Full definition
Breaking strength is a critical parameter in the selection and application of conveyor belts, defined as the maximum tensile force per unit width that a belt can endure before experiencing rupture. This property is expressed in Newtons per millimeter (N/mm) of the belt's width, making it essential for determining the suitability of a belt for specific operational conditions. For example, textile belts can range from EP160, which has a breaking strength of 160 N/mm and is suitable for light-duty applications, to EP3150, which can withstand up to 3,150 N/mm and is designed for heavy-duty operations. On the other hand, steel cord belts boast higher tensile strength, with ranges like ST630 to ST10000, the latter providing a remarkable 10,000 N/mm for extremely demanding applications such as mining or bulk material transport.
When selecting a conveyor belt, it's crucial that the maximum operating tension does not exceed the allowable working tension. This is calculated based on several factors including conveyor length, lift, material weight, friction, and acceleration, as per standards such as DIN 22101 and CEMA. The allowable working tension is determined by applying a safety factor to the breaking strength; typically, a ratio of 8:1 to 10:1 is used for textile belts, while steel cord belts require a lower safety factor of 6.7:1 to 8:1 due to their inherent strength. This ensures longevity and reliability in belt performance under operational stresses.
Testing procedures are standardized to ensure accuracy in assessing breaking strength. The full-width strip tensile test per ISO 283 at a rate of 100 mm/min is commonly employed to evaluate this property. It's also important to note that breaking strength can be significantly affected by splices. For instance, hot vulcanized splices can retain between 90% to 100% of the original breaking strength, while cold splices might retain only 60% to 80%, and mechanical splices typically between 50% to 70%. Understanding these nuances is vital for engineers and procurement managers when selecting the correct conveyor belt for their specific applications, ensuring both safety and efficiency in material handling.