Application Matrix of Bronze Bushings in Overflow Ball Mill Rotary Systems
Application Matrix of Bronze Bushings in Overflow Ball Mill Rotary Systems
High-Performance Self-Lubricating Bronze Bushing Solutions & Technologies. Minimize downtime, extend service life, and reduce costs for dynamic applications.
Self-Lubricating Plain Bearings — Tolerance & Fit Quick Reference
General Engineering Edition | Dimensions in mm.
1. Composite Plain Bearing (steel backing + bronze + PTFE/POM)
| Nominal bore d | Nominal O.D. D | Bearing O.D. tol. | Housing | Shaft | Bore after mount |
| 6 | 10 | +0.055 / +0.025 | H7 | f7 | 5.990 ~ 6.055 |
| 8 | 12 | +0.055 / +0.025 | H7 | f7 | 7.990 ~ 8.055 |
| 10 | 14 | +0.065 / +0.030 | H7 | f7 | 9.990 ~ 10.058 |
| 12 | 16 | +0.065 / +0.030 | H7 | f7 | 11.990 ~ 12.058 |
| 16 | 18 | +0.065 / +0.030 | H7 | f7 | 15.990 ~ 16.058 |
| 18 | 20 | +0.075 / +0.035 | H7 | f7 | 17.990 ~ 18.061 |
| 20 | 23 | +0.075 / +0.035 | H7 | f7 | 19.990 ~ 20.071 |
Note: Wrapped-bushing O.D. tolerance wider than m6/n6; located by interference. Bearing-housing H7/p6; bore shrinkage after press-fit <=0.02 mm.
2. Bimetal Wrapped Bushing (CuSn8P, DIN ISO/3547)
| Diameter range | Bearing O.D. tol. | Housing | Bearing bore | Shaft |
| 10-18 | +0.065 / +0.030 | H7 | +0.018 / 0 (H7) | f7 |
| 18-30 | +0.075 / +0.035 | H7 | +0.021 / 0 (H7) | f7 |
| 30-50 | +0.085 / +0.045 | H7 | +0.025 / 0 (H7) | f7 |
| 50-80 | +0.100 / +0.055 | H7 | +0.030 / 0 (H7) | f7 |
| 80-120 | +0.120 / +0.070 | H7 | +0.035 / 0 (H7) | f7 |
Note: Service temp -40 to +150 C, alpha~18.5e-6/K, grease-lubricated allowable PV upper limit 2.8, allowable speed upper limit 2.5 m/s.
3. Solid-Embedded Bearing (high-strength brass + graphite)
| Nominal bore d | Nominal O.D. D | Bore tol. (F7) | O.D. tol. (m6) | Housing | Shaft |
| 12 | 18 | +0.034 / +0.016 | +0.018 / +0.007 | H7 | d7 / e7 |
| 16 | 22 | +0.034 / +0.016 | +0.021 / +0.008 | H7 | d7 / e7 |
| 20 | 28 | +0.041 / +0.020 | +0.021 / +0.008 | H7 | d7 / e7 |
| 25 | 33 | +0.041 / +0.020 | +0.025 / +0.009 | H7 | d7 / e7 |
| 30 | 38 | +0.050 / +0.025 | +0.025 / +0.009 | H7 | d7 / e7 |
Note: Upper service-temperature limit 300 C, allowable PV upper limit 3.8 N/mm²*m/s. Allow +0.01~0.03 mm solid-lubricant compensation.
4. Sintered Oil-Impregnated Bearing (GB/T 2685 system)
| Grade / wording | Description |
| Grade 7 / 8 / 9 | Graded by bore tolerance; example marking bearing 20G7x26x25; O.D. <=24 mm uses s9 |
| Design fit | Bore H7/E7, O.D. r6/s6 (interference); reserve 0.025-0.05 mm shrinkage allowance after press-fit |
| Standard ref | JIS B 1581:1976 (Oil impregnated sintered bearings) still effective |
5. Fit Design Principles
| Scenario | Fit recommendation | Note |
| General rotation, small clearance | Bearing bore H7/H8 x shaft f7 | Commonly used; free rotation with low impact |
| Low speed, high accuracy | Bearing bore H7 x shaft g6 / e7 | Sliding velocity <0.5 m/s to improve concentricity |
| Bearing-housing | Housing H7 x bearing O.D. interference | Composite may use H7/p6; wrapped bushing uses catalog O.D. tol. |
| Shaft journal | Hardness HRC 45+ (composite) | Roughness Ra 0.4-1.6 um; soft shaft may deform bore |
Note: Working clearance recommended 0.15%-0.3% of shaft diameter; enlarge for temperature rise or wash-down. H7/f7 at d=20 gives 0.020~0.062 mm clearance.
6. Additional Bearing Types
| Type | Structure / material | Typical tolerance & fit | Suitable for |
| Boundary-lubricated composite | Steel backing + bronze + modified POM, light oil film | Same as composite family; bore H7, shaft f7 | Boundary lube, high PV, reciprocating |
| Sintering bimetal bushing | Low-carbon steel + sintered bronze + solid lubricant (Pb/MoS2) | O.D. interference, bore H7~H8, shaft f7; dry to 250 C | Mining, automotive, heavy-load low-speed |
| Engineering polymer (PA/POM/PEEK) | Injection moulded, may embed solid lubricant | Bore H8~H9, shaft e7/f7; wider clearance for expansion | Food, underwater, corrosive, light-load |
| Oil-free linear bearing | Metal/polymer cage + guide elements | Per linear-motion standard, tighter clearance | Precision guidance, automation |
7. Service-Condition Notes
-
Elevated temperature >=300 C: Metal-based solid lubrication (bronze+graphite) or leaded bronze; enlarge clearance, check housing constraint.
-
Low temperature -195 C: PTFE-based composite (lower limit -195 C) usable; avoid embrittling materials.
-
Underwater / seawater: Stainless-steel-based or engineering polymer (PEEK/POM); corrosion-resistant, enlarge clearance.
-
Food-grade: Food-contact-compliant polymers (PTFE, food-grade engineering plastics, bronze+food-grade lubricant); lead-free variant; clearance +0.01~0.02 mm.
-
Dusty / abrasive: High-hardness bimetal (sintering type) or CuSn8P beats soft PTFE face; add dust seal.
-
Reciprocating / oscillating: Material with close static/dynamic friction (solid-embedded) to avoid stick-slip; smaller clearance, screw fix under load.
-
Heavy load, low speed: Solid-embedded or CuSn8P; check specific pressure & PV; add flange/thrust if needed.
-
High speed: Oil supply or PTFE-based; mid-range clearance; watch heat & PV upper limit.
Assembly Note: Do not strike with a hammer or apply direct heat that may damage the PTFE layer; press with an arbor, housing entry chamfer C0.5-C1; thin-wall may use freeze-fit.
8. ISO Tolerance-Band Lookup & Calculation
(GB/T 1800 / ISO 286)
Calculation Example:
For nominal diameter d=20:
-
Housing Bore H7 = +0.021 / 0
-
Shaft f7 = -0.020 / -0.041
-
Fit clearance = 0.020 ~ 0.062 mm.
Disclaimer: Engineering reference only. Follow latest effective standards, supplier catalogue and pilot press-fit data. The publisher accepts no liability for use in specific applications.Self-Lubricating Plain Bearings Tolerance
Metal Bushing (Lubricated Metal) -Self-Lubricating Bushing Materials
Bushings are specialized, self-lubricating metal components widely utilized across various industries due to their durability and low maintenance requirements. Self-lubricating metal bushings are engineered to function without additional lubrication in numerous applications, thereby minimizing maintenance needs. These bushings are available in various series and configurations, such as flanged bushings and split bearings, to meet specific application requirements.
Metal-Polymer Anti-Friction Plain Bearings
Metal-Polymer Composite Self-lubricating Bushing Material
Steel Back + Porous Bronze Sinter + PTFE
