603-6906 Silicon Nitride Full Ceramic Ball Bearings ID 3mm-35mm Si3N4 Insulation

Match the bore diameter (ID) to your shaft diameter and the outer diameter (OD) to your housing bore. The width must fit within your available axial space. Each variant in this listing shows the bearing number followed by ID × OD × Width in millimeters (e.g., 608 = 8 × 22 × 7 mm). Cross-reference these dimensions with your existing bearing number or measure your shaft and housing directly with calipers.

Yes. Silicon nitride ceramic has a volume resistivity exceeding 10¹⁴ Ω·cm, which is effectively an insulator at the voltages encountered in variable-frequency drive (VFD) applications. Replacing one or both bearings in a motor with Si3N4 full ceramic bearings breaks the conductive path that allows shaft currents to arc through the bearing raceways, a common cause of fluting damage in VFD-driven motors.

Silicon nitride has lower friction than steel and can operate dry in some low-load, low-speed scenarios. However, for most applications — especially higher speeds or loads — a compatible grease or oil is still recommended to reduce heat and extend service life. Avoid petroleum-based greases in chemically aggressive environments; use PTFE or ceramic-compatible lubricants instead. Contact us to confirm the best lubrication approach for your specific conditions.

Hybrid bearings use steel rings with silicon nitride balls, which improves speed and reduces wear compared to all-steel bearings but still conducts electricity through the rings and is susceptible to ring corrosion. Full ceramic bearings (Si3N4 rings and balls) provide complete electrical insulation, full corrosion resistance, and non-magnetic properties. Full ceramic bearings are the correct choice when electrical isolation or operation in corrosive or non-magnetic environments is required.

Silicon nitride is chemically inert, non-toxic, and does not shed metallic particles, making it suitable for food-processing wash-down environments and medical device applications where contamination control is critical. For regulated applications (FDA, EU food contact, ISO 13485 medical), verify that the specific lubricant used also meets the relevant compliance standard. Contact us if you need documentation support.

The maximum speed depends on the bearing size, load, lubrication, and mounting conditions. Because Si3N4 balls are approximately 60% lighter than steel balls of the same size, centrifugal forces on the raceways are significantly reduced, allowing higher DN values (bore in mm × RPM) than equivalent all-steel bearings. For specific speed ratings by size, contact us with your application details and we can provide guidance.

Yes — every size in this listing is available in a quantity of 1 piece, so you can order exactly what you need for a single-bearing repair or prototype. Multi-pack options (2, 5, 10, or 20 pcs) are also available at progressively lower per-unit pricing for production or maintenance stock.