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In this paper, XIANGRONG XI and ISAO AJIKI define an actual overfeed ratio depending on the recovered length of an overfed seam. In particular, the effect of the actual overfeed ratio on the bending properties of the overfed seam was measured and the effect of fabric recovery on the fabric overfeed ratio was investigated. The results show that, for all samples, the natural curvature of an overfed seam increases proportionally as the actual overfeed ratio increase, which is different from the situation with the overfeed ratio. The two definitions of actual overfeed ratio and overfeed ratio can be connected by factor η, which is affected by stitch length, and by the recovery and compressive properties of fabric. The results also show that the factor provided the same varying tendency as the fabric recovery ratio, and that the differences between the factor and the recovery ratio depended on the kind of fabric involved.

The mechanical properties of fabric longitudinal extension and compression, shear and bending have an important influence on the performance of fabrics during tailoring and also on the performance of garments during use. Fabrics are overfed or underfed in tailoring during the sewing operations in such a way that longitudinal compression and extension are allowed in the fabric plane in order to produce the three‐dimensional shape or fullness of the garment. Fabric buckling or puckering at the seams should not occur, or if it does, should be removed during subsequent steam pressing operations. An experiment is described to measure the maximum limit of overfeeding that is possible during seaming without the subsequent formation of seam puckers. The relationships are studied between the maximum degree of overfeed, the bias angle between the feed direction and the fabric warp or weft, fibre type and fabric mechanical properties, especially fabric formability defined as the product of fabric bending rigidity and fabric longitudinal compressibility. When fabrics are extended or compressed longitudinally at a bias angle to the warp or weft direction during seaming in order to produce garment fullness, the warp and weft threads are rotated relative to each other in such a way that a local shear deformation is applied to the fabric adjacent to the seam‐line. Measurements are reported of the variations in the local shear angle along the shoulder seam‐line of a men's jacket and the measured values are related to the high degree of overfeed required in the bias direction in this area of the garment. Finally, hygral expansion measurements for wool fabrics and yarns unravelled from the fabrics are measured and compared for six different wool fabrics.

In Parts 1 and 2 of this series of papers, we have investigated the important mechanical and physical properties of fabrics which determine their performance during tailoring especially fabric tensile, shear, bending and dimensional properties. The conditions for structural balance of seams has been quantitatively evaluated as well as the relationship between the degree of fabric overfeed during sewing and the natural curvature or curling couple of the seamed fabric assembly. Fabric forming and draping behaviour is strongly dependent on fabric bending and the fabric membrane properties of extension, longitudinal compression and shearing in the fabric plane. In this paper, the influence of these basic fabric mechanical properties on subjectively assessed garment appearance is also studied. These mechanical properties can be used to distinguish between fabrics which make up into suits of good and poor appearance. The investigation of the bending properties of overfed fabrics has established an empirical relationship between the level of fabric overfeed and the natural curvature of the overfed seamed fabric composite for three different fabric configurations.

In Part 1 of this series of papers, we investigated the importance of fabric overfeed in the sewing operations during tailoring. It was also shown how fabric bending rigidity, formability, shear and hygral expansion are important in clothing manufacture. The present paper is concerned with the measurement and experimental study of seam balance, breaking elongation and bending properties of seams. The aim is to evaluate quantitatively the consumption of sewing thread and the relationship between the degree of fabric overfeed during sewing and the curvature of the seam in the garment. Balanced seams have much higher breaking elongation and more symmetrical bending properties than unbalanced seam structures. A natural curvature and curling couple result from fabric overfeed during sewing. The value of the curvature is time‐dependent because of fabric viscoelastic effect and also depends on the level of fabric overfeed, the tensile and longitudinal compressive module of the component fabrics and the structure of the seamed composite. The natural curvature of the seam may be derived quantitatively from the relative lengths of overfeed fabrics using a modified theory for a bimetallic themostatic strip.

The purpose of this paper is to mathematically model the structure of doubled fancy yarns made by combining together several threads.

It was assumed that such a structure may have two distinctive parts – sinusoidal and helical (i.e. sigmoidal). This model is based on calculating the length of the effect thread in relation to the core thread. The case of having several variants of such a structure was discussed to account for several types of doubled fancy yarns. The number of wraps of the binder, the overfed ratio, and heights of the fancy profiles in the different parts were the fundamental parameters of this model. The effects of changes in the number of wraps, the overfeed ratio or both simultaneously, on this model, were also considered. The shape factor of fancy yarn was also modelled depending on the basic model of the structure.

The model was tested and the correlation coefficient between the theoretical value and the real value of length of the effect thread was 0.90.

This model is useful for predicting the length of the effect component based on the type, dimension and number of the fancy profiles of doubled fancy yarn, and for understanding the changes of the multiple-thread structure of fancy yarn when the overfeed ratio and/or the number of wraps were to change.

The application of objective measurement of the mechanical properties of fabrics in the apparel industry began around 1975 in the Hirakata area, which is one of the centres of men's suit production in Japan. At that time the KESF system had been developed and thereafter spread rapidly. The measurement of mechanical data under low‐load level by the KESF provided useful information for the apparel engineers who needed some means of fabric measurement by which the tailoring process might be controlled. The fabric dimensional stability testing using steam press was also standardised at that time (HESC 103A method). At present, the KESF data and the stability data are essential for apparel engineers and are used widely in the Japanese apparel industry. In addition to the use of objective measurements in each factory, a centre for objective fabric inspection has been recently initiated in the Hirakata area, for the inspection and control of fabric by the objective system for tailoring process control. In addition, a co‐operative work between the apparel engineers and the university has been carried out to develop a new equation for predicting the good appearance of a suit on the basis of fabric mechanical data. Automatic tailoring such as automatic overfeed action on the basis of fabric mechanical property is also carried out under the co‐operation of the university, the apparel industry, and a sewing machine manufacturer (Juki) in Hirakata. The progress of these projects is presented.

The purpose of this paper is to define the relationships between the first spinning zone of the hollow-spindle spinning system and technological parameters of manufacturing multi-thread fancy yarn.

A simple mathematical equation was introduced to account for the effect-thread helices. The validity of this equation was tested using visual observations of the helices of the effect thread in terms of their number, width and regularity and then compared against the theoretical values.

It was found that higher overfeed ratios increased the diameter of the helices without affecting their number, while increasing the rotational speed increased their number but reduced their diameter. The effect of these changes on the fancy yarns was that higher number of helices resulted in more fancy profiles while wider helices resulted in larger fancy profiles.

This research offers fancy yarn manufacturers a better understanding of the manufacturing process of fancy yarn and its practical advantage is to help them in determining the type of the resultant fancy yarns by controlling the geometry of the first spinning zone.

Different factors affecting seam instability are discussed and major energy terms involved and their order of magnitude are recognised. By comparing pre‐buckling and post‐buckling energies, four dimensionless groups were derived which are responsible for seam instability and can be used as independent variables in analysing the experimental results. The paper goes further and compares the analytical conclusions with the results of other investigators.

The article presents the test results concerning the effect of certain of the fabric properties and the stitch length on seam puckering when some degree of overfeeding is involved. The results confirm the importance of the dimensionless groups derived in Part 1 of this article.

The goal of the research presented is to analyse seam strength properties of polyester and polyester‐polytetrafluoroethylene air‐jet textured sewing threads.

These threads are designed for sewing various garments and are manufactured by the Department of Textile Technology at Kaunas University of Technology. Manufacturing parameters are varied during air‐jet‐texturing, which includes air pressure, effect and core yarns overfeed. Tensile tests of sewing threads and seams strength tests are performed.

They indicate that the strength of seams depends on the properties of sewing threads.

Analysis of the seam strength of PES‐PTFE air‐jet‐textured sewing threads.