The strength of high-strength nylon industrial yarn is not low. Then why does it always break during sewing? 

high-strength nylon industrial yarns are widely used in areas such as seat belts, sewing threads, fishing nets, and cordage due to their excellent wear resistance, fatigue resistance, and breaking strength. However, in actual use, some customers may encounter a puzzling issue: the test results show that the strength is up to standard, but the threads frequently break during high-speed sewing. The problem often lies in the surface smoothness and knot strength rather than the simple breaking strength alone. Below, we will help you clarify the selection思路from two perspectives. 

1. Surface Finish: The "Hidden Killer" of High-Speed Sewing Thread Breakage 

When nylon industrial yarn is used for sewing threads or weaving, high-speed friction is a common occurrence. Yarns with insufficient surface smoothness are prone to produce fuzz when passing through the needle eye or warp yarn at high speed, which can eventually lead to thread breakage. 

The relationship between lint and broken threads: The cross-section and surface condition of nylon threads directly affect their friction coefficient with metal components. If the thread surface is rough or has lint, the friction force will significantly increase during high-speed sewing, causing local overheating or even melting, which can lead to thread breakage. When purchasing, you can take a section of the yarn, hold it with your fingers and slide it quickly to feel if the surface is smooth and if there are any burrs. 

Oil agent and lubricity: The oil agent on the surface of nylon industrial yarn not only reduces friction but also has an anti-static effect. If the oil agent content is too low, the friction during sewing will increase; if the content is too high, it may contaminate the sewing equipment or affect the subsequent heat setting. When purchasing, you can inquire whether the supplier has optimized the type and content of the oil agent for high-speed sewing. 

II. Knot Strength: The strength at the knot is the "real deal" 

Nylon industrial yarns almost always form knots during sewing, bundling or rope net weaving. No matter how high the direct tensile strength is, the remaining strength after knotting is the "effective strength" that is actually used in practice. 

Tensile strength loss: After nylon filaments are knotted, due to the stress concentrating at the bent part, the strength usually suffers significant loss. The lower the loss rate, the better the flexibility and anti-bending fatigue performance of the filament. When purchasing, one can request the supplier to provide comparison data of direct drawing strength and knot strength for filaments of the same specification. 

Flexibility assessment: Nylon filaments with good flexibility are more likely to evenly tighten when knotted, reducing local stress concentration and thereby enhancing the strength of the knot. Request samples before purchasing, and conduct manual tensile tests under the actual knotting method you use to feel the force at the knotting point. Shengjie Heili Chemical Fiber Co., Ltd. in Changzhou has over 22 years of experience in the chemical fiber industry and its products are widely used in the automotive, textile, construction, sports and other industries. 

Summary and Selection Suggestions 

When purchasing high-strength nylon industrial yarn, it is recommended to confirm the following steps: 

Evaluate surface finish: Request samples and feel the surface with your hands to check if it is smooth and free of burrs. For high-speed sewing, you may ask the supplier to provide data on oil content and dynamic friction coefficient tests. 

Pay attention to the strength of the knots: The supplier is required to provide data on the knot strength or the rate of strength loss, and conduct manual tests based on your actual knotting method. 

Sample machine trial: Conduct a small-scale trial on your own high-speed sewing machine or loom to assess the actual usage effect. 

Changzhou Shengjie Heuli Chemical Fibers Co., Ltd. has over 22 years of experience in the chemical fiber industry. It specializes in high-strength polyester industrial yarn, high-strength nylon industrial yarn, high-strength polypropylene industrial yarn, polyester flame-retardant yarn, polypropylene flame-retardant yarn, polyester FDY yarn, and variable-width yarn, etc. Please feel free to send samples for testing and communicate your specific requirements. 

Official website: http://www.sjfibre.com