Spindle maintenance pays

Every machine tool owner can reap benefits from a good spindle maintenance program. These include reductions in costly unplanned machine downtime, longer spindle life and improved part quality.

But effective spindle maintenance requires perseverance and the appropriate technology—plus a little common sense.

“We receive many calls about spindle operation and maintenance issues—the proper coolant to use, lubrication settings, etc.—and, in most cases, the answers are right in the manual,” said Gary Quirion, president of GMN USA, Bristol, Conn., which sells and repairs spindles. Quirion advises customers to read the operating manuals supplied with spindles from front to back. “They were made for a reason, and there’s a lot of good information in there.”

The main cause of spindle failure is bearing contamination. Image courtesy GTI Spindle Technology.

Quirion also recommends training operators to spot telltale signs of spindle problems. “Even without sophisticated vibration-analysis equipment, machine operators can be the first line of defense against failure,” he said. Warnings that something might be wrong include a change in spindle sound, an increase in operating temperature and the inability to hold part sizes within required tolerances.

Inspections are also crucial to properly maintain a spindle, noted Tom Hoenig, president of GTI Spindle Technology Inc., Manchester, N.H., which provides spindle repair, rebuilding and predictive maintenance services. For example, Hoenig said spindle lubrication and the coolant chiller for the spindle should be checked at least weekly. He also recommends regular inspection of the drawbar, which clamps a toolholder to the spindle, because the drawbar is a high-wear item that can destroy a spindle if not maintained.

Of course, the main objective of a spindle maintenance program should be to prevent spindle failure. “Wearing out a spindle is one thing, but when a spindle fails catastrophically, especially a high-speed spindle, a lot of other components can get damaged,” Quirion said.

GTI touts vibration analysis as the best method for detecting potential failure modes. According to the company, vibration-analysis tools detect imbalance, looseness and bearing problems so a spindle can be removed before an incident necessitates costly component replacement or rework.