimens for tensile tests (fabrics and sewing threads) were performed according to standards [1] and are briefly summarized below. Tensile testing of the woven fabrics according to the strip method [9], was deployed under the following conditions: Testing machine: Tinius Olsen Model H5kT (the single column materials) with flat jaws, 200 mm free gauge for fabric fasten, 30±5 seconds testing time, 100 mm/min testing speed and semiautomatic control. Sampling: five single tests on the warp and on the weft, with 50 mm x 300 mm size each. Tensile testing of the sewing threads was conducted in compliance with the standards [10], under the following conditions: Testing machine: USTER TENSORAPID 4 with clamping device for single technical yarn testing, 20±3 seconds testing time, 500 mm/min clamp speed and automatic control. Sampling: tests of five sewing thread cones, 20 tests per cone, 500 mm test length. Fabrics and sewing threads were conditioned at 65 ± 4% relative humidity and 20 ± 2 C for 24 hours before measuring. 3. RESULTS AND DISCUSSIONS 3.1. Configuration of the cause-effect diagram for an optimum quality skirt Figure 1 shows the cause and effect diagram, useful for highlighting the factors that may affect the final quality of the skirt. 467

4 Figure 1. The Cause and Effect Diagram for the Quality of the Skirt In the above configuration, were included the main causes and sub-causes leading to the expected effect, namely the final quality of the skirt. In practice, the main causes which should be considered for improving the product quality were the following: base material (the coating fabric), secondary material (the lining) and threads for sewing each of the two layers of material, garment design and manufacturing. The overall sub-causes selected are also important as quality criteria for decisive functions to achieve in skirts. No matter what niche is targeted, ladies-wear designed by means of engineering methods must have functional and aesthetical features. For that reason, each fabric layer and sewing threads used in skirts manufacturing should provide durability, including an optimum level of behavior to tensile stresses Tensile testing of the fabrics Table 3 presents the average values of the tensile properties obtained for the tested fabrics with Tinius Olsen H5kT. Table 3. Tensile values of the tested fabrics Fabric symbol F1 F2 F3 Skirt layer coating lining lining Warp Weft Warp Weft Warp Weft Breaking force (N) Elongation (%) Breaking length (km)

5 The two materials chosen for the skirt lining (F2 and F3) were preferred for the collection design, considering the colors, the raw material and quality criteria, see Table 1. In Table 3, the average values of the tensile properties show notable differences in the tensile behavior of the two lining materials that have close values for mass per square meter and for thickness. Considering the skirt assembly, we can estimate the effect of elongation as the tiebreaker between the two lining materials; therefore, a combination of materials to ensure durability and appearance at wearing can be one between F1 and F2, see Table Tensile testing of the sewing threads Table 4 presents the average values of the tensile properties obtained for the tested sewing threads with USTER TENSORAPID 4 Table 4. Tensile values of the tested sewing threads Thread Ticket EPIC 150 EPIC 150 EPIC 120 Nominal size,ttex Color code Breaking force (cn) Elongation (%) Breaking length (km) Sewing fabric F1- coating F2- lining F3- lining The manufacturing regulation of sewing threads suppliers established that the higher the ticket number, the finer the sewing thread. Therefore, the average values of the tensile properties for the tested EPIC sewing threads, illustrate that the sewing thread strength increases with thread size (the lower ticket number). Sewing thread breaking length versus sewing ticket number fit in a tight range of variation for both, fine and coarse threads. However, the polyester corespun threads with the same ticket number (EPIC 150) have different tensile properties (breaking force and elongation) most likely, due to the dyeing effects (i.e. color code, see Table 2). From the above summarized experimental values it can be concluded that, the preferred combination for sewing a skirt is EPIC 150 for both materials (coating and lining). 4. CONCLUSIONS Skirts quality requirements are rigorous, aimed to ensure the functional and aesthetic properties when wearing the garment. The sewing thread must have good sewability and this means the ability to join properly fabrics for coating and for lining, which must last as much as the whole garment. In order to improve the overall quality of the skirt, during the sewing process and during the wearing, it was important to assess the behavior of some versions of fabric and sewing thread at tensile testing for mechanical features evaluation. The results reveal a potential of the presented approach in a selection of the fabrics and sewing threads for garments design, namely skirts, for expected quality profile at wearing. 469

6 5. REFERENCES [1] Sewing and Embroidery Threads. Basics. Vol.1, (2008), AMANN & Soehne GmbH & Co. KG. Available on [2] World Coats of Epic, Available on [3] PAVLINIC, D.Z. et al, Predicting Seam Appearance Quality, Textile Research Journal, 2006, Vol. 76, No. 3, pp Available on [4] MANDAL, S., NANDITA, A., An Overview of Sewing Threads Mechanical Properties on Seam Quality, Pakistan Textile Journal, 2010, Vol.1, pp Available from: [5] HARPA, R., Quality Garment By Means Of Quality Seam, Proceedings of the 7th International Conference Management of Technological Changes (MTC-2011), Alexandropoulos, Greece, September 1 st 3 rd, 2011, Book 1, pp [6] HARPA, R., Approach to Evaluation of the Sewing Threads Designed for Leather Products, Book Of Proceedings International Textile Clothing & Design Conference (ITC&DC-6 th ), October 7th 10 th, 2012, Dubrovnik, Croatia, pp [7] MORARI, A.S., Seam Quality: Durability Factors, Masters Thesis (Directed by HARPA, R.), Iasi, Romania, 2012, 58 pp (in Romanian) [8] OAKLAND, J.S., Statistical Process Control, 5 th edition, Butterworth-Heinemann, Oxford, 2003 [9] SR ISO 5081:1991. Textiles. Woven Fabrics. Determination of Breaking Strength and Elongation. Strip Method(in Romanian) [10] SR EN ISO 2062:2010 Textiles. Yarns from Packages. Determination of Single-End Breaking Force and Elongation at Break Using Constant Rate of Extension (CRE) Tester(in Romanian) 470