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Key Differences between Residual Balancing (ISO) and Potential Balancing (AGMA)
Any coupling can be residually balanced. Because of this, most manufacturers just residually balance everything. This allows them to make loose tolerance low, cost parts then just correct the imbalance. The big problem with this is the lack of part interchangeability. Once you drive down the residual imbalance of a coupling assembly, it is now a unit that cannot be switched and swapped with other spare parts. This can make proper coupling maintenance a real headache as well as costly. A true AGMA coupling has completely interchangeable components. This means all parts are manufactured with tight geometric tolerances to insure the center of mass is as close to the center of rotation as possible.

Specifying a Coupling Balance
Prior to ordering an AGMA Class coupling, make sure to ask for the balancing calculations. This is a simple root mean square analysis of the manufacturing tolerances. This analysis determines whether or not the coupling is actually AGMA Class compliant.

As an example, a great step to insure a true AGMA Class 9 rated coupling is being supplied is to ask for a barrel to bore run out of 0.002″ or outer flange to Bore run-out of 0.002″. This simple request will instantly tell if you are really receiving a true AGMA Class 9 coupling.

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