Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
When a worn bearing surface causes vibration, noise, or premature failure in your machinery, finding the exact replacement diameter quickly is critical. Machinists, maintenance engineers, and DIY builders who need chrome steel loose ball bearings in a wide range of imperial sizes — from miniature 3.175 mm (1/8") up to 101.6 mm (4") — rely on consistent G25-grade roundness and surface finish to keep assemblies running true.
These loose ball bearings are manufactured from chromium chrome steel (commonly referred to as 52100-equivalent bearing steel), delivering a hardened, wear-resistant rolling element. Diameters span 3.175 mm to 101.6 mm (1/8" to 4"), with quantity options ranging from 1 piece to 5,000 pieces per order depending on the selected size. Each ball is ground to ABEC/ISO G25 grade, meaning roundness deviation is held to typically ≤0.63 µm and surface roughness to ≤0.032 µm Ra.
Typical applications include rebuilding or repacking radial ball bearings in electric motors and gearboxes, filling ball-screw or linear-rail recirculation tracks, restoring antique machinery with non-standard bore sizes, and prototyping custom bearing housings where off-the-shelf bearing assemblies are unavailable. The broad size range also makes these ideal for educators and students building mechanical engineering demonstration rigs.
| Material | Chromium chrome bearing steel (52100-equivalent) |
|---|---|
| Grade | G25 |
| Diameter Range | 3.175 mm – 101.6 mm (1/8" – 4") |
| Roundness Deviation | Typically ≤0.63 µm |
| Surface Roughness (Ra) | Typically ≤0.032 µm |
| Hardness | See variant options |
| Finish | Bright polished |
| Quantity Options | 1 / 2 / 5 / 10 / 20 / 30 / 40 / 50 / 100 / 200 / 500 / 1000 / 2000 / 5000 pcs (varies by diameter) |
| Unit Weight | See variant options |
| Application | Bearing housings, ball screws, linear guides, custom retainer cages |
Measure the inner diameter of your bearing housing or retainer pocket with a micrometer or digital caliper. The ball diameter should match the pocket diameter within the designed clearance — typically 0.005 mm to 0.02 mm for precision assemblies. Cross-reference with the original bearing manufacturer's specification sheet if available.
G25 is an ISO 3290 precision grade for ball bearings. It specifies that the diameter variation (difference between largest and smallest measured diameter on a single ball) and the lot diameter variation (spread across a batch) are both held to ≤0.63 µm. This level of precision reduces vibration, noise, and uneven load distribution in the bearing assembly.
Chromium chrome steel offers moderate corrosion resistance compared to carbon steel, but it is not stainless. For wet, humid, or chemically aggressive environments, consider applying a light bearing grease or oil after installation, or contact us to discuss stainless steel alternatives. Avoid prolonged exposure to water or corrosive fluids without lubrication.
Yes. Loose balls are commonly used in full-complement configurations where the housing or shaft groove retains the balls directly without a cage. Full-complement designs carry higher static loads but are limited to lower speeds due to ball-to-ball contact. Ensure the groove radius is 51–53% of the ball diameter for optimal load distribution.
Load capacity depends on the ball diameter, number of balls in the assembly, groove geometry, and operating speed. Larger diameter balls carry proportionally higher loads. For specific dynamic (C) and static (C₀) load ratings, refer to your bearing housing manufacturer's design data or consult a bearing engineer — these values are assembly-dependent, not a property of the loose ball alone.
Store balls in a clean, dry environment away from moisture, dust, and magnetic fields. Keep them in the original packaging or a sealed container with a light coating of anti-rust oil. Avoid storing near grinding equipment or other sources of metallic contamination that could embed particles in the polished surface.
Larger diameter balls (25.4 mm / 1" and above) are packaged individually or in small quantities due to their size and weight. Quantity options for these sizes are limited accordingly (typically 1–20 pieces). Select your size and quantity above to see the available options for your chosen diameter.
