The Influence of Stitch Density and of the Type of Sewing Thread on Seam Strength
Having in mind the complex problems of technological process of sewing, as well as general demands for seams produced in garment production, this research should contribute the development of sewed seams breaking forces. Thus, many measurements of seam breaking forces have been conducted. These measurements enable us to define optimal strength of seam strength that improves the compliance of sewed seams parameters. This paper deals with the influence of the thread type and stitch density on the seam strength. The breaking forces and elongations at break were determined by the standardized method (SRPS 2062) and fabric (tape method) according to SRPS EN ISO 13934-1. Fabric samples used for seam testing were sewed by seam (1.01.01) and stitch type 301 with stitch densities 3, 4 and 5 cm. Optimal seam strength (130.9 Ncm) on the fabric T71, and at the same time the highest strength, has been noticed at the samples with seam line in weft direction with stitch density 5 cm, sewed with polyester thread 20x2 tex count, while on fabric T71 that value is 115.9 Ncm. According to obtained results, it can be concluded that stitch density (3 cm ÷ 5 cm) and the type of sewing thread (cotton and polyester, K1 ÷ K5) have great influence on defining seam sttrength, their inconsistency may lead to great differences in seam behavior.
MECHANICAL BEHAVIOUR OF SEAMS ON TREATED FABRICS
The purpose of this work is to find out the performance of seams after successive treatments applied to fabric. Performance of seams is given by their load/elongation behaviour . In this study , woven fabrics are chosen to investigate the effect of their chemical and mechanical finishing process (desizing, scouring, bleaching, dyeing and sueding) on the behaviour of the seams. Three factors have been studied: T reatment, Density (number of stitches per centimeter) and seam direction (wef t or warp direction). T wo responses are measured: seam elongation at break and seam breaking force. The initial fabrics properties before stitched have an important impact on the behaviour of the seams. This work explains that it is more useful to study the yield point than the rupture point; because for the wear , the elastic phase (recovery) is more import ant than the plastic phase. Studying yield point of seams explains better the reality limit of use of stitched fabrics. The increase of the number of stitches per centimetre ameliorates the breaking resistance of seam, but not the elongation at break. However the density has small effects on the yield point.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.