We often hear “Coupling alignment tolerances provided by the coupling manufacturer are good enough for shaft alignment.” or “There’s no need to align your machines tighter than the tolerances allowed by your flexible coupling.”
This is wrong because good quality flexible couplings may be built to withstand much more misalignment than what is good for your connected machines, in terms of the vibration and other forces created. Bearings and seals may wear out and fail faster than a highly misalignment-tolerant coupling. The reason for this “extra misalignment capacity” in flex couplings is that they may need to withstand significant positional changes resulting from thermal growth or dynamic load shifts. This lets you deliberately misalign machines to “cold alignment” targets.
Take a look at our Shaft Alignment Tools