CuSn8 Flanged Wrapped Bronze Bushing with Lubrication Holes
CuSn8 Flanged Wrapped Bronze Bushing with Lubrication Holes
High-Performance Self-Lubricating Bronze Bushing Solutions & Technologies. Minimize downtime, extend service life, and reduce costs for dynamic applications.
FB092F CuSn8 Flanged Wrapped Bronze Bushing with Lubrication Holes
Application Position Matrix and Material Selection for Mining Drilling & Blasting Equipment
Reference part: FB092F 240 × 245 / 275 × 90 mm · Material: CuSn8 (EN CW453K / DIN 2.1030 / UNS C52100)
0 · Executive summary
Four points
- This part belongs to low-speed oscillating pivot joints — not to rotating shafts. At a 240 mm bore, the allowed PV of a wrapped bronze bushing (2.8 N/mm²·m/s) limits the speed to roughly 5.6 r/min when carrying the full dynamic load of 40 N/mm². Boom pivots, cylinder clevises, track frame oscillation pins and outrigger joints are its correct positions. Do not place it on a rotation head, hose reel, auger or guide roller and expect it to survive continuous rotation.
- Material positioning: CuSn8 is the cost-effective solution for surface-duty, medium-to-heavy oscillating pivots. A 2.5 mm wall saves space, the oil pockets or through holes hold grease, and the alloy resists dust, shock and ordinary atmospheric exposure. Its corrosion performance in acid mine water and seawater is weaker than aluminium bronze — for underground positions with wet, acid water and poor service access, specify aluminium bronze (CuAl10Ni5Fe4 / C95400 family) or a graphite-plugged maintenance-free design instead.
- Red line: copper alloys must not come into direct contact with ammonium nitrate or emulsion matrix. On bulk explosive mixing and charging trucks, the auger, metering pump, product-path seals and hose guide zones must use stainless steel, cast iron or non-metallic composite components, or be physically isolated. This is a safety constraint, not a selection preference.
- 240 mm is a non-standard bore. The standard large-diameter steps of this wrapped series are 200 / 225 / 250 / 265 / 285 / 300. The part must be rolled to drawing as a custom item, with additional controls on press-fit bore contraction, roundness and the position of the rolled seam.
1 · Designation and dimensional anatomy
| Code element | Meaning |
|---|---|
| FB | Wrapped (thin-wall rolled) plain bearing produced from bronze strip |
| 090 / 092 | Running-surface pattern: 090 = diamond lubrication pockets; 092 = through lubrication holes. Both share the same dimensional series. |
| F (suffix) | Flanged (turned-out lip); provides axial location and takes a limited axial load |
| Equivalent naming | Cross-reference by three factors only — dimensions, material and surface pattern. Do not cross-reference by letter codes alone, as supplier prefixes differ. |
| Item | Value | Note |
|---|---|---|
| Bore d | 240 mm | Verify H9 after press fitting; the blank bore must include a contraction allowance to confirm |
| Outer diameter D | 245 mm | Fits an H7 housing bore; the interference must be confirmed by the supplier against the drawing |
| Flange outer diameter Df | 275 mm | 15 mm overhang per side, consistent with the large-bore steps of this series |
| Width L | 90 mm | Standard width for this series at large bore; projected area = 240 × 90 |
| Wall thickness s | 2.5 mm | Common wall for this series at d ≥ 50 mm |
| Flange thickness | ≈ 2.5 mm | Axial capacity of the flange is governed by bending of this plate thickness and cannot be derived from the static pressure rating |
| Projected bearing area | 21 600 mm² | d × L |
| Flange ring area | 12 252 mm² | π/4 × (Df² − D²) |
| Theoretical mass | ≈ 1.78 kg | At 8.8 g/cm³ with uniform wall: body 1.51 kg + flange 0.27 kg estimate |
| Material | CuSn8 | CuSn8P rolled strip, EN CW453K / DIN 2.1030 / UNS C52100 |
Two sizing questions to settle before quoting
- 240 is not a standard step. The standard large-bore steps are 200 / 225 / 250 / 265 / 285 / 300. If the equipment shaft can accept a 250 mm bore, using the standard step removes tooling cost and shortens lead time. If the machine is already designed around 240, the part is rolled as a custom item.
- A 2.5 mm wall on a 240 mm bore is a thin-wall, large-bore part. The bore contracts after press fitting and roundness is sensitive to wall thickness. Controls: housing bore H7 with roundness within IT8, housing surface roughness Ra ≤ 3.2, housing chamfer ≥ 1.5 × 15°, installation with a guided mandrel, and post-fit verification of bore size to H9 and of roundness.
2 · Material card: CuSn8 wrapped bushing
2.1 Chemical composition (wt%, EN CW453K)
| Cu | Sn | P | Zn | Fe | Ni | Pb |
|---|---|---|---|---|---|---|
| Balance | 7.5 – 8.5 | 0.01 – 0.40 | ≤ 0.20 | ≤ 0.10 | ≤ 0.20 | ≤ 0.02 |
Wrapped bushings commonly use the CuSn8P grade (P 0.2 – 0.4), which balances strength and formability. Incoming material is verified against the mill certificate (EN 10204 3.1). The alloy is RoHS and ELV compatible.
2.2 Physical and mechanical properties (strip condition dependent)
| Physical property | Value |
|---|---|
| Density | 8.8 g/cm³ |
| Melting range | 900 – 1050 °C |
| Thermal conductivity | 67 W/(m·K) |
| Modulus of elasticity | 115 GPa |
| Thermal expansion (20–300 °C) | 18.5 ×10⁻⁶/K |
| Electrical conductivity | ≥ 13 % IACS |
| Mechanical property | Range |
|---|---|
| Tensile strength Rm | 370 – 630 MPa |
| Yield strength Rp0.2 | 250 – 460 MPa |
| Hardness | 90 – 200 HV |
| Elongation A | 13 – 50 % |
| Common supply tempers | R450 / R540 |
| Corrosion behaviour | Good, incl. seawater |
The cold-worked temper of the strip determines the strength and hardness band (R370 increasing to R740 in strength, decreasing in ductility). The temper should be specified on the drawing — otherwise the same nominal “CuSn8” can deliver a load capability that differs by nearly a factor of two.
2.3 Allowable working limits of a wrapped bushing (grease lubrication)
| Parameter | Grease | Oil | Note |
|---|---|---|---|
| Allowable static load | 120 N/mm² | ≤ 140 N/mm² | Shock cases must be evaluated on peak load |
| Allowable dynamic load | 40 N/mm² | 40 – 70 N/mm² | Linked to speed, see 2.4 |
| Allowable sliding speed v | 2.5 m/s | ≤ 10 m/s | Large-bore parts are PV limited and never reach this figure |
| Allowable PV | 2.8 N/mm²·m/s | 10 – 16 N/mm²·m/s | The governing limit for large-bore parts |
| Friction coefficient (lubricated) | 0.05 – 0.25 | 0.05 – 0.15 | — |
| Operating temperature | −40 … +200 °C | Supplier data sheets quote wider bands; the practical limit is set by the grease to confirm | |
| Housing tolerance | H7 | Verify bore to H9 after fitting | |
| Shaft tolerance | f7 – f8 (or h6) | f7/f8 is preferred for oscillating pivots | |
| Shaft surface roughness Ra | ≤ 0.8 µm | May be relaxed to 1.6 µm for hardened shafts | |
| Shaft hardness | ≥ 200 HB | Data sheets differ, some require ≥ 45–55 HRC or ≥ 300 HB. The requirement must be set from the measured hardness of the actual pin. must clarify | |
2.4 The real ceiling for large-bore parts: PV and speed
An allowable PV of 2.8 N/mm²·m/s means that the higher the load, the lower the permitted speed. For d = 240 mm, using v = πdn/60 with n in r/min:
| Specific load p (N/mm²) | Corresponding radial load (kN) | Allowable v (m/s) | Allowable speed n (r/min) | Application verdict |
|---|---|---|---|---|
| 40 (dynamic limit) | 864 | 0.070 | 5.6 | Oscillating pivot, intermittent motion |
| 25 | 540 | 0.112 | 8.9 | Slow oscillation, luffing |
| 10 | 216 | 0.280 | 22.3 | Low-speed rotation may be considered |
| 5 | 108 | 0.560 | 44.6 | Light-duty rotation |
Conclusion: this size belongs on pivot joints, oscillating motion and intermittent duty. If it is placed on a continuous rotation position (auger, reel, guide roller) and the speed exceeds roughly ten r/min, the position must be re-evaluated with a thick-wall cast tin bronze, an aluminium bronze or a steel-backed bimetal bushing.
3 · Application position matrix
The matrix follows the three-stage mining service chain: drilling → blasting → service and rental. In the type column, FB092F is the reference part (flanged, lubrication holes, wrapped), FB090 is the plain wrapped bushing with diamond pockets, and plugged denotes a graphite-plugged self-lubricating design.
| # | Unit | Position | Motion | Load | Environment | Type | Material | Key control point |
|---|---|---|---|---|---|---|---|---|
| A · Surface drilling — top hammer, DTH and rotary blast hole rigs | ||||||||
| A1 | Crawler undercarriage | Track frame oscillation pin / equaliser beam pivot | Oscillating ±5–8° | Heavy + shock | Dust, slurry, rain | FB092F (large bore) | CuSn8 wrapped | Use thick-wall aluminium bronze for very steep shock spectra; the flange is for location only — thrust is taken by retaining rings |
| A2 | Crawler undercarriage | Idler and track tensioner support | Low-speed rotation | Medium-heavy | Heavy abrasive | FB090 plain | CuSn8 wrapped | Dust sealing is essential; abrasive ingress is the dominant failure mode |
| A3 | Levelling | Outrigger / jack cylinder clevis | Oscillating | Medium | Dust | FB092F | CuSn8 | Flange carries axial location, installation needs no adjustment |
| A4 | Boom | Boom root pivot — typical position for this part | Oscillating ±20–40° | Heavy + shock | Dust | FB092F 240×245/275×90 | CuSn8 | Verify bore H9 after fitting; re-check clearance against thermal expansion; grease interval 250 h |
| A5 | Boom | Lift and pitch cylinder clevis | Oscillating | Heavy | Dust | FB092F | CuSn8 | Misalignment between cylinder eyes causes edge loading and spalling |
| A6 | Boom | Swing cylinder pivot / boom rotation joint | Oscillating + rotating | Heavy | Dust | FB092F | CuSn8 / Al bronze | Where a rotating component is present, check PV first (see 2.4) |
| A7 | Feed system | Feed beam luffing pivot / mast saddle | Oscillating | Heavy | Dust | Thick-wall Al bronze | CuAl10Ni5Fe4 | Luffing pivots often combine edge loading with slow sliding; a thick wall resists edge collapse |
| A8 | Feed system | Rotation head cradle guide bushing | Reciprocating slide | Medium-heavy | Rock dust + water | Plugged / FB090 | Graphite bronze / CuSn8 | Sliding duty with difficult regreasing — prefer maintenance-free design or centralised lubrication |
| A9 | Feed system | Feed chain tensioner and guide roller | Rotating | Medium | Heavy abrasive | FB090 | CuSn8 | Over-tensioning is the main cause of chain side wear; set to the maker’s tension value |
| A10 | Drilling tools | Rod centraliser / guide bushing | Rotating + shock | High shock | Rock dust + water | Al bronze / Ni bronze | CuAl10Ni5Fe4 | Running clearance against the rod: too tight seizes, too loose whips |
| A11 | Drilling tools | Breakout wrench pivot | Oscillating | Medium + shock | Rock dust | FB092F | CuSn8 | Breakout torque reaction is high; the pin must be hardened |
| A12 | Drilling tools | Rod handler / rod magazine pivot | Oscillating + rotating | Medium | Dust | FB090F | CuSn8 | Positioning accuracy drives coupling success; tighten the upper clearance limit |
| A13 | Dust control | Dust hood / ducting pivot | Oscillating | Light | Heavy dust | FB090 / composite | CuSn8 / composite | Light-duty positions can use composite bushings to reduce cost |
| B · Underground drilling — development jumbos, long-hole rigs, roof bolters | ||||||||
| B1 | Jumbo | Boom, intermediate arm and pitch cylinder pivots | Oscillating | Heavy + shock | Wet, acid water, dust | Thick-wall Al bronze | CuAl10Ni5Fe4 / C95400 | Underground, corrosion resistance outranks cost; thin-wall CuSn8 is not the first choice in acid water |
| B2 | Jumbo | Feed swing and rotation joint | Oscillating / rotating | Heavy | Wet | Thick-wall Al bronze | CuAl10Ni5Fe4 | As above; add guards to limit water impingement |
| B3 | Jumbo | Rock drill mounting and damper bushing | High-frequency shock | Very high shock | Water + rock dust | Al bronze / bimetal | CuAl10Ni5Fe4 / steel-backed | Select on the shock spectrum, not on static load; assess damping and preload |
| B4 | Jumbo | Cable and water hose reel shaft | Rotating | Light-medium | Wet | Plugged / FB090 | Graphite bronze / CuSn8 | Regreasing is difficult underground; prefer maintenance-free |
| B5 | Roof bolter | Magazine, feed and positioning pivots | Oscillating | Medium | Dust + water | FB092F | CuSn8 | Same logic as A11/A12; sharing sizes across positions reduces stock variety |
| B6 | Long-hole rig | Rod stabiliser guide | Rotating | Medium | Rock dust + water | Al bronze / plugged | CuAl10Ni5Fe4 / graphite bronze | Rod changes are frequent; wear life directly sets downtime cost |
| C · Blasting operations — bulk mixing and charging trucks, detonator transport | ||||||||
| C1 | Bulk mixing / charging truck | Auger and metering pump bearing seats | Rotating | Medium | Ammonium nitrate / emulsion matrix | Copper alloys not permitted | Stainless steel / cast iron / non-metallic composite | Red line: copper and ammonium nitrate are incompatible (risk of sensitive compound formation and accelerated decomposition). The product path must be non-copper; see section 6 |
| C2 | Bulk mixing truck | Hydraulic arm and hopper pivots, away from the product path | Oscillating | Medium | Dust | FB092F | CuSn8 + isolation | must clarify Confirm the pivot has no cross-connection with the product path and that grease or dust cannot migrate back into it |
| C3 | Charging truck | Charging hose reel and guide roller | Rotating | Light | Dust | Non-copper preferred | Composite / stainless bush | Adjacent to the product path; treat under the C1 rule |
| C4 | Detonator transport | Transport box hinge and latch | Oscillating | Light | Dust | FB090 | CuSn8 | No ammonium nitrate contact, copper alloy is acceptable; observe anti-static and earthing requirements |
| C5 | DTH rig | DTH feed slide guide | Reciprocating slide | Medium | Rock dust | Plugged / FB090 | Graphite bronze | Wear resistance and dust exclusion matter equally in this position |
| D · Service, rental and asset management | ||||||||
| D1 | Overhaul | Recovery of a worn housing bore (pin unworn) | — | — | — | Oversize OD or housing sleeve | CuSn8 / CuAl10Ni5Fe4 | Where the housing is oval, sleeve it and press a standard part rather than ordering a one-off that extends lead time |
| D2 | Rental fleet | Maintenance-free priority positions | Oscillating | Medium | Hard to reach | Plugged | Graphite bronze | Offset the higher unit price against one avoided shutdown, calculated on fleet hours |
| D3 | Asset management | Replacement criteria and inspection baseline | — | — | — | — | — | Criteria: clearance at 1.5–2 × original design, exposed base metal or copper smearing, localised temperature rise, flange collapse or rolled edge |
4 · Selection logic
- Motion first, material second. Oscillating pivot → thin-wall wrapped bronze. Continuous rotation → check PV and speed before considering thick-wall cast or bimetal parts. Reciprocating slide → prefer a self-lubricating plugged design.
- Then environment. Dry surface dust → wrapped CuSn8 is adequate. Underground wet or acid water, or seawater → aluminium bronze family. High temperature or water wash → re-check grease and guarding.
- Then service access. Accessible with an inspection routine → wrapped bronze with periodic greasing. Inaccessible or very costly downtime → graphite-plugged maintenance-free.
- Then the counterface. Pin hardness, roughness and roundness set bushing life. If the pin is out of specification, hardening or replacing the pin delivers more than changing the bushing grade.
- Then the geometry. Axial location or small thrust → flanged (F). Radial load only → a plain bushing is more economical.
- Then the red-line filter. Any position in contact with ammonium nitrate or emulsion matrix is excluded from copper alloys regardless of how well the load matches.
Candidate material comparison
| Candidate | Dynamic load reference | Advantages | Limitations | Typical mining position |
|---|---|---|---|---|
| CuSn8 wrapped CW453K · FB090 / 092 / 092F |
40 N/mm² | Thin wall saves space and material, resists dust and shock, cost controlled, custom large bores available | Requires lubrication; low speed ceiling at large bore; not the strongest choice in acid water | Boom and cylinder pivots, outriggers, track frame oscillation pins |
| Cast tin bronze CuSn10 / CuSn12 · C93200 family |
Higher than wrapped | High capacity in a thick wall, can be re-machined, tolerant of slow heavy duty | Higher mass and cost, larger envelope | Heavy rotating supports, reels, large tonnage pivots |
| Aluminium / nickel aluminium bronze CuAl10Ni5Fe4 · C95400 / C95500 |
High, shock resistant | Corrosion resistant including seawater and acid water, resistant to impact fatigue and seizure | Higher cost, demanding counterface hardness requirement, moderate machinability | Underground jumbo pivots, rock drill mountings, rod stabilisers |
| Steel-backed bimetal | High | Very high load stiffness, suited to large shock loads and tight envelopes | Sensitive to housing roundness and press-fit process; cannot be re-machined | Rock drill mountings, heavy-duty cylinder eyes |
| Graphite-plugged bronze | Medium, maintenance-free | No regreasing, resists seizure in dusty conditions, suited to hard-to-reach positions | Lower speed and PV limits; higher unit price than wrapped bushings | Underground reels, rotation head cradles, elevated pivots |
| Non-copper option for ammonium nitrate service |
— | Complies with ammonium nitrate compatibility requirements | Weaker self-lubricating behaviour than copper-based alloys; requires a dedicated lubrication design | Bulk truck auger and pump seats, charging hose guides |
5 · Mapping to the three service pillars
| Pillar | Where this component fits |
|---|---|
| Equipment service and support | Pivot bushings are a recurring source of unplanned downtime. A position-coded bushing list with grease intervals and replacement criteria shifts maintenance from break-down repair to scheduled replacement by operating hours. |
| Parts supply and equipment rental | Rental fleets cannot afford to wait for a part in a remote location. Build consignment stock for high-frequency positions (A4, A5, A11, A12), giving priority to sizes shared across machine types, and trade stock turnover for fleet availability. |
| Engineering and asset management | Keep a part number / material / life / cost register by position, and take replacement decisions on cost per operating hour rather than purchase price. This register directly supports overhaul and retirement decisions. |
6 · Red lines
Red line 1 Ammonium nitrate and emulsion matrix compatibility
Ammonium nitrate is a known incompatible combination with copper, zinc, lead and their alloys, with a risk of sensitive compound formation and accelerated decomposition. On bulk mixing and charging trucks, the auger, metering pump, product-path seals and hose guide zones must not use copper alloy bushings; specify stainless steel, cast iron or non-metallic composite components, or provide physical isolation with an explicit “no direct contact” requirement. This constraint must not be waived on the grounds that the load rating fits, until it has been confirmed in writing with the customer’s safety and engineering functions.
Red line 2 The flange is not a thrust bearing
The flange thickness of this part is approximately 2.5 mm and its axial capacity is governed by plate bending. The flange provides axial location and takes only limited thrust; it must not be designed against a thrust value derived from the static pressure rating. Where axial loads are significant, transfer them to an end face, a retaining ring or a thrust washer, or move to a thick-wall cast part with an integral flange.
Red line 3 Counterface pin hardness and finish
Bushing life is set by the mating component. Published requirements for shaft hardness range from ≥ 200 HB to ≥ 45–55 HRC, a difference of several times, so the requirement must be set from the measured hardness of the actual pin and not defaulted to the lower value when quoting. A shaft roughness of Ra ≤ 0.8 µm and satisfactory roundness are equally mandatory.
7 · Technical clarification checklist
Recommended for issue together with the quotation. Final material and tolerance selection follows the returned information. Printable and tick-box ready.
- Position: which pivot of which machine does 240 × 245 / 275 × 90 correspond to (boom root, lift cylinder, track frame oscillation, other)? The load spectrum differs substantially between these.
- Load: maximum radial load at the pivot in kN or t, plus the peak shock load, and whether any axial load is present and at what magnitude.
- Motion: oscillation angle range, cycle frequency or speed in r/min, and stroke time.
- Pin: material, measured surface hardness in HB or HRC, surface roughness Ra, and diameter tolerance.
- Housing: bore tolerance and roundness, surface roughness Ra, housing material and wall thickness, and whether sleeving is possible.
- Environment: surface or underground; acid water or seawater wash; dust concentration; ambient temperature range.
- Lubrication: current method and interval; whether “grease at installation plus periodic regreasing” is acceptable or a maintenance-free solution is required.
- Geometry: whether the flange is used for axial location and whether a plain, unflanged bushing could be accepted at lower cost and shorter lead time.
- Size: whether the bore can move from 240 to the standard step of 250; if not, please provide the drawing for a rolled-to-drawing custom part.
- Safety: whether the position has any connection or return path to an ammonium nitrate or emulsion product line, which decides whether copper alloys may be used at all.
- Life: expected replacement interval in hours or months, acceptable downtime, and the actual life and failure mode of the current part (wear, seizure, collapse, corrosion).
- Volume: first order quantity, annual usage, and whether consignment stock or cross-model standardisation would be useful.
- Documentation: whether a mill certificate to EN 10204 3.1, a dimensional inspection report and bilingual installation and maintenance instructions are required.
8 · Installation, spares and maintenance
- Installation: housing chamfer ≥ 1.5 × 15°, pin chamfer for guidance, press fitting with a guided mandrel, no direct hammering, and a light grease film on the outer surface before pressing. Adhesive must not contact the running surface.
- Initial greasing: the lubrication holes and pockets must be filled with lithium-based extreme pressure grease (NLGI 2) during assembly. This is the precondition for the oil-pocket design to work; an unfilled FB092 behaves as a dry-friction bearing.
- Regreasing interval: typically 250 h or monthly in ordinary dust; shorten to 100–150 h in heavy dust or water wash; follow the centralised lubrication system setting where one is fitted.
- Dust exclusion: fit seals or dust lips at positions exposed to heavy abrasive dust. Abrasive ingress is the main abnormal failure source for wrapped bronze bushings.
- Replacement criteria: clearance reaching 1.5–2 × original design, exposed base metal or copper smearing, localised temperature rise, or flange collapse and rolled edge. Replace on any one of these.
- Stock policy: consolidate sizes across machine types to reduce variety; hold consignment stock for high-frequency positions at three to six months of usage and single-unit stock for low-frequency positions.
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