Whether brand new from the factory OEM or just repaired at a local repair shop, rotor balance plays a critical role in motor life. Unfortunately, there's a great deal of variation in the practice of rotor balancing and many motors are failing prematurely as a result. Rotor imbalance creates force on the bearing assembly, resulting in vibration and heat. And smaller imbalances have a cumulative effect over time, stressing lubrication and the bearings. Studies show that decreasing vibration from 0.4 inches per second to 0.2 inches per second will almost double bearing life. There are two standards often referenced for balancing, NEMA and ISO. ISO-1940 standard corrects imbalance and units of actual force on the bearings and provides superior results. ISO also provides balancing guidelines and what is referred to as the G scale. A rotor balanced to G2.5, for example, will vibrate at 2.5 mm per second while rotating at rated speed and suspending on a free standing mount. Most repair shops provide balancing as a standard service, but not all of them correctly apply the ISO standard as it is more complex. And many still use the NEMA standard, which is the default in most commercially available balancing machines. So how do you know if you're buying the best possible balance and ensuring the longest possible run life? First, take a look at the repair report provided by your shop. You should see the recorded RPM, rotor weight and imbalance force clearly label. Second, visit your shops and take a look for yourself. You can quickly and easily inspect for a certificate of the balance machine by an ISO-qualified lab, a certificate of calibration to ISO-1940. A convenient means of weighing rotors, shaft stops to control movement while not introducing force into the assembly during the test, and a written balancing procedure referencing the ISO-1940 standard. To learn more about this or other services we offer, visit us at ecoonline.com.