Stitches seam types

Seam types used for woven fabrics include superimposed seams and double-lapped seams, especially when a high degree of strength is required, for example, in judo suits. Hemmed seams are also used on legs, and a lockstitch is used on areas that include labels and pockets. Sewing threads would be mainly staple core-spun polyester. Round-point needles are used for stitching these materials. 

Types 515, 516 and 519 are a combination of an over-edge stitch and a 401 chain stitch. This type is called a safety stitch (the chain stitch closest to the seam is backed by a row of another tight over-edge stitches), and is used in manufacturing shirts, jackets, blouses and jeans. Figure 10.17 shows stitch types 515 and 516. 

The most comphcated stitch type in this class is type 606, known as flat lock, which can be used to join fabrics that are butted together in what used to be called a flat seam. Type 606 is used on knitted fabrics, especially underwear fabrics. 

BS 3870-2 1991, Stitches and Seams. Classification and Terminology of Seam Types. 

The book Stitches and Seams (Laing and Webster, 1998) provides a detailed analysis of the fundamentals of different types of stitches, seams and sewing threads explains how they are produced and examines their optimum design, performance and modes of failure. 

On the website of American F.fird (www.com/technical-tools/stitches-and-seams/ amefird), there are good instructions for use of stitches and seam types and SPl recommendations for wovens and knits, because using the correct number of SPl can greatly enhance the strength, appearance and performance of the seam for a given fabric type and application. 

Structural seams. The purpose of this seam type is to stitch the elements, which transmit the forces between various semi-finished goods or layers via tailored reinforcements e.g., ribs on support structures). These seams can also be used for positioning inserts or to enhance connections of inserts to the entire structure. Joining seams penetrate through the complete preform and are stitched by using threads made of carbon or glass fibers. 

Similar stitch types Different seam types... 

Many types of seams can be constmcted in ways involving different raw materials, stitch types and machinery. An optimum combination of these, along with minimised thread consumption, will provide an economical approach to manufacturing. 

This stitch formation has a row of stitch type 504 plus and extra row of stitch type 401 as described above. This stitch is produced on one machine and has a dual role of providing neatness on the edge with the 504 stitch whilst at the same time providing great strength to the seam with the two-thread chainstitch 401. An example of this stitch and its appearance on the seam is given in Figure 6.29. 

An example of a garment assembly page of a tech-pack is shown in Figure 2.7. This page includes the sequence of assembly operations along with the stitch count (stitches per inch), seam and stitch notations, machine type for each operation, and any special instmctions assisting the apparel production. The component sketch area shows the components that are available for assembly. 

The strength of the seam should be equal to that of the material it joins in order to have a balanced construction that will withstand the forces encountered during use (Nayak et al., 2010). The transverse strength of a seam is determined by a number of factors, such as stitch type, stitch density, thread strength, thread tension, needle size, and needle type. It will be observed that the seam failure in a garment can occur because of ... 

In order to visualize the development of pucker, a model (Figure 3.3(a) and (b)) is shown to understand the deformation of fabric stmcmre due to the insertion of a seam in it. This stitching line or a seam has to find a position on and in the plane of the fabric. In order to accommodate the bulk of stitch, the fabric yam in both directions gets displaced around this juncture. Depending on the physical and mechanical properties of the fabric, the sewing thread may have no resistance from the fabric and would manifest in different types of yam movements (distortions) in the fabric structure otherwise due to resistance from the fabric, only compression of the thread and fabric yam may take place. The former causes severe pucker and the latter causes little or no pucker. It is either the yams parallel to the seam, or the ones perpendicular to the seam, that absorb the longitudinal and lateral... 

An increase in the values of these factors increases the fabric resistance to seam slippage. Seam slippage depends on weave, fabric raw material, type of seam, stitch density, and sewing thread tension. 

When a tensile load is applied to a fabric seam, it has to overcome two types of frictional forces. One is the inter-yam frictional forces within a fabric, and the other is the frictional force of the stitch assembly. The former is dependent upon the crimp, yam diameter, fiber content, and number of cross-over points. The latter, however, is dependent upon the fabric properties like fiber content, type of yam (spun or filament), thickness, lateral compression, cover factor (threads per cm), bending, shear, tensile and surface roughness, and coefficient of friction. It is also dependent upon the properties of the sewing thread like fiber content, diameter, coefficiait of Mction, initial modulus, and extensibility. All of these properties, together with the machine variables like needle and bobbin thread tension and the stitch length, make up the frictional force of the stitch assembly. Thus different combinations of these would be expected to provide different frictional resistance and hence different loads at which seam slippage may take place. 

Applications of lock stitches include seaming operations on all types of garments and run stitching. Lock stitch is extensively used for joining fabrics collar, cuff, pocket, sleeve, facing etc. Lockstitch type 301 is the simplest, which is shaped from the needle thread and the bobbin thread (Figure 10.9). 

Stitches in this class are sometimes referred to as double-locked stitches, because the needle thread is interconnected with two loops of the under-thread. Applications of multi-thread chain stitches are seaming operations on all types of garments. 

The most common stitch types in this class are type 401, 402, 404, 406 and 407. Type 401, or the two-thread chain stitch, has the appearance of a lockstitch in the top but has a double-chain effect formed by a looper thread on the underside. The chain generally lies on the under surface of the material, with the needle thread being drawn through to balance the stitch. The loop formation of the chain stitch elongates when extended thus it is used for seams that require elasticity, such as setting sleeves and attaching elastic materials. Stitch type 401 is shown in Figure 10.13. 

Stitch types 512 and 514 are also called mock-safety stitches. These are four-thread over-edge stitches that are formed with two needle threads and two looper threads. Type 514 is stronger and more elastic than 512, but both may be used for seaming knits and wovens (Figure 10.16). 

Cover stitches 602 and 605 are very strong and elastic stitches. Stitch type 602 is formed with four threads (two needle threads, one looper thread and one topcovering thread) and used for covering stitch or seaming knit. Class 605 is a similar stitch but formed with three needle threads, one looper thread and one top-covering thread. This class is used for covering stitches or butt-seams. Figure 10.19 shows stitch types 602 and 605. 

The flat-seaming stitch type 607 with nine threads (four needle threads, four looper threads and one top-covering thread) is used for trims and seams simultaneously, producing the flat, butted seams as on infant panties, men s briefs and other knitted garments (Figure 10.20). 

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