Sewability

Optimal sewability is achieved through the interaction of the quality characteristics explained here. Due to the lack of DIN or ISO standards, AMANN tests sewability according to specially developed regulations in its own sewing and embroidery laboratories. 

Depending on the type and strength of the sewing thread, the following sewability tests are carried out:

• Reverse sewing
• Zigzag sewing
• Multidirectional sewing
• Buttonhole sewing in underwear
• Thermal sewing
• Sewing at high speeds
• Test embroidery
• Water-repellency tests
• Serging seams tests
• Crimping tests
• Fibre abrasion tests
• Abrasion tests
• Tendency to static charge
• Unwinding tests
• Fraying tests

In these sewing positions, the sewing threads are subjected to stress due to their different properties. The production of underwear buttonholes, for example, places high demands on abrasion resistance due to the short stitch length. Reverse and zigzag sewing as well as multidirectional sewing are used to test the compactness of the thread and its tendency to open. This allows the level of twist and any bonding to be assessed. Sewability depends on numerous influencing factors. In addition to the quality characteristics already listed, two further properties are important.

Low-twist sewing threads are open, which means there is a risk that the hook will hit the open thread during the stitch formation process and tear it. Sewing threads that are twisted too tightly tend to curl. Knots and loops can form and lead to sewing problems. At the same time, the ratio of yarn and thread twists to each other is important in order to obtain a compact, balanced sewing thread.

The surface structure is primarily determined by the yarn or thread construction and influences sewability. Due to their textile, fibrous surface, spun threads and core spun threads behave differently on the sewing machine than continuous filament threads, for example. Bulk yarns have different sewing properties than conventional sewing threads and, due to their voluminous nature, cannot be sewn in all sewing positions. Monofilaments are stiff and smooth, making it difficult to secure the loop formation at the ends of the seam.