1. What Is a Self-Lubricating Oilless Bearing?

Self-lubricating oilless bearings combine a metal matrix that carries the load with solid lubricants — typically graphite or molybdenum disulfide (MoS₂) — embedded in machined holes or grooves on the friction surface. During operation, frictional heat and sliding action transfer a thin solid lubricant film onto the mating shaft surface. The bearing can therefore run with little or no external lubrication, which reduces maintenance intervals and removes dependence on a continuous oil film in dry, high-temperature, high-pressure, water-washed or chemically aggressive environments.

Solid lubricant coverage is a design parameter rather than a fixed value: small vehicle-type bearings may use roughly 25% coverage, while mechanism bearings under demanding duty may use up to 65% of the friction surface area. Coverage is specified by the bearing designer according to load, speed and lubrication conditions.

2. JDB Series Technical Specifications

Five JDB grades cover a spread of base materials from high-strength brass to steel-backed composites. Ratings below are reproduced from the source technical document and should be verified against material certificates before final specification.

Source: technical oilless bearing.docx (received 2026-08-28). “Allowable load at 1 m/min” refers to the unit originally printed as “1m/mm”, interpreted as sliding speed 1 m/min.

3. Base Materials & Cross-Standard References

Matrix material notes

• High-strength brass (JDB-1): nominal composition per the C86300 family — Cu 60–67, Al 5–7.5, Fe 2–4, Mn 2.5–5, Zn balance. Hardness is roughly double that of standard tin-bronze bushings, with correspondingly improved wear resistance under abrasive and high-load duty.
• Tin bronze 6-6-3 (JDB-2): higher density than high-strength brass, suitable for high-temperature, low-load service and good wear behaviour.
• Steel-backed composite (JDB-3): combines tin-bronze benefits with lower cost and higher compressive strength; the backing surface can be welded to support structures.
• Cast iron (JDB-4): economical option where pressure remains below about 14.5 N/mm².
• Bearing steel (JDB-5): compressive strength above the other grades in the series; unsuitable in water, acid or alkaline media.

4. Application Matrix

Grade preferences are indicative starting points based on the source document; confirm with load / speed / PV calculation and environment review.

5. Wear Performance Comparison

Comparative wear data from the source document, tested against an oil-lubricated CuSn6Zn6Pb3 bushing under three load levels. Test conditions and duration units as supplied; treat as comparative data, not design values.

Time unit as printed in the source (“10 / 30 / 100 / 20”); confirm hours vs. cycles with the test originator before citing.

6. Selection Guidelines

6.1 Load-based selection

• Light load: lining thickness 0.5 / 0.75 / 1.0 / 1.5 / 2.0 / 2.5 mm.
• For uneven loads, evaluate the load ratio (commonly written SB/D): light ~0.03–0.06, moderate ~0.08–0.12, heavy ~0.10–0.15.
• Bushing width is generally 0.5–3 mm beyond nominal; choose thickness for flexibility, load distribution and compensation for uneven surface wear.

6.2 Chamfer reference (2.5 mm thickness series, mm)

6.3 Clearance and thermal expansion

Because the mating shaft is typically steel, allow for thermal expansion in the shaft-to-sleeve clearance. Initial clearance in the 0.032–0.15 mm range may grow to roughly 0.45–0.5 mm as operating temperature rises. During the running-in period, provide adequate lubrication (where permitted) to reduce friction and energy consumption.

7. Installation & Maintenance Notes

7.1 Handling and installation

• Keep bearing and surrounding area clean; airborne dust increases wear, vibration and noise.
• Do not strike the bushing with a hammer or transmit force through the load zone; use a suitable press or dedicated tooling.
• Remove hand sweat before handling and apply a quality mineral oil; pay extra attention to anti-corrosion measures in rainy or humid seasons.
• For sliding bearings, ensure oil-film entry from non-load areas, unobstructed oil holes, no full-ring groove at the bearing centre, and no sharp edges that can cut the oil film.

7.2 Rust prevention for self-lubricating bearings

1. Clean the surface by solvent, chemical or mechanical methods appropriate to the part.
2. Dry with filtered compressed air, a dryer at 120–170 °C, or a clean cloth.
3. Protect with rust-preventive oil — by immersion (small parts), brushing (outdoor or shaped parts) or spraying at about 0.7 MPa with due fire-safety and labour-protection measures.

7.3 If bearing temperature rises during operation

1. Verify whether the alarm is genuine; if so, check cooling water pressure and flow, and clear filter blockages.
2. Check oil pressure at the speed regulator (low pressure can close cooling-water valves).
3. Listen for abnormal sound and check for abnormal play.
4. Sample the oil for colour change and degradation; replace if confirmed deteriorated.
5. Check the oil-level indicator; if draining, confirm the reservoir drain valve seals and repair if leaking.

8. Electroplating Notes for Porous Bronze Bearings

Cast bronze bearings have a porous structure; when electroplating is required, follow strict process control:

• Cleaning: clean thoroughly at every step to avoid solution residue in the pores.
• Silver plating: apply current while the bushing is submerged; use a shock current density for 5 minutes while shaking the workpiece, then switch to normal current density.
• Surface area difference: the true surface area is larger than the calculated area — use a shock current density about three times that of regular parts and extend pre-plating time.
• Copper pre-plating: shake workpiece and hanger frequently for a uniform coating and to prevent uneven spots.

9. Food-Contact & Environmental Note

10. Recommended Sources for Verification

• Material certificates (mill test certificates) for each production lot.
• GB/T 1176 and GB/T 9439 for Chinese cast copper alloys and grey cast iron; GB/T 18254 for GCr15.
• DIN 1705 / DIN 1709 and ASTM B584 / B271 / B505 for tin and aluminium brasses and bronzes.
• Bearing manufacturer PV and wear test reports for the specific grade and finish.