Flange Bushings: Self-Lubricating Bronze Flanged Bearings
Flange bushings are cylindrical plain bearings with an integrated radial bore and a single axial flange (collar) at one end. The flange acts as a locating shoulder and a thrust face, letting one component carry combined radial and axial loads without a separate thrust washer. This page covers construction, bronze grades, self-lubricating options, dimensional conventions, and selection for flanged bushings.
What Is a Flange Bushing
A flange bushing is a one-piece sleeve bearing with a protruding collar. The sleeve portion supports a rotating or oscillating shaft radially; the flange provides axial location and resists thrust in one direction. Because the locating shoulder is part of the same part, assembly is simpler than pairing a straight sleeve with a separate washer, and axial play is controlled at the bearing rather than the housing.
In plain-bearing terminology, a flanged bushing is the intermediate form between a sleeve bushing (radial only) and a thrust washer (axial only): it handles both, with radial capacity as the primary function and thrust as a secondary, usually lighter, load.
Construction and How It Works
The working surfaces are the inner bore (in contact with the shaft) and the flange face (in contact with the abutting component). Load is spread over the bore length for radial force and over the flange annulus for axial force. For self-lubricating versions, solid lubricant — typically graphite plugs or a graphite/PTFE-filled bronze matrix — is embedded in pockets across the bearing surface so the bushing runs without externally supplied oil or grease.
d, outer diameter D, flange diameter D1 (> D), bushing length L, flange thickness c. The flange is most often at one end, but double-flanged and flanged-with-lipped variants exist for specific location needs.Flanged vs Straight Sleeve vs Thrust Washer
| Feature | Flange bushing | Sleeve bushing | Thrust washer |
|---|---|---|---|
| Primary load | Radial (+axial) | Radial | Axial (thrust) |
| Integrated shoulder | Yes | No | N/A (flat) |
| Separate thrust part needed | No | Yes, if thrust present | No |
| Typical use | Shafts needing axial location | Free radial support | Pure axial faces |
Bronze Grades and Self-Lubrication
Flange bushings are produced from several copper-alloy families. Selection depends on load, environment, and whether the design must run without external lubrication.
| Alloy family | Examples | Notes for flange applications |
|---|---|---|
| Low-lead aluminum bronze | C95400, C95500, C63000 (nickel aluminum bronze) | High strength and corrosion resistance; suitable for self-lubricating graphite-filled builds in marine, outdoor, and heavy industrial duty. |
| Manganese bronze | C86300 | High mechanical strength for heavy combined loads; often used in construction and material-handling pivots. |
| Tin and leaded tin bronzes | C93200, C93700, C93800, C94300 | Good machinability and embeddability. These are leaded alloys (lead content varies by grade); they are not described as lead-free. |
Applications
Flange bushings appear wherever a shaft needs radial support plus axial location in one part:
- Construction and agricultural equipment — pivot joints, linkage ends, cylinder rod eyes. See the king pin bushings guide for industrial pivot examples.
- Material handling — conveyor pivots, lift-arm hinges, gate valves.
- Marine and outdoor structures — corrosion-exposed pivots using aluminum/nickel-aluminum bronze.
- Industrial machinery — gearbox covers, indexing fixtures, guide posts.
- Fitness and exercise equipment — see the gym equipment bearings guide for pivot and pulley locations.
Dimensions and Tolerances
Flanged bushings follow the same dimensional logic as wrapped and solid bushes: the bore is supplied undersized and finished by reaming or drilling to the shaft after installation, or supplied to a finished bore tolerance. Common starting references include ISO 3547 (wrapped bushes), ISO 4379 / DIN 1850 (solid bushes), and GB/T 2889 for plain-bearing vocabulary. A typical radial-fit pairing uses an H7 bore with an e7–e8 shaft; the flange face is held to a flatness and parallelism callout rather than a fit.
Dimension schematic
d (bore)DD1Lc (flange)
Size series by standard (indicative)
| Standard | Type | Series note |
|---|---|---|
| ISO 3547 | Wrapped bushing | Metric series; flanged variants listed in appendices. Confirm exact d / D / D1 / L with the standard or supplier. |
| ISO 4379 / DIN 1850 | Solid bronze bush | Metric sizes; flanged options available. |
| GB/T 2889 | Vocabulary | Defines d, D, L, c and related terms. |
| GB/T 23894 / 12613 | Sintered / flanged | Metric; used for sintered flanged bearings. |
Exact dimensional series are defined by the cited standards and supplier stock; this page does not publish specific d / D / D1 / L values without reference to a stated standard.
How to Specify a Flange Bushing
Use the table below as a specification checklist when requesting a quote. Provide as many parameters as the application defines.
| Parameter | What to provide | Notes |
|---|---|---|
Bore diameter d |
Shaft size | Finished bore, or reamed after installation. |
Outer diameter D |
Housing bore | Usually an interference / press fit. |
Flange diameter D1 |
Housing locating face | Must be > D to act as a shoulder. |
Length L |
Axial spread of radial load | Longer L spreads radial load. |
Flange thickness c |
Axial thrust capacity | Thicker c resists more axial load. |
| Alloy / grade | e.g. C95400, C86300, C63000, C93200 | Leaded grades are not described as lead-free. |
| Lubrication | External or self-lubricating (graphite) | Choose self-lubricating where maintenance access is limited. |
| Fit / tolerance | e.g. H7 bore / e7–e8 shaft | Per ISO / DIN as applicable. |
| Referenced standard | ISO 3547 / 4379 / DIN 1850 / GB-T | If a standard series applies. |
Mounting and Installation
- Housing bore: a press (interference) fit retains the bushing; the flange seats against a machined shoulder so axial location is set at the bearing.
- Reamed-after-install: where the tightest fit is needed, supply the bore undersized and ream to the shaft after fitting.
- Flange face: hold flatness and parallelism so the thrust load spreads evenly across the annulus.
- Do not overuse the flange for thrust: for loads beyond the flange annulus capacity, pair with a dedicated thrust washer or select a heavier section.
Axial Load and Flange Face Capacity
Axial (thrust) load on a flange bushing is carried over the flange annulus — the ring area between the flange outer diameter and the hub/bore region it bears against. Capacity depends on that area, the bronze grade, the lubrication type, and the contact condition; it is not a single fixed number. For higher axial loads, use a dedicated thrust washer or a flange-plus-washer combination. No performance, temperature, or service-life figures are stated here without a documented specification.
Flange Bushing vs Related Terms
The same words are used for different product classes. Clarifying them helps avoid mismatched procurement:
| Term | What it usually means |
|---|---|
| Flange bushing / flanged bronze bushing | A one-piece plain bearing with a radial bore and integral flange (this page). |
| Flanged bearing | Often a housed or rolling-element unit; a different product class from a plain bushing. |
| Pillow block (flanged) | A mounted bearing assembly with a base/housing; the flange here is the mounting face, not a plain-bearing collar. |
Custom vs Standard Flange Bushings
Standard: common sizes from ISO 3547 / ISO 4379 / DIN 1850 series — faster turnaround and lower cost for typical applications. Custom CNC: non-standard d / D / D1 / L, special alloys, groove patterns, or features such as keyways and peripheral graphite plug layouts. For application examples see king pin bushings (industrial pivots) and gym equipment bearings.
Applications Across Diverse Industries
Flange bushings are one part of a broader range of bronze plain-bearing solutions. For application-specific guidance, see our king pin bushings guide for construction and agricultural pivots, the gym equipment bearings guide for fitness machines, and the graphite bronze bushings guide for self-lubricating service. The bronze bushing pillar covers types, grades, and selection across the full product range.
Selection Checklist
- Confirm load type: mostly radial with light axial → flange bushing; pure axial → consider a thrust washer; radial only → a sleeve bushing.
- Choose alloy by environment (corrosion, load) and by whether leaded grades are acceptable for the application.
- Decide lubrication: externally lubricated bronze, or self-lubricating graphite-filled (oilless bushings / graphite bronze) where maintenance access is limited.
- Define bore/shaft fit (e.g., H7/e7–e8), flange diameter and thickness from housing geometry.
- Verify the flange face carries the thrust load within the annulus area, not the bore.
