A flexible coupling is often selected because it can tolerate some misalignment. The important word is “some.” The model values are limits for a model, not a target installation condition.
Misalignment consumes elastomer capacity.
When a coupling spends its entire operating life correcting a large fixed offset, the flexible ring is already working before torque variation and vibration are added. Better base alignment leaves more margin for small movement that occurs during operation.
Check after tightening, not only before.
Machine feet, guards, piping and connected equipment can shift the final shaft positions. Measure after the assembly is secured, and check again if an elastomer shows repeated one-sided wear.
