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When metal bearings corrode, seize, or add unwanted weight to a precision build, engineers and hobbyists turn to POM plastic bearings with glass balls. These open (no-seal) miniature bearings are engineered for environments where moisture, chemicals, or electrical conductivity make steel a liability — from RC car wheel axles and drone frames to food-processing jigs and laboratory instruments.
Each bearing features a POM (polyoxymethylene) outer and inner ring paired with precision glass rolling elements. Available in 13 size options spanning 603 through 638 and specialty sealed variants, with inner diameters ranging from 3 mm (0.118 in) to 9 mm (0.354 in) and outer diameters from 9 mm (0.354 in) to 28 mm (1.102 in). Thickness runs 3–9 mm (0.118–0.354 in) depending on the selected size. Quantities are available from 1 to 50 pieces per order.
Typical use cases include RC vehicle wheel bearings where weight savings improve handling, aquatic or marine equipment where constant water exposure would rust steel bearings, food-grade conveyor or packaging machinery requiring non-metallic rolling elements, and medical or electronic assemblies where non-magnetic, non-conductive bearings are specified.
| Bearing Type | Deep Groove Ball Bearing (Miniature) |
|---|---|
| Ring Material | POM (Polyoxymethylene / Acetal) |
| Rolling Element | Glass Balls |
| Seal Type | Open / No Seal |
| Available Sizes | 603, 604, 605, 606, 607, 608, 609, 634, 635, 636, 638, 608-RS, 608-2RS |
| Inner Diameter (ID) | 3 mm – 9 mm (0.118 in – 0.354 in) — See variant options |
| Outer Diameter (OD) | 9 mm – 28 mm (0.354 in – 1.102 in) — See variant options |
| Width / Thickness (THK) | 3 mm – 9 mm (0.118 in – 0.354 in) — See variant options |
| Quantity per Order | 1 / 2 / 4 / 5 / 8 / 10 / 20 / 50 pcs — See variant options |
| Operating Temperature | Typically –40 °C to +100 °C (–40 °F to +212 °F) |
| Corrosion Resistance | Resistant to water, mild acids, and common solvents |
| Conductivity | Non-conductive, non-magnetic |
| Lubrication | Dry / unlubricated (open design) |
Match the bearing number (e.g., 608) to the bore (ID), outer diameter (OD), and width (THK) of your housing or shaft. The size notation in each variant name follows the format ID × OD × THK in millimeters — for example, 608 (8 × 22 × 7 mm). Measure your existing bearing or housing seat with calipers before ordering to confirm the fit.
POM bearings are well-suited for light-to-moderate radial loads at low-to-medium speeds. They are commonly used in RC vehicles, 3D printer carriages, fidget spinners, and small conveyor systems. They are not recommended for heavy industrial loads, high-speed continuous operation, or applications requiring the load capacity of steel bearings. If your load or speed requirements are demanding, contact us to confirm suitability.
No. Both the POM rings and the glass rolling elements are inherently corrosion-resistant. Unlike steel bearings, they will not rust when exposed to water, rain, or mild chemical splashes. The open (no-seal) design allows water to drain freely rather than pool inside the raceway, making them a practical choice for aquatic models, outdoor equipment, and food-processing machinery.
The open 608 has no seals on either side, offering the lowest drag and free drainage. The 608-RS has a single rubber seal on one side, providing light dust and splash protection while retaining some lubrication. The 608-2RS has rubber seals on both sides for better contamination exclusion and grease retention. For wet environments where drainage is needed, the open version is typically preferred; for dusty environments, -2RS offers better protection.
Yes. The dimensions follow standard metric miniature bearing designations (ISO 618 series for 60x sizes). They are drop-in replacements for steel bearings of the same size designation in most housings. Always verify the ID, OD, and width against your specific housing drawing, as some aftermarket or custom housings may have non-standard tolerances.
POM (acetal) is widely used in food-processing equipment due to its low moisture absorption, chemical resistance, and non-toxicity under normal conditions. Glass balls are also inert and non-metallic. However, formal food-grade or medical-grade certification requirements vary by jurisdiction and application. If your application requires documented compliance (e.g., FDA, EU food contact regulations), please contact us to confirm before ordering.
For a single repair or prototype, ordering 1–2 pieces is sufficient to verify fit and performance before committing to a larger quantity. For small-batch production runs or to keep spares on hand, the 10- or 20-piece options offer a better per-unit value. The 50-piece option is suited for ongoing production or resale needs.
