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This paper aims to develop a single regression model (instead of developing models separately for each thread type) to predict the sewing thread consumption for cotton and polyester staple spun threads.

A single regression model is developed for predicting sewing thread consumption for cotton and polyester threads. The polyester sewing threads have lower sewing thread consumption as compared to cotton threads because of their higher elongation behaviour. The model differentiates between the cotton and polyester sewing threads using their elongation values at peak levels of tensions experienced by the sewing threads during stitch tightening. By comparing the estimated thread consumption values with actual values, the effectiveness of model is evaluated with root mean square error and coefficient of determination (R²).

During the sewing process, by understanding the behaviour of different types of sewing threads, it is possible to develop a single regression model for all types of threads.

The sewing thread consumption can be easily calculated for cotton and polyester sewing threads using a single regression equation using the sewing assembly thickness, stitch density and elongation of thread at peak tension. The garment manufacturers need not depend on different charts for sewing thread consumption for stock management.

The sewing thread consumption is different for different types of threads, and garment manufacturers have to depend on different charts given by sewing thread manufacturers or use different equations for each type of threads. Using this single regression equation, sewing thread consumption for cotton and polyester sewing thread can be estimated accurately.

In this paper, the contribution of dynamic loading, needle and fabric, and the bobbin thread interaction on the changes in the tensile properties of the needle thread are to be investigated.

Tensile properties of the needle thread have been studied at four sewing stages, namely before being subjected to any loading, after dynamic loading, before bobbin thread interaction and after sewing.

It is observed that bobbin thread interaction plays a dominant role in the reduction of tensile properties except breaking elongation in cotton threads. Dynamic loading is mainly responsible for reduction in the breaking elongation of cotton threads. During sewing, there is an increase in initial modulus due to the dynamic loading, which is more in the case of cotton threads than polyester threads. However, the impact of dynamic loading on tenacity, breaking elongation and breaking energy is greater for coarser cotton thread. The contribution of bobbin thread interaction is more for fine threads as compared to coarse threads.

Since seam strength is dependent on the thread strength, a reduction in thread strength during sewing will lead to lower seam strength than expected. Therefore, in order to minimize the thread strength reduction, it is important to understand the contribution of different machine elements or processes during sewing. During high‐speed sewing, the dynamic and thermal loading are found to be the major causes of strength reduction of needle thread, which can go up to 30‐40 per cent. However, the extent of strength loss at different sewing stages is unknown.

The study will help in engineering sewing threads, designing of sewing machines and selection of process parameters for controlling loss of useful properties of sewing threads.

The paper aims to evaluate the influence of mechanical properties of sewing threads on the seam pucker.

The mechanical properties of sewing thread were obtained performing tensile testing research. The seam pucker of lightweight fabric was evaluated after sewing, then after 24 h, after 48 h as well as after washing and drying. To determine dimension changes of fabric, the relaxation shrinkage was calculated. The results of thread properties and seam pucker were compared.

In respect of seam pucker the best results were established sewing with polyester threads, the reversible strain of which were the least. After washing and drying, the highest pucker was typical of the specimens sewn with cotton sewing threads. It was noticed that increasing the amount of layers in sewing the influence of threads on seam pucker decreases. Washing and drying made considerably greater influence on the occurrence of pucker then time.

This study has practical implications in the clothing and other nearly related industries. In the paper recommendations involved with application of sewing thread and evaluation of seam pucker are presented.

In most cases the changes of sewn thread mechanical properties after sewing is analysed. This study is aimed to determine the influence of thread properties on seam pucker. Recommendations in the area of sewing thread and garment quality are based on the research.

Denim fabrics of various weight ranges were sewn with three different compositions of sewing threads ‐ 100 per cent cotton, 100 per cent polyester and corespun thread ‐ with all possible ticket numbers, to examine the interaction of various fabric‐thread combinations. The sewing thread performance in terms of seam efficiency, pucker, slippage and needle cutting index was determined and the results were analysed in the light of the dimensional and mechanical properties of the fabric, thread and seam itself. Corespun threads were found to be most suitable from a seam efficiency point of view. However, other sewing parameters such as pucker, slippage and damage were adversely affected by sewing with corespun threads. Tensile properties of fabrics and threads were found to be the most important factors for sewability. Breaking strength and elongation of the fabric and sewing thread had an excellent correlation with seam efficiency. Cotton threads were found to be most suitable for sewing denim from a seam puckering point of view. On the other hand, polyester threads were more prone to develop seam pucker. Corespun thread was the greatest yarn damager compared to cotton and polyester threads. Fabric cover factor and sewing thread diameter were highly correlated with the needle cutting index.

The viscoelastic properties of the sewing thread before and after loading in the sewing process were investigated. Sewing threads are subjected to dynamic tension and friction in the sewing process. In order to compare polyester, cotton and silk sewing threads, the fineness of the threads were selected to be almost equal. There are some differences between the stress extension curves of the parent thread and the sewn thread except for the polyester sewing thread. The phenomenon of inverse relaxation occurs for high levels of retraction. The stress‐inverse relaxation index for the polyester sewing thread is larger than for other threads and the inverse relaxation for silk thread is small. From the creep curves, the sewn threads show higher secondary creep and lower instantaneous recovery than the parent threads.

The mechanism of strength reduction of sewing threads has been discussed in Part I of this paper. The effect of fabric tightness and certain thread properties like its size, coefficient of yarn‐metal friction, twist direction, number of piles, type of fibre and fibre denier on strength reduction has been studied and found to influence the severity of strength reduction of the thread.

Simulating the behavior of clothing has always been of interest in the apparel, fashion and computer game industries. With the development of these industries, there is a need to increase the accuracy of clothing simulation techniques. A garment contains many seams whose behavior affects its final appearance. In this study, a numerical model is presented to simulate seam puckers in single- and double-layer fabrics.

A yarn-level simulation technique has been used for this purpose. Based on this technique, the individual threads in the fabric structure and the sewing threads are modeled separately. Then, their behavior and interaction with each other are considered in the seam pucker model.

The model is used to simulate the real samples. The results show that the proposed model is able to simulate the degree of seam puckering for a single-layer fabric with an average error of 7.9% and for a double-layer fabric with an average error of 8.5%.

The behavior of the seam is affected by the properties, behavior and interaction of the sewing threads and yarns in the fabric structure. In previous studies, the parameters related to seams and fabrics were not fully considered. In this study, a new yarn-level model is presented to simulate seam puckering in woven fabrics. The most important advantage of this type of simulation is the ability to examine the interaction of fabric threads as well as the interaction of sewing threads with each other and with the threads of the fabric structure.

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.

Durability of textile materials under wet conditions has become very important in recent years. The water repellency performance of fabrics should be maintained in the seam areas. The purpose of this paper is to analyze the effect of water repellent agents and sewing threads on the seam and water repellency performance properties of woven fabrics.

100 percent polyester woven fabrics were treated with three different water repellent finishing agents (silicone, fluorocarbons with 6 and 8 carbons) and then sewn with different sewing threads (unfinished/water repellent finished polyester/cotton corespun and polyamide filament). Afterwards, mechanical properties, seam performance and water repellency properties of these materials were measured.

The effect of finishing which was statistically significant on seam strength only in warp direction was significant on seam elongation and efficiency in both warp and weft directions. Seam strength, seam efficiency, seam slippage and seam pucker of fabrics sewn with polyamide threads were higher than others. The fluorocarbons applied to the fabrics gave higher water repellency values than silicones. In addition, as the chain length increased in fluorocarbons, water repellency performance increased. Sewing process reduced water resistance of fabrics; however, water repellent finish applied to the threads increased water resistance of fabrics.

As a result of the literature review, it was seen that water repellency property of a wear were studied in only seamless areas of fabrics. Originality of this study is that the water repellency properties are also analyzed in the seam areas of the fabrics and evaluated together with the seam performance characteristics.

The conversion of fabric into a garment involves many interactions such as the selection of suitable sewing thread, optimization of sewing parameters, ease of conversion of fabric into the garment and actual performance of the sewn fabric during wear of the garment. The adjustment of all sewing parameters is necessary to ensure quality. The purpose of this paper is to define the parameters that affect seam quality comprehensively.

This study primarily focuses on the studies dealing with the effect of various parameters on-seam quality in detail. A systematic literature review was conducted.

The interactions between parameters may lead to different results than the effect of a single parameter. In addition, changing some parameters may have a positive effect on one element of seam quality while having a negative effect on another. For this reason, it is very important to properly select the parameters according to the specific end use of the garment products and also to consider the interactions.

The knowledge of various factors that affect seam quality will be helpful for manufacturers to improve production performance and to be able to produce high-quality seam.