NLHB manufactures miniature ball bearings in our own factory in Cixi, Ningbo — MR metric, thin-section, flanged and inch sizes, in chrome or stainless steel, with steel or ceramic balls and precision up to P4. This guide explains how to choose the series, closure and material, and what to send us for a quotation.
Made in our own factory
Turning, raceway grinding, super-finishing and assembly of our miniature bearings are done in-house in Cixi, with every batch inspected for dimensions, clearance and vibration before packing.
Miniature series we produce
| Series | Examples | Typical use |
|---|---|---|
| MR metric miniature | MR63, MR85, MR105, MR128 | Small motors, instruments, robot vacuum brushes, models |
| Small 6xx series | 683, 693, 694, 695 | Drone and brushless motors, fans, small gear units |
| Thin-section 67 / 68 / 69 | 6800, 6801, 6900 | Compact assemblies, robot vacuum brush rolls, rollers |
| Flanged MF / F | MF85, MF105, F693 | Housings without a shoulder, pulleys, 3D printers |
| Inch R series | R2, R3, R4, R144 (SR144) | US-designed equipment, dental handpieces |
Materials, cages and precision
| Option | Choices | When to use |
|---|---|---|
| Rings | Chrome bearing steel · stainless steel | Stainless for moisture, cleaning agents or sterilization |
| Balls | Steel · silicon nitride (Si₃N₄) ceramic | Ceramic for high speed, lower heat and longer life under poor lubrication |
| Cage | Steel · nylon | Chosen per customer requirement for speed, noise and temperature |
| Closure | Open · ZZ metal shields · 2RS rubber seals | ZZ for low friction; 2RS where dust and moisture are the main risk |
| Precision | Up to P4 | P4 for dental and other high-speed precision applications |
Applications
Robot vacuums & home appliances
Side brushes, main brush rolls and drive wheels use shielded miniature and thin-section bearings such as MR128ZZ, 683ZZ, 693ZZ and 6800ZZ. Low noise and dust protection matter most.
Drones & small motors
Brushless drone motors commonly use 3 × 8 mm class bearings such as 693ZZ. Consistent clearance and low vibration keep motors smooth and quiet at high speed.
Dental handpieces
High-speed turbines use inch SR144-type bearings with stainless rings and ceramic balls, built to high precision and exposed to repeated steam sterilization.
MR85 and MR85ZZ specifications
| Model | d × D × B (mm) | Closure | Balls | Cr | C0r |
|---|---|---|---|---|---|
| MR85 | 5 × 8 × 2.0 | Open | 8 × Ø1.0 mm | 310 N | 120 N |
| MR85ZZ | 5 × 8 × 2.5 | Two metal shields | 8 × Ø1.0 mm | 310 N | 120 N |
Load ratings calculated from our ball complement by the ISO 281 / ISO 76 basic formulas. Other manufacturers' MR85ZZ designs may use a different ball set and therefore list different ratings.
Dental handpiece bearings
We produce SR144-type bearings (3.175 × 6.35 × 2.38 mm) with stainless steel rings and silicon nitride ceramic balls in P4 precision, and have tested them under 134 °C steam sterilization. Cage material is chosen with the customer. Test conditions and records are available with the quotation.
Inspection
What to send for a quotation
- Full designation with suffix, or a drawing / sample photo.
- Quantity and target delivery.
- Application and mounting position (for example: robot vacuum side brush, drone motor, dental turbine).
- Closure, cage and material requirements (ZZ / 2RS, steel / nylon cage, stainless, ceramic balls).
- Precision, clearance and noise grade if specified.
- Speed, temperature and any sterilization or cleaning requirement.
Frequently Asked Questions
What is the difference between MR85 and MR85ZZ?
Both are 5 × 8 mm miniature bearings. The open MR85 is 2.0 mm wide; MR85ZZ has two metal shields and is 2.5 mm wide. In our production both use eight 1.0 mm balls.
Should I choose ZZ or 2RS for a miniature bearing?
ZZ metal shields give low friction and suit higher speeds in relatively clean conditions. 2RS rubber seals keep out more dust and moisture but add friction. Tell us the speed and environment and we will recommend one.
Can you make stainless steel and hybrid ceramic miniature bearings?
Yes. We produce miniature bearings with stainless steel rings and with silicon nitride ceramic balls, and cages in steel or nylon according to your requirement.
Do you make dental handpiece bearings?
Yes. We produce SR144-type dental bearings (3.175 × 6.35 × 2.38 mm) with stainless steel rings and ceramic balls in P4 precision, and we have run 134 °C steam sterilization tests. Test conditions are provided with the quotation.
What do you need for a miniature bearing quotation?
The full designation or a drawing, quantity, the application and mounting position, closure, cage and material requirements, precision and clearance grade, and any noise or sterilization requirement.
Related guides
Published 2026-09-24. Images are representative. Final dimensions, ratings, inspection limits and supply conditions are confirmed against the requested model, drawing and order.