Connecting motion components over a long space requires multiple engineering design disciplines to manufacture a coupling that maintains smooth operation and avoids rotation through the system’s axial natural frequency (ANF). 

This Zero-Max custom CD coupling design is one of many different ones available for difficult and challenging motion system applications. The 80-inch floating shaft coupling pictured is designed around Zero-Max’s CD composite disc technology bringing to bear several engineering disciplines. This coupling design was optimized such that the operational speed (2,600 rpm) is below the ANF point. That means that the coupling will never go through the critical speed and always operate in a sub-critical speed.

Key to this design is the accurate prediction of the axial natural frequency point based on Zero-Max’s composite flex disc performance. Connecting to these custom discs are 316 stainless steel hubs passivated for extra cleanliness required for the application. A three-inch diameter 80-inch long thin-walled alloy tube connects the two coupling assemblies at each end for mounting in the motion system.

The engineering disciplines Zero-Max applied to this and many other custom coupling applications include: metallurgy and alloy material design, composite disc formation, disc deflection control, precision fastening of components and dynamic coupling balancing. These engineering disciplines required precise control of tube stiffness, stiffness properties of the composite disc and overall weight of the coupling assembly. 

(Note: Often a custom coupling can be designed so that the ANF point is above the particular application’s maximum speed. When this is not possible and the desired operational speed exceeds the ANF band, it is possible to design the coupling so that the ANF band will be within a speed range not critical for that application. The motion system operator simply programs his system to run through the ANF band to the desired operating rpm range. This ensures smooth and consistent performance where needed.)