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When a worn or undersized bearing causes vibration, heat build-up, or premature shaft failure, engineers and DIY machinists need a drop-in replacement they can trust. These genuine NSK ZZ and CM series deep-groove ball bearings are designed for builders, repair technicians, and hobbyists who refuse to compromise on dimensional accuracy or load capacity.
Each bearing is manufactured to NSK's deep-groove ball bearing standard, featuring a steel inner ring, steel outer ring, and a full complement of precision-ground steel balls retained between two metal shields (ZZ designation). The CM suffix denotes a standard internal clearance class. Available sizes span inner diameters from 10 mm (0.394 in) to 50 mm (1.969 in), outer diameters from 26 mm (1.024 in) to 110 mm (4.331 in), and widths from 8 mm (0.315 in) to 27 mm (1.063 in), covering the 6000, 6200, and 6300 series families.
Typical applications include electric motor shaft replacement bearings, skateboard and longboard wheel bearing upgrades, CNC spindle and router bearing swaps, bicycle bottom bracket and hub rebuilds, and small appliance or power tool bearing repairs — all scenarios where an ISO-standard deep-groove ball bearing with metal shields is the specified solution.
| Brand | NSK |
|---|---|
| Series | 6000, 6200, 6300 (ZZ, CM) |
| Bearing Type | Deep-Groove Ball Bearing |
| Shield Type | Double Metal Shield (ZZ) |
| Internal Clearance | CM (Standard / Normal) |
| Inner Diameter (I.D.) | See variant options (10 mm – 50 mm) |
| Outer Diameter (O.D.) | See variant options (26 mm – 110 mm) |
| Width (Thickness) | See variant options (8 mm – 27 mm) |
| Material — Rings & Balls | Bearing steel (chrome steel) |
| Material — Shields | Pressed steel |
| Lubrication | Factory-applied grease (sealed) |
| Quantity per Order | 1 PCS (per variant selected) |
| Dimensional Standard | ISO 15 / JIS B 1521 |
Match the bearing number to your application's specification. The variant label shows the bearing number (e.g., 6205 - ZZCM) alongside the dimensions in the format I.D × O.D × Width (mm). Measure your shaft diameter for the I.D. and your housing bore for the O.D. If you only have the old bearing number stamped on the ring, select the matching number from the Bearing No. dropdown.
All three are deep-groove ball bearings with the same bore diameter for a given number suffix, but they differ in outer diameter and width. The 6300 series has the largest cross-section (heaviest load capacity), the 6200 series is mid-range, and the 6000 series has the smallest cross-section. Always match the series to your housing dimensions, not just the bore.
ZZ indicates that the bearing has two metal (steel) shields, one on each side. The shields retain the factory grease and keep out coarse particles. Unlike rubber contact seals (2RS), metal shields do not touch the inner ring, so they produce slightly less friction — making ZZ bearings a good choice for higher-speed applications where a fully sealed bearing is not required.
CM is NSK's designation for standard (Normal/CN) internal radial clearance. It is the most common clearance class and is compatible with the vast majority of general-purpose applications including motors, fans, conveyors, and hand tools. If your application specifically requires C3 (greater clearance) or C2 (tighter clearance), you would need a different variant.
Standard ZZ bearings use chrome steel rings and balls, which offer good resistance to normal atmospheric conditions but are not rated for continuous water immersion or highly corrosive environments. The metal shields provide a barrier against light moisture and dust. For wet or marine environments, a stainless-steel bearing would be more appropriate.
Yes. Deep-groove ball bearings are manufactured to ISO dimensional standards, so an NSK 6205 ZZCM is dimensionally interchangeable with a SKF 6205-2Z, FAG 6205-2Z, or any other brand's equivalent bearing number. The outer dimensions (I.D., O.D., width) will be identical; only internal design details and tolerances may vary slightly between manufacturers.
No. ZZ-shielded bearings come pre-greased from the factory and are ready to install. Do not wash out the factory grease. If the bearing will operate at extreme temperatures or in a heavily contaminated environment, consult NSK's application guidelines for re-lubrication intervals.
Speed ratings vary by bearing number and size. Smaller bearings (e.g., 6000, 6200) typically support higher RPM than larger ones (e.g., 6308, 6310). Refer to the NSK bearing catalog for the specific grease speed limit (rpm) of your selected bearing number, or contact us to confirm for your application.
