Keyed connections are among the most proven and widely used solutions for shaft–hub connections. They combine high functional reliability with exceptional ease of assembly and disassembly—qualities that have made them a standard in drive technology for decades. The design of torque transmission is based on the permissible surface pressure according to DIN 6892 [1], while fatigue strength is determined following the established methodology of DIN 743 [2], taking into account notch sensitivity factors β.
Recent experimental investigations under torsional loading [3] have compellingly demonstrated that the common assumption, “The higher the strength of the shaft material, the higher the strength of the connection,” does not always hold true. The reason lies in fretting fatigue—a damage mechanism that significantly affects high-strength material combinations such as 42CrMo4+QT and 18CrNiMo7-6E. The findings have made it possible to precisely recalibrate the previously applied notch sensitivity factors, thereby substantially increasing design reliability for this connection technology.
As a result, robust data and optimized design parameters are now available, enabling keyed joints to be applied not only in conventional but also in highly dynamic applications—reliably and cost-effectively.
[1] „DIN 6892, Mitnehmerverbindungen ohne Anzug – Passfedern – Berechnung und Gestaltung“. Beuth Verlag, 2012.
[2] „DIN 743, Tragfähigkeitsberechnung von Achsen und Wellen“. Beuth Verlag GmbH, 2012.
[3] F. Kresinsky, A. Hasse, und E. Leidich, „Gestaltfestigkeit dynamsich rein torsionsbeanspruchter Passfederverbindungen“, AiF, 20055, 2021.