How to test webbing strength

For any manufacturer using webbing, especially those producing pet leashes, outdoor backpacks, bag handles, or industrial tie‑downs, ensuring adequate webbing strength is fundamental to product safety and customer satisfaction. However, “webbing strength” is not a single concept; it covers tensile strength, tear resistance, abrasion resistance, and other dimensions, all of which need to be assessed through standardized and rigorous testing methods.

To accurately evaluate webbing strength, one must first understand the test standards and conditions. Internationally recognized standards such as ASTM D6775 for general textile webbing and DIN EN ISO 1421 for rubber‑ or plastic‑coated fabrics provide a unified testing framework. Before testing, the sample must be conditioned in a standard atmosphere of constant temperature and humidity (typically 23±2°C and 50±5% relative humidity for at least 24 hours) to eliminate the influence of environmental factors. The core testing equipment is a universal testing machine (UTM), which can pull the sample at a precisely controlled rate and record the force data.

The most direct way to evaluate the core mechanical properties of webbing is through tensile strength testing and elongation at break testing. Together, these tests describe how the webbing behaves under tension until it fails. During the test, a standard‑size webbing sample (e.g., 50 mm wide, about 300 mm long) is clamped in the machine and pulled at a constant speed (e.g., 500 mm/min or 50 mm/min) until it breaks. The equipment records two key values: the breaking force – the maximum load the sample can withstand before rupture – which directly determines how much load the webbing can bear in actual use. A high‑quality TPU coated webbing should have a webbing tensile strength of at least 35 MPa. The second value is elongation at break – the percentage of stretched length relative to the original length at the moment of break. This indicates the material’s ductility, i.e., how much it can deform before complete failure, which is important for evaluating shock absorption. For example, good TPU coated webbing may have an elongation at break exceeding 400%, meaning it can stretch to four times its original length before breaking. It is worth noting that standards for coated fabrics, such as ISO 1421, distinguish between the “strip method” and the “grab method”; the latter clamps only the middle part of the sample to better simulate real‑world stress distribution.

In practical applications, webbing is also subjected to shearing, cutting, or repeated friction. Therefore, tear strength testing and abrasion resistance testing are also indispensable for evaluating the quality of coated webbing. One standard method for tear strength is ASTM D5587 – the “trapezoid method”, where a trapezoidal notch is cut into the sample and then it is pulled to measure the force required to propagate the tear. This differs from pure tension and simulates how easily a rip can spread after the webbing is punctured by a sharp object – critical for safety‑related applications. Abrasion resistance can be assessed using ASTM D3884 (the Taber abrasion method), where standard grinding wheels are rotated against the sample surface under a fixed load. The number of cycles until visible wear, fraying, or breakage indicates durability. Generally, better abrasion resistance means the webbing will maintain its appearance and strength longer. For example, in abrasion tests, TPU coated webbing may show only minor wear after 100,000 cycles, while a comparable PVC product might already exhibit significant cracking after 50,000 cycles.

Besides tensile properties, hardness and adhesion are critical quality indicators specific to coated webbing. Hardness directly affects hand feel and flexibility. Measured with a Shore durometer, the recommended hardness range for TPU coated webbing is typically 80A to 85A – considered the ideal balance between support and comfort. Adhesion testing specifically assesses the bond strength between the coating and the inner fabric core. Using a 90° or 180° peel test, the force required to separate the two layers ensures that the coating does not delaminate, blister, or peel off during use, which is essential for maintaining the overall durability and waterproofness of the coated webbing.

Finally, evaluating webbing strength also requires considering its long‑term performance in real environments. Static or dynamic load testing simulates prolonged loading or repeated stress. A static load test applies a constant weight to the webbing and observes whether it exhibits excessive creep or breaks over time. For equipment that experiences intermittent, repeated impacts – such as climbing slings or pet leashes – dynamic load testing is more critical. It applies cyclic loading to simulate the fatigue stress the product will encounter over its lifetime. Additionally, weathering tests that expose webbing to UV, high humidity, and high temperatures are essential to assess how well it retains its strength under harsh conditions.