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When a worn or undersized ball causes vibration, noise, or premature bearing failure, finding the exact replacement diameter matters. Machinists, maintenance technicians, and DIY builders who work with metric and fractional-metric assemblies need balls that meet tight dimensional tolerances — not catalog approximations. These G10 chrome steel precision bearing balls are stocked across a wide diameter range (5.9 mm to 30 mm / approx. 0.232" to 1.181") so you can match the original spec without custom ordering.
Each ball is manufactured from through-hardened chrome steel (GCr15 / 52100 equivalent) and finished to ABEC/ISO Grade 10 tolerances. Diameter increments as fine as 0.01 mm are available, covering both standard metric sizes and fractional-inch equivalents such as 7.938 mm (5/16"), 15.875 mm (5/8"), 19.05 mm (3/4"), and 25.4 mm (1"). Surface finish is smooth and consistent across the batch, supporting low-friction rolling contact.
Typical use cases include replacing rolling elements in deep-groove ball bearings, angular-contact bearings, and linear guides; restoring valve seats and check valves in hydraulic or pneumatic circuits; and serving as precision transfer balls in jigs, fixtures, and ball-transfer units. The 100-piece bulk packs are suited for production maintenance or repair shops that cycle through common sizes regularly.
| Material | Chrome steel (GCr15 / AISI 52100 equivalent) |
|---|---|
| Grade | G10 (ISO 3290 / ABEC Grade 10) |
| Hardness | Typically 60–66 HRC (through-hardened) |
| Diameter Range | 5.9 mm – 30 mm (approx. 0.232" – 1.181") |
| Diameter Tolerance | ±0.0025 mm (G10) |
| Surface Roughness (Ra) | Typically ≤0.025 µm |
| Roundness Deviation | See variant options |
| Surface Finish | Smooth, light anti-rust treatment |
| Pack Quantity | 1 pc or 100 pcs (select above) |
| Application | Radial ball bearings, angular-contact bearings, check valves, linear guides, jigs & fixtures |
Measure the existing ball with a micrometer or caliper, or check the bearing manufacturer's datasheet for the rolling element diameter. For standard deep-groove ball bearings, the ball diameter is listed in the bearing's internal geometry specification. If you are replacing a fractional-inch ball (e.g., 5/16"), look for the metric equivalent in our size list — 7.938 mm corresponds to exactly 5/16".
G10 (Grade 10 per ISO 3290) specifies the maximum allowable deviation in diameter, sphericity, and surface roughness. It is the standard grade used in most commercial and industrial ball bearings (ABEC 1–3 equivalent). For high-speed spindles or precision instruments requiring G5 or G3 balls, contact us to confirm availability before ordering.
Yes. Chrome steel (GCr15 / 52100) is compatible with all common mineral and synthetic bearing lubricants, including lithium-based greases, PAO oils, and ester-based lubricants. Avoid prolonged exposure to strong acids or chlorinated solvents, which can cause surface corrosion.
Chrome steel balls carry a light anti-rust treatment suitable for indoor mechanical environments. For outdoor, washdown, or submerged applications, stainless steel balls (AISI 440C or 316) are recommended instead. If you need stainless options, contact us for availability.
Load capacity depends on the complete bearing assembly — housing, races, and ball count — not the ball alone. The through-hardened chrome steel construction (60–66 HRC) provides the material strength required for standard radial and axial loads in commercial ball bearings. For specific dynamic or static load ratings, refer to your bearing manufacturer's catalog using the ball diameter and bearing series.
It is strongly recommended to replace all balls in a bearing at the same time, not just the damaged one. Mixing new and worn balls creates uneven load distribution, accelerating wear on the new balls and reducing bearing life. The ball count per bearing varies by series — check your bearing's datasheet or count the existing balls before ordering. The 100-piece bulk pack is ideal when servicing multiple bearings of the same size.
Yes. Sizes such as 7.938 mm (5/16"), 11.113 mm (7/16"), 15.875 mm (5/8"), 19.05 mm (3/4"), and 25.4 mm (1") are the exact metric equivalents of standard inch-series ball dimensions used in imperial bearings. These are manufactured to the same G10 tolerance and are direct replacements for inch-series rolling elements.
