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When a worn or undersized ball causes play, noise, or premature bearing failure, finding the exact diameter quickly matters. Machinists, maintenance technicians, and serious DIYers who work with miniature bearings, linear guides, ball screws, and valve seats need a reliable source for individually sized, dimensionally consistent steel balls — not a grab-bag assortment.
These bearing steel balls are manufactured from hardened chrome steel (GCr15 / 52100 equivalent), ground and lapped to a smooth, mirror-like surface. Diameters span φ1mm through φ20mm (approximately 0.039 in – 0.787 in), covering the most common metric and inch-fraction sizes used in standard and precision bearings. Roundness and surface finish are held to tight tolerances consistent with Grade G10–G25 rolling elements.
Typical use cases include replacing worn balls in deep-groove ball bearings and angular-contact bearings, loading ball-screw and linear-rail recirculation circuits, seating check valves and flow-control assemblies, and serving as gauge balls or reference spheres in metrology fixtures. Bulk packs of 500 pieces support production-line restocking, while small packs of 1–20 pieces suit one-off repairs and prototyping.
| Material | Chrome steel (GCr15 / AISI 52100 equivalent) |
|---|---|
| Surface Finish | Ground and lapped, bright polished |
| Hardness | Typically 60–66 HRC (see variant options) |
| Diameter Range | φ1mm – φ20mm (approx. 0.039 in – 0.787 in) |
| Grade (typical) | G10 – G25 (see variant options) |
| Available Quantities | 1 / 5 / 10 / 20 / 50 / 500 pcs (varies by diameter) |
| Application | Ball bearings, ball screws, check valves, linear guides, metrology |
| Corrosion Resistance | Moderate; apply light oil for storage in humid environments |
| Weight per piece | See variant options |
Check the bearing's datasheet or measure the existing balls with a micrometer. The ball diameter is not the same as the bearing bore (inner diameter) or outer diameter. Most bearing manufacturers publish full internal geometry specs, including ball diameter, in their product catalogs. If you are replacing worn balls, measure several from the same batch and use the average — worn balls may read slightly undersize.
Grade numbers refer to the maximum allowable deviation from a perfect sphere, measured in ten-millionths of an inch (0.1 µm increments). G10 balls deviate no more than 10 × 0.1 µm = 1 µm from a true sphere, while G25 allows up to 2.5 µm. For most repair and general-purpose bearing applications, G25 is sufficient. G10 is used in precision spindles, instrument bearings, and applications where noise and vibration must be minimized.
These balls are made from chrome steel (GCr15 / 52100), which offers moderate corrosion resistance in dry or lightly oiled indoor environments. They are not stainless steel. For applications exposed to water, chemicals, or high humidity — such as food-processing equipment, marine hardware, or medical devices — stainless steel balls (AISI 440C) are the appropriate choice. Contact us to confirm material compatibility for your specific environment.
No. All balls in a single bearing must be the same diameter to within the bearing's specified tolerance. Mixing diameters — even by a few micrometers — causes uneven load distribution, accelerated wear on the overloaded balls, increased vibration, and premature failure. Always replace the full complement of balls in a bearing at the same time, using balls from the same pack to ensure consistent sizing.
The 500-piece pack offers the lowest per-unit cost and is well suited for production-line restocking, batch assembly, or maintenance kits where a given diameter is consumed regularly. For one-off repairs or prototyping, the 1, 5, or 10-piece packs let you order only what you need. If your required quantity falls between available pack sizes, order the next size up — unused balls store indefinitely when kept dry and lightly oiled.
Store balls in a sealed container away from moisture and airborne contaminants. Apply a thin film of light machine oil or VCI (vapor corrosion inhibitor) oil before long-term storage. Avoid storing chrome steel balls in contact with dissimilar metals in humid conditions, as galvanic corrosion can occur. Properly stored, chrome steel balls retain their dimensional accuracy and surface finish indefinitely.
Yes. Several diameter options correspond to common inch-fraction sizes: φ3.175mm = 1/8 in, φ3.969mm ≈ 5/32 in, φ4.763mm ≈ 3/16 in, φ5.556mm ≈ 7/32 in, φ6.35mm = 1/4 in, φ7.144mm ≈ 9/32 in, φ7.938mm ≈ 5/16 in, φ9.525mm = 3/8 in, φ10.319mm ≈ 13/32 in, φ11.113mm ≈ 7/16 in, φ11.906mm ≈ 15/32 in, φ12.7mm = 1/2 in, φ14.288mm ≈ 9/16 in, φ15.081mm ≈ 19/32 in, φ15.875mm = 5/8 in, φ16.669mm ≈ 21/32 in, φ17.463mm ≈ 11/16 in, φ18.256mm ≈ 23/32 in, φ19.05mm = 3/4 in, φ19.844mm ≈ 25/32 in. Select the diameter that matches your bearing specification exactly.
