Machine Technology: Latest in lubrication

Want a good reason for lubricating the moving parts of machine tools? Here’s one from Klüber Lubrication NA LP, Londonderry, N.H., a developer of specialty lubricants: Lubrication of machine tool components minimizes wear.

“When a component in a machining center wears—whether it’s a spindle bearing, a ball-screw, a gear or whatever—you start to lose precision,” said Steve Mazzola, Klüber’s director of engineering. “And when you lose precision in a machining center, you may produce parts that are out of spec.”

Precise machining depends in part on proper lubrication of moving components. All images courtesy Klüber Lubrication.

A more-serious possibility is catastrophic failure caused by wear. Mazzola pointed out that even small amounts of wear can cause high-speed spindle bearings to fail. “That’s why lubrication of those spindle bearings is the lifeblood of the machine tool,” he said.

Among the more-recent developments in machine lubrication is the increased attention given to the cleanliness of oil applied to lubricate spindles. This is important, Mazzola said, because small amounts of dust, dirt and other
debris in lubricating oil can have a big impact on high-speed spindle bearings, causing wear that may result in catastrophic failure, as well as unwanted noise.

In response to the threat posed by contaminants, Mazzola noted that lubrication manufacturers have developed high-purity oils, and the International Organization for Standardization has established a standard to quantify the cleanliness levels of lubricating oils. In addition, efforts have been made to educate end users about proper storage and application of oils to reduce oil contamination in plant settings.

Machine tool users have also benefitted from the introduction of greases for higher-speed applications. “It used to be that for low speeds you used grease and for high speeds you used oil,” Mazzola said. “But now greases have been pushed to extremely high speeds.”

This is beneficial, Mazzola explained, because greased components are often considered “lubricated for life,” while oiled components require relubrication over their normal service lives. Components commonly thought of as lubricated for life include grease-lubricated spindle bearings, which normally achieve 3 to 5 years of “fairly continuous service,” he said.