Needles threading

Delicate forceps, needles, thread, scissors, and safety pins. 

This stitch formation is also called bottom cover , and is made with two needle threads and one looper thread with the looper thread passing across the underside of the seam to give cover (Figures 6.26 and 6.27). Each needle thread passes initially... 

This stitch formation consists of one needle thread and two looper threads with the looper threads forming a purl on the edge of the fabric (Figure 6.28). The needle thread provides the seam strength and the looper threads provide cover on the edge of the fabric that prevents frayed edges and creates a neat appearance on the seam. 

A variety of stitch types can be disassembled using this technology. Stitched joints snch as 301 lockstitch require the microwave-triggered thread to be present only in one section of the stitch stfucture. This means only the upper bobbin thread or upper needle thread needs to be made from the miCTowave-triggered thread to enable disassembly (Figure 7.3). 

Chain stitches are formed using one or more needle thread(s) and are characterized by intralooping. One or more loops of thread are passed through the material and secured... 

Type 103 is formed with one thread and a curved needle that passes from the left to the right, entering and exiting from the same side of the material carrying a needle thread that is intercepted by a bhnd looper (Figure 10.6). It can be used for hemming, belt loops, and felling operations. 

The lockstitch class 300 is the most commonly used, as a complete garment can be sewn on a lockstitch machine. These stitches are formed by a needle thread or threads, introduced from one side of the material, interlacing with an under-thread supplied from a bobbin on the other side. 

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. 

Type 402, the cording stitch, is used ptimarily for stitching permanent creases. It uses two needle threads that produce two parallel rows of stitching on the face of the fabric. A looper thread travels between the two needle threads on the back of the fabric, creating a ridge or crease between the needle threads on the face. Type 402 is used on sportswear where a crease needs to be maintained e.g. at the back of gloves. 

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). 

Figure 12.7 Correctly balanced overedge stitch type 504. Left Schematic representation. (UL, upper looper thread LL, lower looper thread N, needle thread). Right Reahstic representation.

When the needle thread loop is too loose, the joined fabric phes are not adequately held together, which may be acceptable in some situations (serging seams) and unacceptable in others (joining seams). If any of the interlacing spots of the threads do not match the pre-defined positions, there is an imbalance between the thread tensions. This will normally influence the seam s performance negatively, and should thus be avoided. 

Figure 12.10 Needle thread-force waveforms on an industrial over-edge sewing machine over five stitch cycles, with occurrence of a skipped stitch in the fourth cycle. 

Alagha, M.J., Amirbayat, J., Porat, L, 1996. A study of positive needle thread feed during chainstitch sewing. J. Textile Inst. 87 (Part 1, No. 2), 389—395. 

III hold the upper thread (needle thread) while lowering and raising the needle one time to loop the upper thread around the lower thread (hohhin thread). 

Gripper Taking of the thread loop of the needle thread and interlacing this thread... 

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