Machine-tool spindles
Higher DN limits and lower running temperature mean less thermal growth — and better dimensional accuracy at the tool tip.
A hybrid bearing pairs steel rings with Si₃N₄ balls — about 60% lighter, harder than bearing steel and electrically insulating. That combination is what lets spindles, turbines and EV motors run faster, cooler and longer than an all-steel design allows.
At speed, a steel ball's own weight becomes its enemy: centrifugal force loads the outer race, raises friction heat and eventually skids the ball. A ceramic ball removes most of that mass while adding hardness, insulation and corrosion resistance — so the same bearing geometry reaches a higher DN and a longer life.
Three ball materials, three trade-offs. The right answer depends on speed, temperature, load type and media — not on the datasheet alone.
| Property | Bearing steel (GCr15) | Zirconia (ZrO₂) | Si₃N₄ |
|---|---|---|---|
| Density (g/cm³) | ~7.8 | ~6.0 | ~3.2 |
| Hardness (HV) | ~700 | ~1200–1300 | 1500–1800 |
| Electrical behaviour | Conductive | Insulating | Insulating |
| Corrosion resistance | Poor — rusts | Good | Excellent |
| Relative ball weight | Baseline | ~77% of steel | ~41% of steel |
| Best for | Heavy, shock-loaded, low-speed duty | Cost-sensitive insulation, lower speed | High speed, high temperature, electrical and corrosive duty |
When steel is still the better answer: for very heavy, shock-loaded or low-speed applications, the higher cost and lower fracture toughness of ceramic (versus ductile steel) may not pay off. We say so when it is true — and help you decide with a duty-cycle review rather than a catalogue page.
| Item | Standard capability |
|---|---|
| Grade | G5 / G10 / G20, per the ISO 3290 ball-grade convention. |
| Diameter | 3 – 50 mm; custom sizes quoted on request. |
| Sphericity | ≤ 0.13 µm at G5; ≤ 0.25 µm at G10. |
| Surface finish | Ra ≤ 0.02 µm (polished). |
| Material | Gas-pressure sintered Si₃N₄, HIP densified, ≥ 3.20 g/cm³ — above 99% of theoretical density. |
| Hardness | 1500 – 1800 HV10. |
| Supply form | Loose balls; hybrid sets (Si₃N₄ balls with steel rings); full-ceramic assemblies. |
| Inspection | 100% visual and dimensional inspection; grade report with sphericity and roughness values on request. |
Balls are supplied clean and individually protected to keep the polished surface intact in transit — a scratched ball is a rejected ball.
Higher DN limits and lower running temperature mean less thermal growth — and better dimensional accuracy at the tool tip.
Insulating balls stop shaft currents from arcing through the races, the classic cause of inverter-bearing failure.
Low mass and oil-free tolerance suit turbochargers, gyros, vacuum pumps and other high-speed or lube-starved duty.
Also supplied for pumps handling aggressive media, wind-turbine generators, and food, chemical and medical equipment where rust or contamination rules steel out.
NDA signed on request before drawings or test data change hands.
NitriCeram is a brand of Shandong Dolphin Technology Co., Ltd., with an integrated line from silicon nitride powder synthesis through forming, gas-pressure sintering, HIP, precision grinding and lapping, and in-house testing. Ball grinding and lapping are done in-house, so sphericity and surface finish are controlled at the process rather than negotiated with a subcontractor.
Tell us the speed, load, temperature and media — we reply within 24–48 hours with the right grade, diameter and tolerance class, or an honest note that steel still wins for your case.
Reading first? See the technical article Why Hybrid Bearings Use Silicon Nitride Balls.
