Tensile Testing
The breaking force is the load at which a chain fails due to fracture under quasi-static (very slow) load increase. Usually, failure occurs at the smallest component cross-sections, typically with an inner link breaking at the pin eye or a pin shearing off.
The ISO 606 standard for roller chains specifies minimum breaking forces for all standard chain types. iwis chains exhibit significantly higher breaking forces compared to the standard — a quality feature that provides designers and users with increased safety potential. Alongside wear resistance and fatigue strength, breaking force is one of the most important quality characteristics of a chain.
Breaking Force Determination
The determination of the breaking force is usually carried out by vertically clamping a test specimen in a universal testing machine and gradually increasing the load until the chain fails due to excessive tensile stress.
In the design and dimensioning of chain drives, the fatigue strength of the chain is decisive in most cases. Therefore, as a rule of thumb, it is recommended to calculate with a safety factor of 7 based on the breaking force.
