What does the breaking groove on a mandrel indicate?

The breaking groove on a mandrel serves as a marker indicating the point where the mandrel is designed to break during installation. This is crucial for ensuring that the mandrel performs its function safely and effectively. When the correct amount of force is applied during the installation of a fastener, the breaking groove aids in controlling the point at which the mandrel will yield, ensuring that the installed rivet achieves the proper compression and integrity necessary for the application's structural requirements. Identifying this point helps technicians avoid over-tightening, which could lead to potential damage or failure of the assembly. Understanding the function of the breaking groove is essential for aerospace assembly mechanics to ensure quality and safety in their work.