Thread breakage

Figure 7.2 Separated seam produced in the Wear2 process showing thread breakage at multiple points after microwave exposure.

The problems that will be studied include seam pucker and seam undulation faults caused by needle penetration poor material feeding ply-shift, folds and stitch distortion inadequate stitch tension and tension balance and irregular stitch length, skipped stitches and thread breakage. Many researchers have studied methods for automatic detection of some of these problems, which will be reviewed. Future trends will also be predicted, towards the design and development of sewing machines with further sensing and control techniques to overcome the problems herein analysed. 

Thread breakage can be an annoying problem in the sewing room, although it is often quite easy to avoid. Constant thread rupture not only causes productivity loss due to the time needed to re-thread the machine in some situations, the whole seam has to be remade, and in other, the intermption of the seam is an unrepairable defect (e.g. top-stitching a shirt collar). 

As seen before, thread breakage may result from overheated needles due to thermal aggression. Also, bad-quality or worn-out needles may cause problems due to excessive friction. Very often the problem lies in the machine. Incorrect threading or defects in the machine thread guides cause the thread to weaken and faU. The correct setting of the synchronisation and distance between needles and loopers, or other stitch formation elements, are also important. 

Thread breakage is more likely to occur at high speeds and when using higher thread tensions. Reducing these two factors certainly minimises the problem, but due to productivity or functional requirements it cannot always be done. 

Most often, the problem resides on the quality of the sewing threads. The appeal to save on thread costs does not normally pay off. The cost on thread in a garment typically does not exceed a few percent of the total price. Productivity loss due to thread breakage, besides non-repairable defects, is potentially more costly. Moreover, a good-quality thread is an asset for strong, stable and durable seams. 

Thread breakage Incorrect threading of the sewing machine Proper selection of quality threads (with good... 

Considerations and measurements of interfacial tension between polymer melts dates to the 1960s and 1970s [54 to 57]. Several different methods have been used to measure interfacial tension. Extensive use has been made of 1) the shape of drops emerging from a capillary into a second phase (falling drop) [56 to 60] and 2) thread breakage, the breakup of stationary hlaments in a second liquid phase by a capillary instability [59 to 61 ]. The latter analysis is based on the work of Tomotika [62]. Other methods have been used. 

A systematic investigation of experimental intrusion-extrusion and entrapment has also been carried out on four well characterised rigid mesoporous and macroporous solids, with either unl-and bimodal pore size distributions. In addition, the mechanism of thread breakage in single 15 wm glass capillaries has been studied. 

In complementary experiments a "macro capillary, id-15 um width, length 20 mm was designed to fit into one of the ports of the porosimeter for visual observation of intrusion, extrusion, and entrapment via thread breakage at pressures up to 200 kN/m. ... 

These are required to make threads, i.e. the final drawing, twisting and winding of cotton. Such motors must possess very smooth acceleration to eliminate breakage of threads. They are recommended to have a starting torque of 150-200% of T, and a pull-out torque of 200-275% of with a mean acceleration torque ol 150-175%. A normal acceleration time of 5-10 seconds is recommended. Faster acceleration may cause more breakages, while a slower acceleration may result in snarls and knots in the yarn as a result of insufficient tension. 

It s easy to stretch a layer of dried white glue until it splits in half, and it s easy to yank a single strand of sewing thread into two pieces. Combine the glue with many strands of thread, however, and the resulting composite is most resistant to breakage—but only in the directions parallel to the threads. Make this composite and test its strength. 

The importance of frictional properties largely exceeds the area of domestic fabric softeners. They are also key in the textile industry, as they condition the slipping of fibers over each other in all mechanical processes [20], Friction causes breakage of threads and generates static electricity. More generally, softened fabrics are pressed and sewed more easily, as there is less resistance to the metal movement. They also relax more quickly at the dry state since fibers slide over one another more easily. However, it is more difficult to cut fabrics with scissors as the blade slips over the fibers and fewer fibers are tom during cutting [20],... 

Generally speaking, denser embroidery is preferred, as it reduces potential physical discontinuities in the textile surfaces. Concurrently, conductivity is increased. However, in practice, denser embroidery is more challenging to carry out and may result in sewing needle breakage. Therefore, the embroidery density is optimized to achieve a compromise between high-quality embroidery and feasible fabrication. As shown in Table 10.2, a low loss of 0.2 dB in insertion loss was observed at 3 GHz for a 664-thread E-fiber TL (sample E) when the embroidery density increased from 1.6... 

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