20000RPM High Speed Angular Contact Ball Bearing 71908C P4 Spindle Bearing for CNC Machine Tool

The 71908C is a 15 degree C-series angular contact ball bearing built for continuous high speed running inside precision machine tool spindles. Its 40 mm bore, 62 mm outside diameter and 12 mm width allow it to sit inside compact spindle housings while still carrying meaningful axial and radial load. A single-row steel ball complement, a 15 degree contact angle and P4 dimensional accuracy let the bearing reach a limiting speed of 22000 RPM under grease lubrication and 36000 RPM with oil lubrication, keeping cutting tools rigid and thermally stable during high speed milling. Each unit is manufactured on a controlled automation line so bore, runout and contact angle remain consistent from batch to batch.

• High Speed Capability: The 15 degree contact angle and phenolic resin cage reduce internal friction and heat, supporting grease speeds up to 22000 RPM and oil speeds up to 36000 RPM for sustained high speed ceramic machining.
• P4 Precision Grade: P4 tolerances control bore, radial runout and face runout tightly, cutting vibration and improving surface finish on molds, dies and precision components.
• Steel Ball Rolling Body: Precision grade steel balls deliver high rigidity with a low friction coefficient, balancing stiffness and speed for general spindle duty.
• Outer Guide Cage: An outer guide phenolic formaldehyde cage guides the balls smoothly at high speed, lowering noise and extending bearing service life.
• Universal Fit 15 Degree: Matched to standard C-series dimensions, the bearing drops into common spindle designs and can be combined into DB, DT and DF arrangements.
• Stable Load Capacity: A basic dynamic load rating of 17.6 kN and static rating of 13.7 kN support both cutting forces and preload without distortion.

The 71908C suits machine tool spindle units for milling, drilling and boring, high speed motors, woodworking routers, precision grinding heads and measuring equipment. Because the bearing tolerates 22000 RPM grease speed and 36000 RPM oil speed, it works well where cycle times are short and spindle heat must be contained. It is also used in low noise test rigs and semiconductor process heads where a stable contact angle and predictable preload matter more than raw load capacity.

Each bearing is packed in a branded anti-rust paper wrap, held inside a shock absorbing foam insert and closed in an export grade corrugated carton. Units are protected against moisture and fine dust during sea and air transit. Every batch passes dimensional, vibration and running noise checks before shipment, and test reports covering precision, clearance and contact angle can be supplied on request. Mixed-model consolidation and custom kitting are available for OEM spindle builders.