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Engineers, machinists, and DIY builders who work with precision assemblies know the frustration of sourcing rolling elements that meet tight dimensional tolerances without ordering in bulk from industrial distributors. These 100Cr6 bearing steel balls are stocked in an exceptionally wide diameter range — from 0.7938mm (1/32") up to 100mm (≈3.94") — so you can match the exact size your application demands, whether you're replacing a single ball or restocking a production line.
Each ball is manufactured from 100Cr6 (SAE 52100) through-hardened chromium bearing steel and finished to ABEC G10 grade. Diameters span 0.7938mm to 100mm (approximately 0.031" to 3.937"), with both metric and fractional inch sizes available. Surface finish is typically Ra ≤0.025 µm, and roundness deviation is controlled to G10 tolerances per ISO 3290.
Typical applications include deep-groove ball bearings, linear motion guides, check valves, and precision jigs where consistent ball diameter is critical. They are also widely used in bearing steel ball replacement for industrial machinery, miniature bearing assemblies in robotics, and load-distribution components in custom mechanical fixtures.
| Material | 100Cr6 / SAE 52100 Chromium Bearing Steel |
|---|---|
| Precision Grade | G10 (ISO 3290) |
| Diameter Range | 0.7938mm – 100mm (0.031" – 3.937") |
| Diameter Tolerance | ±0.25 µm (G10 grade) |
| Roundness Deviation | ≤0.25 µm |
| Surface Roughness (Ra) | ≤0.025 µm (typical) |
| Hardness | 60–66 HRC (typical, through-hardened) |
| Finish | Polished, bright |
| Available Quantities | 1, 5, 10, 20, 25, 50, 100, 200, 250, 500, 1000, 2000 Pcs |
| Size Standards | Metric and fractional inch |
| Typical Applications | Deep-groove bearings, angular contact bearings, thrust bearings, check valves, linear guides |
| Weight | See variant options |
Match the ball diameter to the race groove radius of your bearing. The ball diameter should be slightly smaller than the groove radius — typically the ball-to-groove ratio is 0.92–0.97. Refer to your bearing's datasheet or measure the existing balls with a micrometer. If you are replacing worn balls, measure the original diameter before ordering.
ISO 3290 grades define the maximum allowable deviation in roundness and diameter. G10 is a precision grade with roundness deviation ≤0.25 µm and diameter tolerance ±0.25 µm — tighter than G25 (≤0.63 µm) and significantly tighter than G100 (≤2.5 µm). G10 is suitable for precision instruments, high-speed spindles, and applications where vibration and noise must be minimized.
100Cr6 (SAE 52100) is a through-hardened chromium alloy steel, not stainless steel. It offers moderate corrosion resistance under dry or lightly lubricated conditions but will rust if exposed to moisture without lubrication or protective coating. For wet or corrosive environments, consider stainless steel (AISI 440C) or ceramic balls instead. Always apply appropriate bearing grease or oil when installing.
Yes, 100Cr6 steel balls are commonly used in check valves, hydraulic systems, and pneumatic applications where the fluid is non-corrosive (e.g., oil, compressed air). For water-based or acidic media, stainless steel or ceramic balls are recommended. Verify the ball diameter matches your valve seat bore for a proper seal.
Count the number of balls in your bearing before disassembly, or refer to the bearing manufacturer's specification sheet. Most standard deep-groove bearings use 7–12 balls depending on size. We offer packs from 1 piece up to 2,000 pieces — select the quantity that covers your repair plus a small reserve for future maintenance.
Not always. For example, 3.175mm is the exact metric equivalent of 1/8" (0.125"), and 6.35mm equals 1/4". However, some fractional sizes like 7.938mm (5/16") and 9.525mm (3/8") do not have a round metric counterpart. Always order by the exact diameter listed in the variant options rather than converting between systems to avoid dimensional mismatch.
Store in a dry, low-humidity environment away from direct contact with water or acidic substances. Keep in the original packaging or a sealed container. Apply a light coat of anti-rust oil if storing for extended periods (more than a few months). Avoid storing near magnets, as magnetized balls can attract debris and affect bearing performance.
