Oil Free Bushing Flanged Type: Sizes, Fits and Load Limits
Oil Free Bushing Flanged Type
A flanged oil-free bushing is a plain bronze sleeve with the locating shoulder machined into the part itself. The sleeve carries radial load; the flange takes axial load and fixes where the bushing sits in the housing. For equipment builders and repair shops, the appeal is largely practical: one flanged bushing replaces a sleeve plus a separate thrust washer or retaining plate, which means fewer parts, one press operation instead of two, and no risk of the washer being left out during reassembly. This page describes what the flange does, which flange forms exist, typical proportions and size ranges, press-fit practice, the cases where a plain sleeve is the more sensible choice, and the graphite-plugged version for dry running.
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Flanged Oil Free Bushing Manufacturer
Flanged oil-free bushing is specialized components crafted for applications where shaft support perpendicular to the bearing’s mounting surface is necessary, all without the need for lubrication. These bushings excel in scenarios with high loads and low speeds, prized for their capacity to operate in harsh conditions without upkeep.
What the flange does
Four jobs are worth separating, because they drive different dimensional decisions:
- Axial location. The flange face registers against the housing face, so the bushing returns to the same axial position every time the joint is rebuilt. This is the reason flanged forms are standard on split pillow-block style housings and on linkages where shaft end position sets the stroke of the mechanism.
- Axial (thrust) load. The flange takes the force that would otherwise push the bushing out of the bore or load a shaft shoulder against a hub face. Capacity is set by the annular area of the flange face and the allowable surface pressure of the alloy.
- Retention against creep. In vibrating assemblies, a pressed sleeve can slowly walk out of its housing. A flange mechanically blocks that movement, and a flange with bolt holes blocks rotation as well; see the bolted thrust-type oilless bearings form and flanges machined with countersunk bolt holes.
- Shielding the joint line. The flange covers the gap between bushing OD and housing bore so abrasive dust or process water does not reach it, which slows down fretting corrosion at the press interface.
The limit to keep in mind: a flange is a thrust face of limited area, not a thrust bearing. Once the required thrust capacity exceeds what the flange face can carry at the allowable pressure of the alloy, the standard answer is a sleeve plus separate components such as bronze thrust washers on one or both sides, rather than growing the flange until it dominates the part.
Flange bushing forms available
The shoulder can sit at one end, at both ends, or somewhere along the length. Which one suits a given assembly depends mostly on the direction of the axial force and on how the part has to be installed.
| Form | Where the shoulder sits | Typical use | Notes |
|---|---|---|---|
| Single flange | One end of the sleeve | Most common form; shaft enters from one side, thrust acts in one direction | Simplest housing — only one machined face and, if needed, one counterbore |
| Double flange | Both ends of the sleeve | Housings where the assembly can be inserted from either side, or where thrust reverses | Requires axial access over the full length; machining cost is higher |
| Centre flange | Mid-length of the sleeve | Axial force arrives from both directions; the part is retained in a groove or split housing | Installation access matters more; the two lands either side must be bored concentric |
| Bolted or square flange | One end, extended to a pad with bolt holes | Heavy axial pulsing, rotation of the bushing must be prevented | Bolt torque and hole spacing should be on the drawing |
| Trimmed or half-width flange | One end, with part of the flange machined away | Axial space is restricted on one side, or clearance against a neighbouring part | Flat is machined to a chord; reduces thrust area proportionally |
Standard round-flange production and typical dimensions for the plain single-flange type are summarised on the round flange bronze bushing page.
Typical dimensions and proportions
The numbers below describe what is normally machined, not what is possible in principle. Flange dimensions are usually derived from the wall thickness rather than being independent quantities: the flange OD grows roughly proportionally to the sleeve OD, and the flange thickness tracks the wall thickness. When a drawing arrives with a flange thickness larger than twice the wall, we confirm whether the intent is really a thrust member, because that is usually the cheaper way to solve it.
| Sleeve OD band | Typical ID | Wall thickness | Flange OD | Flange thickness | Typical OD interference | Length range |
|---|---|---|---|---|---|---|
| 8–30 mm (0.31–1.18 in) | 6–25 mm | 1.0–3.0 mm (0.04–0.12 in) | 1.30–1.55 × OD | 2–4 mm (0.08–0.16 in) | 0.02–0.05 mm (0.0008–0.0020 in) | 8–40 mm (0.31–1.57 in) |
| 30–60 mm (1.18–2.36 in) | 25–50 mm | 2.5–5.0 mm (0.10–0.20 in) | 1.25–1.45 × OD | 3–7 mm (0.12–0.28 in) | 0.04–0.08 mm (0.0016–0.0031 in) | 10–80 mm (0.39–3.15 in) |
| 60–120 mm (2.36–4.72 in) | 50–105 mm | 4.0–8.0 mm (0.16–0.31 in) | 1.20–1.35 × OD | 5–12 mm (0.20–0.47 in) | 0.06–0.12 mm (0.0024–0.0047 in) | 20–150 mm (0.79–5.91 in) |
| 120–250 mm (4.72–9.84 in) | 105–220 mm | 6.0–14.0 mm (0.24–0.55 in) | 1.15–1.30 × OD | 10–20 mm (0.39–0.79 in) | 0.10–0.18 mm (0.004–0.007 in) | 40–250 mm (1.57–9.84 in) |
| Above 250 mm (9.84 in+) | 220 mm and above | 10–25 mm and heavier | 1.12–1.25 × OD | 15–30 mm (0.59–1.18 in) | 0.15–0.30 mm (0.006–0.012 in) | Per drawing |
Wall-to-bore ratio also matters for heat dissipation and for how much the bore closes during pressing. A rule of thumb used in this size range is that very thin walls follow the housing rather than holding their own roundness, so thin-wall parts rely more on housing accuracy.
Two checks before finalising flange thickness:
- Face pressure. Divide the peak axial force by the annular area of the flange face, π/4 × (flange OD² − sleeve OD²). Compare it with the allowable surface pressure for the selected alloy at the operating speed; typical dry-running figures sit in the range of roughly 30–100 MPa depending on base alloy and plug layout.
- Fillet clearance. Every integrally machined flange has a fillet at the junction with the sleeve. If the housing has not been relieved with a chamfer or counterbore, the bushing seats on the fillet instead of on the flange face, and the flange is then bent rather than supported. Allow relief of the fillet radius plus about 0.5–1.0 mm (0.02–0.04 in).
Typical dimensions and proportions
Materials used for flanged oil-free bushings
Any bearing bronze can be turned into a flanged part, so the flange form is rarely the deciding factor in alloy selection — load, speed, temperature and environment are. The figures below are typical room-temperature values; the ones on the material certificate for each heat govern.
| Alloy family | Typical hardness | Tensile strength, typical | Where it is used | What to check first |
|---|---|---|---|---|
| C93200 leaded tin bronze (SAE 660) | 60–80 HB | 240–310 MPa | General machinery, moderate loads, dirty environments, softer shafts | Low hardness limits PV; lead content may conflict with RoHS or potable-water rules |
| C90500 tin bronze (SAE 62, CuSn10Zn2) | 80–100 HB | 300–380 MPa | Heavier loads and shock, press and gearbox bushes | Lower embeddability; wants a harder shaft than C93200 |
| C86300 manganese bronze | 180–240 HB | 750–830 MPa | Very high loads at low speed, slow oscillation | Needs reliable lubrication; usually ordered graphite-plugged for dry service |
| C95400 and other aluminum bronzes | 170–220 HB | 585–690 MPa | High load, corrosive or seawater service, elevated temperature | Requires hardened shaft, typically above 250 HB, with a fine finish |
| CuSn8 wrapped strip (thin wall) | Depends on temper | Per strip specification | Space-limited housings needing 1.0–2.5 mm (0.04–0.10 in) wall | Formed from strip, not machined to size; not a repair-friendly option |
| Graphite-plugged versions of the above | Follows the base alloy | Follows the base alloy | Where no external oil or grease is possible | Plug coverage and layout set the PV capability — see below |
A wider comparison of alloy properties, including standards coverage, is kept on the common bearing materials page. For high-load aluminum bronze options there is a dedicated note on C954 aluminum bronze bushings, and for very high static loads on C86300 manganese bronze bushings.
Matching the bushing to the operating condition
| Condition | Commonly specified | Reason |
|---|---|---|
| Dry running, no external lubrication | Graphite-plugged bronze on a C86300 or C95400 base | Solid lubricant plugs transfer a film to the shaft without oil |
| Moderate load, occasional greasing | C93200 leaded tin bronze, solid | Embeds dirt and tolerates imperfect shafts |
| High radial load with slow oscillation | C95400 aluminum bronze or C86300 manganese bronze | Higher hardness resists brinelling at the oscillation ends |
| Axial thrust in one direction, moderate | Single flange, integral | Fewest parts; flange face carries axial load |
| Axial thrust reversing direction | Double flange, centre flange, or washers both sides | One face alone cannot react force from both sides |
| Seawater, splash zone, wash-down | Aluminum bronze or gunmetal with graphite plugs | Corrosion resistance plus the ability to run with a washed-out film |
| Elevated temperature, roughly 150–250 °C (300–480 °F) | Graphite-plugged aluminum bronze | Graphite remains effective where oil would oxidise |
| Limited radial space | Wrapped thin-wall form | 1.0–2.5 mm (0.04–0.10 in) wall saves radial room |
For oilless operation, limiting PV figures quoted for graphite-plugged bronze typically fall around 1.0–2.5 MPa·m/s, while an unplugged bronze running with no lubricant film at all must stay far below that. Coefficient of friction in dry sliding commonly lands between about 0.10 and 0.20 once the transfer film is established. All three numbers should be confirmed against the datasheet for the specific plugged material.
Press fit, clearance and bore closure
- Housing bore. H7 is the usual starting point, with the matching bushing OD tolerance selected to give the interference shown in the dimension table. A steel or cast-iron housing takes a heavier interference than aluminum; aluminum usually calls for a lighter fit or a retaining feature.
- Bore closure. Pressing a bushing into a rigid housing shrinks the bore. Depending on wall thickness ratio, the bore closes by roughly 0.6 to 1.0 of the OD interference. For tight clearances this is handled either by boring the pre-press size oversize, or by finishing the bore after installation by reaming or honing.
- Running clearance. Commonly 0.1–0.2% of shaft diameter, plus allowance for thermal growth of the shaft during operation. A 50 mm (1.97 in) shaft therefore usually starts around 0.05–0.10 mm (0.002–0.004 in) diametral clearance.
- Shaft condition. For oilless running, a shaft hardness above roughly 250–300 HB with a finish of Ra 0.4–0.8 µm (16–32 µin) is normally requested; a soft shaft will be scored rather than polished.
- Measurement. Bore dimensions should be read at the same temperature, normally 20 °C (68 °F), with the same equipment used at final inspection; details are in reading and measuring bearing tolerance.
- Installation force. Press on the bushing OD with a mandrel that contacts the flange face squarely, never on the flange OD or across the bore, and seat the flange fully against the housing face before measuring.
Graphite-plugged flanged bushings
When no external lubricant can reach the bearing, rows of solid lubricant plugs are embedded in the bore. Plugs release a transfer film in the first few tens of cycles; after that the bushing runs with no oil supply and no re-greasing interval. Typical plug coverage is around 20–30% of the bearing surface for rotary service, and higher for slow oscillation or linear sliding, with grid pitch usually chosen between roughly 4 and 12 mm depending on bushing size. Layout and coverage calculations are covered in calculating plug size for graphite-plugged bronze bearings; general construction and size coverage are described under graphite-plugged bronze bushings.
On a flanged bushing the flange face itself is frequently the part that runs dry under load, so the thrust face can be plugged as well. Some points worth putting on the drawing:
- Whether the flange face, the bore, or both carry plugs.
- Whether plugs must stop short of the bore edges, which is often required when a seal runs against the face.
- Operating temperature. Plugged bronze commonly runs from about −40 °C (−40 °F) up to 250 °C (480 °F), with some bases usable near 300 °C (570 °F).
- Initial run-in expectation — a short period at reduced load establishes the film more reliably.
When not to choose a flanged bushing
The flange adds material, machining operations and housing requirements. It is not automatically the better part:
- Axial load is negligible. If nothing pushes the bushing out, a plain sleeve costs less and the housing needs only a through bore. A shaft shoulder or external snap ring can handle occasional location.
- Thrust exceeds the flange face capacity. Growing the flange OD has diminishing returns because the alloy still governs. Separate thrust washers or a rolling-element thrust bearing usually solves it more cheaply.
- The housing face cannot be made square to the bore. A flange clamped against a face that is out of square is bent into the bore and the two bearing lands lose alignment.
- No room for counterbore or fillet relief. Without it, the flange seats on its own fillet rather than its face.
- Radial space is tight. Wrapped thin-wall products suit this; a machined integral flange needs material thickness to exist at all. Examples of the wrapped form in service are on the wrapped bronze bushings in crane applications page.
- High surface speed. Sliding bronze has a PV ceiling; above it, rolling bearings are the correct answer regardless of flange form.
- Access is only from one end and the part is very long. Split or half bushings replace in place without dismantling the shaft.
Checklist before ordering
- Geometry — ID, OD, overall length, flange OD, flange thickness, fillet radius, any bolt holes or trimming.
- Load case — radial load, axial load, direction of the axial load, speed or oscillation angle, duty cycle.
- Environment — temperature range, presence of water, chemicals or abrasive dust, whether any external lubrication is possible.
- Mating parts — shaft material and hardness, surface finish, housing material and bore tolerance.
- Alloy and lubrication — solid bronze, or graphite-plugged and where the plugs sit.
- Tolerances — whether the bore is finished before or after pressing, and which clearance is required in service.
- Quantity and destination — prototype quantity, repeat order quantity, and delivery destination for packaging and freight planning.
What to send for a quotation. Bore diameter, outside diameter and length; flange diameter and thickness; material if known, otherwise the operating conditions — load, speed or oscillation angle, temperature and medium; tolerances or the fit you need; quantity for first order and for repeats; and the delivery destination so freight and packing can be quoted correctly. A drawing or sample part number is always helpful.
Send these details to una@viiplus.com and we will confirm the flange form, propose a material with numbers, and quote against the drawing.
Self Lubricating Oil Free Bushing Flanged Bearing
Flange Bearings: Variety of Sizes: Available in sizes like 1/4″ x 3/8″ x 15/32″, 1/2″ x 3/4″ x 15/16″, and more, with varying flange thicknesses and diameters.
Material Composition: Typically made from sintered bronze or cast brass, providing durability and self-lubrication capabilities.
Oil Filled Flanged Bronze Bearings: Operating Temperatures: Can operate in temperatures ranging from 10°F to 220°F, suitable for various environments.
Oil Impregnation: Bushings are oil-impregnated for lubrication and corrosion resistance, enhancing performance and longevity.
Metric Sizes Available: Metric bronze bushings can be provided upon request for applications requiring non-standard dimensions.
Frequently Asked Questions (FAQs)
Send the dimensions or the drawing
Email the bore, outside diameter, length, flange diameter and thickness, together with load, speed, temperature and quantity. We will confirm whether a flanged bushing is the right form, flag any housing changes it requires, and quote to your drawing.
