How is shaft vibration and couplings misalignment related?

Edited by Mike Santora

If you design a machine and fail to notice there is significant shaft vibration you end up feeling it—both literally and financially.  Misaglignment leads to shaft vibration, which can subject the driven shaft of your motion system to load increases, which leads to components bending, which leads to…well, you get the picture.

Shaft vibration and misalignment are related as they can both be the cause of the other.  For example, a bellows type coupling when used to compensate for small misalignments, can actually impart a load back to the shafts (commonly referred to as axial or lateral spring rate), which can eventually cause vibration. Here, axial spring rate describes the force needed to move the bellows a specific distance. It is important to consider the manufacturers listed spring rate when using a bellows coupling in you design.

But don’t lay all the blame on your coupling and its inherent spring rate. Keep in mind that vibration from the motor or other parts of the machine may result in axial or angular misalignment which must be accounted for by the coupling. Both sides of the equation must be factored in.

GAM
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