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TECH BRIEFS productionmachining.com :: 29 "In such instances, it's advisable to reach out to OEM resources—the bearing suppliers, for example—to provide another level of failure analysis," Mr. Kirkpatrick says. "Suppliers that provide tooling drawbar systems and other third-party experts can also be called upon to complement the failure analysis effort by substantiating report findings as they pertain to their products." When customers experience repeated failures, Mr. Kirkpatrick advises that a spindle specialist visit the customer's production line to get a firsthand view of the CNC center on which the spindle is running. When techni- cians perform on-site inspection, problems not pertaining specifically to the spindle itself may be discovered. For example, one of Superior Spindle Service's major automo- tive customers was experiencing repeated failures, which had caused considerable downtime, as well as more than $120,000 in spindle service costs. "Each time we inspected one of the customer's wrecked spindles, we determined the most likely cause was a bearing problem related to a malfunction of the spindle's air supply," he explains. "Although we suggested in each failure analysis report that the customer re-check the air supply, each time they checked, the air supply seemed fine. So, our technician inspected the air supply pressure gage and found that the gage needle was stuck, and the air wasn't turned on. So we installed a new gage, and the customer hasn't experienced a spindle problem for more than two years." Other on-site visits have revealed setup and alignment problems, improper spindle mounting, motor-related problems and controller malfunctions. Mr. Kirkpatrick is convinced that intensive failure analysis can lead to extended spindle service life. For example, when customers are working with softer metals, decreasing spindle rpm and increasing feed rates can increase spindle life with no impact on cycle times, he says. In another instance, one of his customers was chronically burning bearings from running a spindle continuously at high speed. So, the spindle technician recom- mended a different bearing setup, and the spindle service life improved dramatically. Superior Spindle Service has an inspection center that is dedicated to spindle motor electronics. is includes motor mega-ohm value, thermistor value, encoders, motor proximity sensors, and analog sensors. "We not only bench check the motor, but we confirm that it communicates accurately with whatever type of machine controller the customer has installed at their CNC machine," says Mike Davis, who manages the center. "During this process, we also determine motor life expec- tancy and can predict the failure mode. is enables us to suggest that the customer have the motor rewound or baked, in order to avoid potential failures." Mr. Kirkpatrick believes that, when a spindle is under- performing in a specific application, it is possible to improve performance through spindle design modifica- tions such as spindle metallurgy or shape. rough the use of air gaging equipment, the company is capable of detecting when a customer's spindle taper is out of OEM specification and can help return the taper to the proper spec within 50 millionths of an inch. However, if a somewhat modified taper will improve performance for the customer's specific application, the air gage equip- ment can precisely verify the geometry of that modification as well. For more information from Superior Spindle Service LLC, call 877-946-7400 or visit superiorspindle.com. Find related articles by visiting PM's Single-Spindle Screw Machine Zone. LINK :: short.productionmachining.com/spindles :: Every step of the spindle repair process is photographed and documented, and a comprehensive failure analysis report is provided, along with recommendations related to proper operation and the value of predictive maintenance.