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When a standard bearing is too large and a generic substitute won't hold tolerance, engineers and makers reach for stainless steel mini deep groove ball bearings. These 603ZZ–698ZZ series bearings are designed for robotics builders, RC hobbyists, medical-device prototypers, and precision-instrument technicians who need reliable radial load capacity in a compact envelope.
Each bearing is manufactured from either Stainless Steel 440 (martensitic, higher hardness, HRC 58–62) or Stainless Steel 304 (austenitic, superior corrosion resistance in wet or chemical environments). Bore diameters span 3–9 mm (0.118–0.354 in), outer diameters 9–26 mm (0.354–1.024 in), and widths 4–8 mm (0.157–0.315 in). Both grades feature double metal shields (ZZ) to retain grease and exclude light contamination.
Typical applications include 3D printer carriage assemblies requiring low-friction linear motion, drone motor mounts demanding vibration-damped radial support, and laboratory stirrer shafts where stainless steel mini deep groove ball bearings resist reagent splash. Quantities from 1 to 10 pieces let you stock exactly what a repair or prototype run requires.
| Bearing Type | Deep Groove Ball Bearing |
|---|---|
| Shield Configuration | ZZ (Double Metal Shield) |
| Material Options | Stainless Steel 440 / Stainless Steel 304 |
| Bore Diameter (ID) | 3–9 mm (0.118–0.354 in) |
| Outer Diameter (OD) | 9–26 mm (0.354–1.024 in) — see variant options |
| Width | 4–8 mm (0.157–0.315 in) — see variant options |
| Size Series | 603ZZ, 604ZZ, 605ZZ, 606ZZ, 607ZZ, 608ZZ, 609ZZ, 623ZZ, 624ZZ, 625ZZ, 626ZZ, 627ZZ, 628ZZ, 629ZZ, 684ZZ, 685ZZ, 686ZZ, 687ZZ, 688ZZ, 689ZZ, 694ZZ, 695ZZ, 696ZZ, 697ZZ, 698ZZ, 699ZZ |
| Lubrication | Factory-greased |
| Operating Temperature | Typically −10°C to +120°C (14°F to 248°F) |
| Load Direction | Radial + moderate axial (both directions) |
| Available Quantities | 1 pcs / 2 pcs / 5 pcs / 10 pcs |
| Certification / Standard | See variant options |
SS440 (martensitic stainless steel) is heat-treated to a hardness of approximately HRC 58–62, giving it higher load capacity and wear resistance — a good choice for dry or lightly lubricated, higher-load applications. SS304 (austenitic stainless steel) cannot be hardened by heat treatment but offers significantly better corrosion resistance in wet, saline, or mildly acidic environments. Choose SS440 for mechanical performance; choose SS304 for chemical or moisture exposure.
You need three dimensions: bore (ID), outer diameter (OD), and width. Measure the shaft diameter to determine the bore, then check the housing bore for the OD, and confirm the axial space available for the width. All three dimensions are listed in the variant name — for example, 608ZZ【8×22×7mm】 means ID 8 mm, OD 22 mm, width 7 mm. If you are replacing an existing bearing, the size code is usually stamped on the shield.
These are ZZ double-metal-shielded bearings, not rubber-sealed (RS or 2RS). Metal shields retain grease and block coarse particles but do not form a contact seal, so they allow slightly more contamination ingress than rubber seals. The advantage is lower drag torque and suitability for higher-speed applications. For dusty or wet environments where contamination is a concern, consider adding an external seal or choosing a rubber-sealed variant.
Deep groove ball bearings can accommodate moderate axial loads in both directions in addition to their primary radial load capacity. They are not designed for predominantly axial applications — for those, angular contact or thrust bearings are more appropriate. For light-to-moderate combined radial and axial loads typical in motors, pulleys, and small machinery, these bearings perform well.
Each bearing is factory-greased before the metal shields are fitted. Because the ZZ shields are not permanently crimped on all designs, some users carefully remove a shield, add grease, and refit it — however, this risks damaging the shield or introducing contamination. For most applications, the factory grease is sufficient for the bearing's service life. If re-lubrication is a regular maintenance requirement, consider open or rubber-sealed variants that are easier to service.
These bearings are typically rated for continuous operation from approximately −10°C to +120°C (14°F to 248°F) with standard grease. SS304 retains its corrosion resistance across this range. SS440 maintains its hardness up to around 150°C before tempering effects begin. If your application exceeds 120°C, contact us to confirm suitability or discuss high-temperature grease options.
There is no minimum order — you can purchase as few as 1 piece per variant. Pack sizes of 1, 2, 5, and 10 pieces are available for each size and material combination, allowing you to order exactly what a repair, prototype, or small production run requires without committing to bulk quantities.
