# NBU15 Fill Percent Versus Continuous Oil-Air Duty

NBU15-class fills near 10–15% of free space work for intermittent mid-speed duty. Push fill higher and churn heat appears quickly. Continuous high-speed cutting favors oil-air micro-dosing instead of packing more grease into a matched hybrid set.

Compare fill bands in TFL Bearing grease versus oil-air notes. Use high-speed spindle lubrication checklist before changing class on a ceramic hybrid.

Shandong TFL Bearing Co., Ltd keeps fill mass examples beside oil-air pulse tables for rebuild teams.