SAE 841 Oil-Impregnated Sintered Bronze Bearings: Material Data, Operating Limits and Selection Guide
SAE 841 Oil-Impregnated Sintered Bronze Bearings: Material Data, Operating Limits and Selection Guide
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Powder Metallurgy Bearing Materials · Technical Reference
SAE 841 Oil-Impregnated Sintered Bronze Bearings: Material Data, Operating Limits and Selection Guide
SAE 841 is the industry designation for oil-impregnated sintered (powder metallurgy, P/M) bronze of nominal composition 90Cu–10Sn. This reference consolidates the composition, mechanical and physical data, tribological limits, dimensional practice and documentation boundaries that engineers need when screening this material for general industrial plain-bearing duty.
Scope and compliance boundary. This document is material property reference data compiled from published standards and manufacturer datasheets, for general engineering screening only. It does not contain, and must not be read as, any of the following:
- Military or defence qualification — no conclusion on defence-export or dual-use export-control classification, specialty-metal flow-down status, or any defence-standard approval.
- Automotive qualification — no automotive quality-management, production-part-approval or material-data-submission conclusion.
- Food-contact suitability — no conclusion under Regulation (EC) 1935/2004, national food-contact law, or FDA programmes.
- Medical device approval — no conclusion under EU MDR 2017/745, FDA 21 CFR 820 / QMSR, ISO 13485 or ISO 10993.
- Nuclear qualification — no conclusion under ASME BPVC Section III, 10 CFR 50 Appendix B, 10 CFR 21 or RCC-M.
- Aerospace airworthiness certification — no airworthiness release certificate, technical standard authorisation, parts-manufacturer approval, type-certificate or special-process accreditation conclusion. Citation of a material specification here is not an airworthiness release and is not any other certification conclusion.
Qualification for a specific application remains the responsibility of the purchaser and the installing design authority. See Section 10 and the disclaimer.
1. What SAE 841 actually designates
SAE 841 is a legacy commercial designation, not a currently published SAE alloy specification in the J461 / J462 series. In trade it denotes an oil-impregnated sintered bronze of nominal composition 90Cu–10Sn, produced by powder metallurgy. The governing consensus specification is ASTM B438 / B438M, Standard Specification for Bronze-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated). Within that specification, the SAE 841 chemistry and property band correspond to Grade 1, Type 2, which carries the MPIF Standard 35 material code CT-1000-K26.
In the MPIF code system, C denotes a copper base, T denotes tin as the principal alloying element, and the four-digit group gives the nominal percentages of the principal and secondary alloying elements (10 = about 10 % Sn; 00 = no secondary element). The letter K denotes the radial crushing strength constant, and the two digits following it give its minimum value in thousands of psi — so K26 = 26,000 psi minimum radial crushing strength.
| System / region | Designation | Status and remarks |
|---|---|---|
| Trade / legacy (US) | SAE 841 | Commercial designation retained for search and procurement. Not a current SAE J461 / J462 alloy number. |
| ASTM | ASTM B438 / B438M, Grade 1, Type 2 | Active consensus specification. Type number defines the density band (Type 2 = 6.4–6.8 g/cm³); all bearings in this specification are oil-impregnated unless otherwise specified. |
| MPIF | MPIF Standard 35 — CT-1000-K26 | Bronze, low graphite. K26 = 26 × 10³ psi (180 MPa) minimum radial crushing strength. |
| ISO | ISO 5755 — C-T10-K180 | Closest match by K value and density. Note the ISO tin window (8.5–11.0 %) is wider than the MPIF window (9.5–10.5 %), so equivalence is approximate and should be confirmed per order. |
| DIN (Europe) | (per DIN 30910-3 / DIN 1850) | Industry convention widely used in supplier literature; confirm the mapping against the current DIN text before contractual use. |
| China (GB / JB) | CuSn10 sintered bronze; copper-base oil-impregnated P/M bearing | Relevant standards: GB/T 2688-2012 (technical conditions for P/M bearings), GB/T 18323-2001 (sintered bush dimensions and tolerances), JB/T 7381-2010 (determination of limiting PV), JB/T 7380-2010 (water-atomized CuSn10 powder). |
| Legacy cross-reference only | MIL-B-5687D Type 1 Grade 1; SAE AMS 4805 | Historical only. MIL-B-5687D was cancelled in 2008 and superseded by ASTM B438 (bronze-base) and ASTM B439 (iron-base). AMS 4805 has been stabilised by SAE on the grounds that it no longer reflects current technology. Listing these numbers is a historical cross-reference for drawing conversion and carries no military, defence or airworthiness qualification meaning. |
Do not treat SAE 841 as interchangeable with dense bearing bronzes. SAE 660 / UNS C93200 (cast leaded tin bronze, about 83Cu-7Sn-7Pb-3Zn), UNS C90700 (about 89Cu-11Sn) and wrought CuSn8 / UNS C52100 phosphor bronze are fully dense, externally lubricated alloys in the ASTM B505 / B271 / B103 / B139 family. SAE 841 is a porous material. Its tensile strength is roughly one fifth of that of wrought CuSn10 and its elongation is around 1 % instead of tens of percent. Substituting one for the other without redesign changes load capacity, shock resistance and lubrication behaviour.
2. Why the material is selected
The selection case for oil-impregnated sintered bronze rests on four properties that come directly from the manufacturing route.
- Reservoir lubrication. The sintered structure retains about 19–25 % interconnected porosity by volume. After vacuum impregnation the pores act as an oil reservoir that feeds the sliding surface, so within the stated duty range no external lubrication circuit is required. Oil is exuded under load and drawn back by capillary action as the bearing cools.
- Near-net-shape production. Compaction and sintering produce finished or near-finished geometry, so machining is limited to sizing operations. This supports consistent dimensional output in volume production.
- Low friction and quiet running. With an oil film established, published friction coefficients for the material fall in the 0.05–0.20 band, which suits fractional-horsepower motors and office or appliance drives where noise matters.
- Conformability and embeddability. The relatively soft bronze matrix tolerates moderate misalignment and can embed small hard particles, which reduces scoring risk on shafts that are not hardened to rolling-bearing standards.
The corresponding trade-offs are equally clear: strength and ductility are far below those of dense bronze, the material has limited shock resistance, and the service temperature ceiling is set by the impregnating oil rather than by the metal.
3. Material technical data
3.1 Chemical composition
| Element | Requirement | Remarks |
|---|---|---|
| Copper (Cu) | Balance (87.2–90.5) | ASTM-derived minimum is 87.2 %; several distributor datasheets state 87.5 %. Both appear in current trade; use the lower figure for conservative inbound design. |
| Tin (Sn) | 9.5–10.5 | Principal alloying element; consistent across ASTM and manufacturer sources. |
| Graphitic carbon (C) | 0.3 max | Low-graphite bronze grade. A figure of 1.75 % seen on some pages belongs to legacy bronze-lead-graphite grades, not to CT-1000-K26. |
| Iron (Fe) | 1.0 max | Residual. |
| Total other elements | 1.0 max | Some suppliers state 0.5 % max; older printings use 1.2 % by difference. |
| Lead (Pb) | No requirement stated | Lead is not an intentional addition to CT-1000-K26 and no lead requirement appears in the B438 tables for this grade. Leaded bronze-graphite grades are separate materials. For a lead limit on a specific lot, request the inspection document. |
3.2 Physical and mechanical properties
Values apply to the oil-impregnated condition unless stated otherwise. Rows marked standard are requirements of ASTM B438 / MPIF Standard 35; rows marked typical are manufacturer-published indicative values and are not specification minimums.
| Property | Value | Value (SI) | Basis |
|---|---|---|---|
| Density, oil-impregnated | 6.4–6.8 g/cm³ | — | Standard (Type 2 band) |
| Density, pore-free 90/10 bronze | 8.75 g/cm³ | — | Wrought CuSn10 reference, for porosity comparison |
| Oil content, minimum | 19 vol % | — | Standard (Type 2) |
| Oil content, typical reported | 18–25 vol % | — | Typical |
| Interconnected porosity | approx. 19–25 % | — | Typical |
| Radial crushing strength K, minimum | 26,000 psi | 180 MPa | Standard, ASTM B939 test method |
| Tensile strength | approx. 14,000 psi | approx. 97 MPa | Typical |
| Compressive yield strength | approx. 11,000 psi | approx. 76 MPa | Typical |
| Elongation | approx. 1 % in 1 in | — | Typical |
| Apparent hardness | HRH 45 as-sintered (45–70 range reported) | — | Typical, apparent value on a porous surface |
| Coefficient of thermal expansion | approx. 18 × 10⁻⁶ /℃ | 10 × 10⁻⁶ /℉ | Typical |
| Thermal conductivity | approx. 22 W/m·K measured on porous bronze; 50 W/m·K for wrought CuSn10 | — | Single measured study (porous) and wrought datasheet |
| Friction coefficient, oil-lubricated | 0.05–0.20 | — | Typical, depends on load, speed and film state |
| Young’s modulus | Not established for the porous grade | — | Wrought CuSn10 is about 110 GPa; do not apply to porous material without test data |
Porosity effect. The interconnected pore network that provides the oil reservoir also cuts the load-bearing cross-section. Published tensile values for wrought CuSn10 are roughly 400–500 MPa with elongation above 50 %, against about 97 MPa and 1 % for the sintered grade. Design stresses must be taken from porous-material data, not from wrought-bronze datasheets.
Radial crushing strength. The acceptance relationship in ASTM B438 is P = K · L · t² / (D − t), where P is the breaking load, K the radial crushing strength constant, L the bearing length, t the wall thickness and D the outside diameter. This governs press-fit and sizing calculations rather than running load capacity.
3.3 Operating limits
| Parameter | Commonly published value | SI equivalent | Note |
|---|---|---|---|
| PV limit | 50,000 psi·ft/min | approx. 1.75 MPa·m/s | European datasheets commonly publish 1.6–1.8 N/mm²·m/s. Use the lower bound for screening. |
| Static load limit | 8,000 psi | approx. 55 MPa | Some European sources publish 20–50 N/mm²; confirm against the specific grade and density. |
| Dynamic load limit | 2,000 psi | approx. 14 MPa | European sources publish 10–14 N/mm². |
| Sliding speed limit | 1,200 ft/min | approx. 6.1 m/s | European sources publish 5–6 m/s. |
| Service temperature, standard mineral oil | approx. 10 to 220 ℉ | approx. −12 to +105 ℃ | Set by the oil. One manufacturer lists 225 ℉ (107 ℃) as the continuous maximum. |
| Service temperature, wide-range synthetic oil | approx. −35 to +300 ℉ | approx. −37 to +150 ℃ | Requires the synthetic impregnation to be specified at order stage. |
The limits above are screening values for clean, dry, room-temperature industrial duty with a hardened and ground steel shaft and a rigid housing. Duty cycle, contamination, shaft finish, housing stiffness and ventilation shift them substantially. Confirm against the supplier’s current datasheet and, where the application is load-critical, against bench test data.
4. Manufacturing route, forms and dimensional practice
The production sequence is powder blending (elemental copper and tin, or prealloyed powder) → compaction at roughly 200–700 MPa → sintering at about 780–870 ℃ in a reducing atmosphere to produce an essentially alpha-bronze structure → sizing or coining to bring the bore to tolerance and improve surface finish → vacuum oil impregnation → final inspection.
| Form | Typical use | Notes |
|---|---|---|
| Cylindrical sleeve bushing | General radial bearing duty | The standard catalogue form; also called a plain or journal bushing. |
| Flanged bushing | Radial plus light axial location | Flange takes thrust on one face; check that the flange root can carry the axial load. |
| Thrust washer | Axial location only | Supplied flat or with oil-distribution grooves. |
| Spherical / self-aligning bushing | Housings with shaft misalignment | Outer spherical surface seats in a matched bore. |
| Plate and strip | Slideways, wear plates | Supplied by thickness; further machining by the user. |
| Solid and cored bar stock | Prototypes, low volume, large diameters | Cored bar reduces machining volume. Machining closes surface pores on cut faces, so re-impregnation is advisable after machining. |
Machining caution. Conventional machining of oil-impregnated bronze requires sharp carbide tools and light cuts. Reaming, honing or grinding of the bore is generally discouraged, because the tool smears metal across the surface and closes the interconnected pores that supply oil to the sliding interface. Where final bore accuracy is required, grinding or burnishing after impregnation and subsequent re-impregnation is the usual approach; confirm the sequence with the supplier.
5. Application matrix
The matrix below covers general industrial equipment. It deliberately excludes defence, in-vehicle safety systems, food-contact zones, medical devices, nuclear island equipment and certified aircraft installations, for which separate qualification applies (see Section 10).
| Equipment | Bearing position | Duty | Load / speed band | Environment | Form |
|---|---|---|---|---|---|
| Fractional-horsepower and fan motors | End-shield and through-bolt journals | Continuous rotation, light load | Low load, moderate speed | Dry, indoor, up to motor winding temperature | Sleeve or spherical |
| Circulator and small water pumps | Impeller shaft, motor journal | Continuous, occasional wet exposure | Low to moderate load | Humid; splash possible | Sleeve; stainless shaft recommended |
| Conveyors and material handling | Idler rolls, guide rollers, pivot points | Continuous or intermittent, dusty | Moderate load, low speed | Dust and abrasive fines | Sleeve or flanged; seals advisable |
| Office and business machines | Paper-feed rollers, carriage guides | Intermittent, start/stop | Light load, low speed | Clean indoor, paper dust | Sleeve, thrust washer |
| Household appliances | Drum supports, hinge pivots, agitator shafts | Intermittent, variable speed | Light to moderate load | Dry or humid, moderate temperature | Sleeve, flange, spherical |
| Power tools and garden equipment | Gearbox journals, linkage pivots | Intermittent, shock loading | Moderate load, moderate speed | Dusty, outdoor | Sleeve or flanged; check shock margin |
| Textile machinery | Roller journals, take-up shafts | Continuous, lint-laden | Light load, moderate speed | Lint, oil mist | Sleeve, flange |
| Packaging and printing machines | Idler and impression-cylinder journals | Continuous, cyclic load | Moderate load, moderate speed | Clean to dusty indoor | Sleeve or flange |
| Vending machines and access control | Latch pivots, delivery-mechanism shafts | Intermittent, low duty | Light load, low speed | Indoor, wide temperature swing | Sleeve, thrust washer |
| Exercise and leisure equipment | Pulley axles, pivot joints | Intermittent, oscillating | Light to moderate load | Indoor, perspiration exposure possible | Sleeve or flange; corrosion check on the shaft pairing |
6. Selection guide
| If the duty is | Direction | Reason |
|---|---|---|
| Light load with continuous rotation and no relubrication access | SAE 841 / CT-1000-K26 sleeve bushing | The oil reservoir supports the duty without an external lubrication circuit. |
| Light load with occasional relubrication possible | SAE 841 with relubrication provision | Periodic replenishment extends the duty envelope at elevated temperature. |
| Higher load at the same speed | Higher-density bronze grade in the same family (higher K value), or a bronze-graphite grade | Greater density raises crushing strength and load capacity. |
| Boundary lubrication, oscillating or pulsating load | Graphite-bearing bronze grade, or a PTFE-modified impregnation | Solid lubricant content supports film formation where hydrodynamic oil films do not establish. |
| Continuous temperature above about 100 ℃ | Specify synthetic high-temperature impregnation, or move to a material not limited by oil | Standard mineral oil oxidises, sweats out and forms varnish that blocks pores. |
| High load combined with high speed | Do not select a porous bronze bushing; consider a dense wrapped bronze bushing or a rolling bearing | The PV limit of oil-impregnated bronze is the governing constraint. |
| Shock or impact loading | Do not select a porous bronze bushing without testing; consider dense cast bronze | Elongation of about 1 % gives limited energy absorption. |
| Submerged or washdown service | Do not select standard oil-impregnated bronze without testing | Water displaces and washes out the oil; confirm the arrangement with the supplier. |
7. Variant comparison
| Variant | Composition / structure | Relative load capacity | Temperature ceiling driver | Typical selection reason |
|---|---|---|---|---|
| SAE 841 / CT-1000-K26 (this material) | 90Cu–10Sn, low graphite, about 19–25 % interconnected porosity, mineral oil | Baseline | Impregnating oil | General light-duty radial bearing with no external lubrication |
| Higher-density bronze grades (higher K) | Same family, increased density after sizing or double press and sinter | Above baseline | Impregnating oil | Higher press-fit and load requirement at the same geometry |
| Bronze-graphite grades | Cu–Sn with added graphite | Below baseline in strength, more tolerant of boundary lubrication | Impregnating oil and graphite | Oscillating motion, marginal lubrication, start/stop duty |
| Bronze-lead-graphite grades | Cu–Sn–Pb with graphite | Lower | Impregnating oil; lead content affects substance compliance | Applications still specified to legacy drawings that call for leaded material; check the ELV exemption status |
| Iron-base P/M bearings (ASTM B439) | Iron or iron-copper, oil impregnated | Above baseline in strength | Impregnating oil | Cost-sensitive duty where corrosion resistance is not required |
| Wrapped dense bronze bushing (CuSn8 family) | Wrought CuSn8, fully dense, lubricating pockets or holes | Well above baseline | Bronze matrix and grease | Higher load and shock, with periodic external lubrication |
| Cast bronze bushing (for example C93200) | Cast leaded tin bronze, fully dense | Well above baseline | Bronze matrix and grease | Heavy duty, low speed, externally lubricated |
8. Fits, installation, maintenance and replacement
8.1 Shaft and housing practice
| Item | Commonly published practice | Remarks |
|---|---|---|
| Housing bore | H7 | Rigid housing required so that press-fit interference is absorbed predictably. |
| Shaft tolerance | f7 (some suppliers allow f7 to h8) | Combined with the bushing tolerance to give the running clearance. |
| Bushing as supplied (ISO 2795 series) | Inside diameter G7, outside diameter s7, length js13, concentricity IT8 to IT10 | After correct installation in an H7 housing the finished bore is typically H7 or H8. |
| Shaft surface roughness | Ra 0.2 to 0.6 µm depending on supplier guidance; Rz 4 µm is quoted by one source | A smoother shaft reduces wear and oil loss; confirm the value with the supplier for the duty. |
| Shaft hardness | Typically above 200 HB; design guidance for demanding duty quotes 50 HRC and above | Hardened and ground carbon or alloy steel is the usual pairing. |
| Shaft material with stainless, hard chrome or nickel plating | Use an MoS₂-additivated oil | Reduces seizure risk against plated or stainless counterfaces. |
8.2 Press fit, clearance and bore closure
The figures below are indicative values extracted from published engineering catalogue material and should be confirmed against the supplier’s current catalogue before release to production.
| Shaft or outside diameter | Press-fit interference (diametral) | Running clearance — near PV limit | Running clearance — normal duty | Running clearance — light duty |
|---|---|---|---|---|
| 1 in (25 mm) | 0.003 in (0.076 mm) | 0.0015 in (0.038 mm) | 0.0012 in (0.030 mm) | 0.0008 in (0.020 mm) |
| 2 in (50 mm) | 0.004 in (0.102 mm) | 0.0045 in (0.114 mm) | 0.0035 in (0.089 mm) | 0.0018 in (0.046 mm) |
| 3 in (75 mm) | 0.005 in (0.127 mm) | 0.0065 in (0.165 mm) | 0.0055 in (0.140 mm) | 0.0028 in (0.071 mm) |
| 5 in (125 mm) | 0.007 in (0.178 mm) | 0.0085 in (0.216 mm) | 0.0075 in (0.191 mm) | 0.0042 in (0.107 mm) |
Wall thickness and bore closure. Part of the press-fit interference closes the bore. The proportion transmitted to the bore depends on the ratio of wall thickness to outside diameter: thin walls transmit most of the interference to the bore, thick walls absorb more of it. Published catalogue data for a 1 in outside diameter shows roughly 98 % transmission at a 1/32 in wall, about 90 % at 1/8 in and about 50 % at 1/4 in. This is why the bore is normally sized after installation, or the assembled clearance is verified with a fitting pin.
8.3 Installation, relubrication and storage
- Installation. Press the bushing in with an arbor press and a fitting mandrel so that the force is taken on the outer diameter. Do not hammer directly on the bushing end face, and do not press on the flange root.
- Do not ream or hone the bore after installation unless the supplier’s process explicitly includes it, because the operation closes the surface pores.
- Impregnating oil. The standard impregnant is a high-viscosity-index mineral oil of about SAE 30 / ISO VG 68 grade with antioxidant, anti-rust and defoamant additives; some bar stock is impregnated with an ISO VG 100 R&O turbine oil. Low-viscosity oils suit low temperature, high speed and light load; higher-viscosity oils suit higher temperature, slow speed and heavier load.
- Re-impregnation. A published procedure is immersion in ISO VG 68 or VG 150 (SAE 30 / SAE 40) mineral oil held at about 60–70 ℃ for 10–15 minutes, followed by cooling in cold oil. Confirm the oil grade and cycle with the supplier, particularly for synthetic impregnations.
- Storage. Keep bushings in a non-absorbent, sealed container at room temperature, away from direct heat and sunlight. Cardboard packaging draws oil out of the pores. Re-impregnate after prolonged storage.
8.4 Symptom and action
| Observed | Likely cause | Action |
|---|---|---|
| Rapid temperature rise at start-up | Running clearance too small after bore closure, or shaft roughness above the recommended value | Verify assembled clearance with a fitting pin; check shaft Ra; confirm wall thickness against the bore-closure data |
| Dry, dark deposit in the bore | Oil oxidation from operation above the oil temperature limit | Reduce temperature, improve ventilation, or specify a high-temperature synthetic impregnation |
| Oil film on the housing exterior | Oil sweating out under elevated temperature, or over-impregnation | Check operating temperature and duty; consider a higher-viscosity impregnant |
| Scoring of the shaft | Contamination ingress, shaft hardness below the recommended value, or oil depletion | Add sealing, increase shaft hardness, establish a relubrication or re-impregnation interval |
| Premature bore wear | PV above the material limit, or marginal lubrication under oscillating motion | Recalculate PV; consider a graphite-bearing grade or a PTFE-modified impregnation |
| Noise or stick-slip | Clearance too large, misalignment, or oil starvation | Check clearance and alignment; confirm the oil is still present in the pore network |
8.5 Replacement criteria
- Measured bore wear has reached the clearance limit for the application, or the diametral clearance has increased beyond about twice the initial value.
- Visible scoring, cracking or spalling of the bore surface.
- The bore shows a dry, varnished or carbonised appearance indicating oil depletion.
- Shaft wear is measurable; the shaft is usually the more expensive component and the pairing should be assessed together.
- Operating temperature at the bearing is consistently above the limit for the impregnating oil.
9. Engineering checklist
- Essential: Confirm the specification on the drawing as ASTM B438 / B438M Grade 1 Type 2 (or MPIF CT-1000-K26), not merely “SAE 841”, so that density, oil content and K value are all defined.
- Essential: Calculate PV from the actual load and speed and compare it with the material limit using the lower published bound, not the higher one.
- Essential: Confirm the operating temperature against the impregnating oil, and specify synthetic impregnation where the duty exceeds the mineral-oil band.
- Essential: Specify shaft material, hardness and surface roughness on the drawing; the bearing performance depends on the counterface.
- Define whether the bore is to be sized after installation, and state the assembled clearance requirement.
- State the oil type and viscosity grade if the application has a particular temperature or speed profile.
- Request the inspection document type (EN 10204 2.2 or 3.1) at enquiry stage if material verification is required.
- State any substance-compliance requirement (lead content, hazardous-substance restrictions, hazardous-substance communication, substance-information reporting, conflict-minerals reporting) at enquiry stage.
- For any regulated sector — defence, in-vehicle, food contact, medical, nuclear or certified aircraft — obtain the applicable approval through its own route. A material datasheet does not supply it.
- Record press-fit force and assembled bore dimension on first article, because wall thickness drives bore closure.
10. Compliance and documentation boundaries
10.1 Substance compliance
| Regime | Relevance to this material | Status note |
|---|---|---|
| EU restriction of hazardous substances (Directive 2011/65/EU, 2015/863) | Applies to electrical and electronic equipment placed on the EU market, not to a loose bearing in isolation. Compliance is assessed at finished-equipment level. CT-1000-K26 has no intentional lead addition; leaded bronze variants rely on Annex III exemption 6(c) for copper alloys containing up to 4 % lead. | Annex III exemption 6(c) has been renewed with an expiry date of 30 June 2027 per Commission Delegated Directive (EU) 2025/2364. Verify the current exemption text before relying on it. |
| EU chemicals regulation (Regulation EC 1907/2006) | Metallic copper and tin are not on the SVHC candidate list. Lead is listed as SVHC. Articles containing an SVHC above 0.1 % w/w trigger Article 33 communication, and substance-information notification to the competent authority has applied since 5 January 2021. | No registration obligation for articles unless intentional release is intended. Confirm the current candidate-list count directly with the competent authority. |
| EU Conflict Minerals Regulation (EU) 2017/821 | Tin is one of the 3TG minerals. Obligations attach to EU importers of 3TG minerals and metals above the Annex I volume thresholds, not to downstream finished articles. | Applies from 1 January 2021. Due diligence includes management system, risk assessment, independent third-party audit and annual public reporting. Customers may still flow down CMRT reporting. |
| US Dodd-Frank Section 1502 / SEC Rule 13p-1 | Covers 3TG minerals and binds SEC-reporting issuers, who file Form SD. A component supplier is reached through customer flow-down rather than directly. | The rule remains in force following the 2014 Court of Appeals ruling on the compelled-speech element. Form SD filing practice continues. |
| California Proposition 65 | Lead and lead compounds are listed. Elemental copper and metallic tin were not identified as listed chemicals in this review. | Verify absence directly against the OEHHA list before making any statement about copper or tin. |
| EU End-of-Life Vehicles Directive 2000/53/EC | Annex II entry 3 covers copper alloys containing up to 4 % lead. Entries 4(a) and 4(b) concern bearing shells and bushes in engines, transmissions and air-conditioning compressors. | Relevant only when the bearing is installed in a vehicle. A new ELV Regulation proposal is pending; verify its status. |
| PFAS restriction (EU) | Not relevant to standard mineral-oil-impregnated bronze. It would become relevant to PTFE-modified or fluorinated-oil variants. | The broad-scope PFAS restriction under evaluation by the competent authority is a proposal, not law. RAC adopted its opinion in March 2026 and the SEAC opinion follows; a Commission draft is expected later. Do not state that PFAS are restricted. |
| UK chemicals regulation and UK restriction of hazardous substances | Separate regimes apply in Great Britain; Northern Ireland continues to follow the EU restriction of hazardous substances. | UK and EU exemption lists now diverge; check both for the target market. |
10.2 What a supplier inspection document does and does not do
| Type | Content |
|---|---|
| 2.1 | Declaration of compliance with the order, without test results. |
| 2.2 | Test report based on non-specific inspection, not necessarily the supplied lot. |
| 3.1 | Inspection certificate based on specific inspection of the supplied lot, validated by the manufacturer’s authorised inspection representative independent of production. |
| 3.2 | As 3.1, plus validation by the purchaser’s representative or an inspector designated by official regulations. |
All four documents are supplier quality records. None of them is a sector approval, and none of them is an airworthiness release certificate.
10.3 Sector approvals that a datasheet does not provide
| Sector | Applicable regime (examples) | What this document does not provide |
|---|---|---|
| Aerospace / airworthiness | The civil-aviation approval framework (type certificate, supplemental type certificate, parts-manufacturer approval, technical standard authorisations); release certificates issued under that framework; AS / EN 9100 quality management; special-process accreditation | No airworthiness release, no release certificate under that framework, no parts-manufacturer approval or technical standard authorisation, no special-process accreditation claim. A certificate of conformance is a commercial document, not an airworthiness release. |
| Defence | The defence-export control framework for defence articles; the dual-use export-control framework with a catch-all classification; specialty-metal flow-down clauses | No export-control classification determination. Classification is a self-assessment exercise that also depends on end use, end user and embargo rules; a formal governmental determination is the reliable route. Copper-base bronze is generally outside the statutory specialty-metal list, but flow-down clauses may still apply. |
| Automotive | Automotive quality-management specification; the production-part approval process with material-data reporting against GADSL | No production-part approval submission, no material-data record, no production part approval. Material-data reporting sits within the production-part approval process and is a prerequisite for signing the part submission warrant. |
| Food contact | EU Framework Regulation (EC) 1935/2004; Council of Europe Resolution CM/Res(2013)9 and the European technical guide for metals and alloys; national food-contact rules that differ by market; in the US, FDA food-contact provisions | No food-contact suitability conclusion. EU Regulation 10/2011 covers plastics and does not apply to metals, and there is no harmonised EU positive list for metals, so each market requires its own assessment. |
| Medical | EU MDR 2017/745; FDA 21 CFR 820 quality system regulation transitioning to the QMSR; ISO 13485; ISO 10993 biological evaluation; 510(k) or other marketing-authorisation pathways | No device approval, no biocompatibility conclusion. Biocompatibility evidence is material- and finish-specific and must be generated for the configuration as supplied. |
| Nuclear | ASME BPVC Section III certificates of authorisation and code symbol stamps (N, NA, NPT, NS, NV, N3) and QSC for material suppliers; 10 CFR 50.55a with 10 CFR 50 Appendix B and 10 CFR 21; RCC-M in France | No nuclear-grade conclusion. Nuclear supply requires a dedicated quality programme, source surveillance, material test reports and authorised inspector involvement. |
11. Frequently asked questions
What material is SAE 841 and which standard defines it?
SAE 841 is a legacy commercial designation for oil-impregnated sintered (powder metallurgy) bronze of nominal composition 90Cu–10Sn. The governing consensus specification is ASTM B438 / B438M, Bronze-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated), where the equivalent grade is Grade 1, Type 2, also written as MPIF Standard 35 code CT-1000-K26.
Is SAE 841 the same as SAE 660 or C93200 bearing bronze?
No. SAE 660 / UNS C93200 is a cast leaded tin bronze (about 83Cu-7Sn-7Pb-3Zn) supplied as dense material and normally externally lubricated. SAE 841 is a porous powder metallurgy bronze containing roughly 19 to 25 percent interconnected porosity filled with oil. Tensile strength, ductility and load capacity differ substantially, so the two are not interchangeable without redesign.
What are the PV limit and load limits for SAE 841 sintered bronze bearings?
Commonly published indicative values for oil-impregnated 90Cu–10Sn bronze are a PV limit of about 50,000 psi·ft/min (approximately 1.75 MPa·m/s), a static load limit of about 8,000 psi (55 MPa), a dynamic load limit of about 2,000 psi (14 MPa) and a sliding speed limit of about 1,200 ft/min (6.1 m/s). These are screening values that depend on shaft finish, housing rigidity, duty cycle and temperature.
What temperature can an oil-impregnated sintered bronze bushing reach?
The upper service temperature is set by the impregnating oil rather than by the bronze. With a standard mineral oil impregnation the usual continuous service band is roughly −10 to +100 ℃. Wide-temperature synthetic impregnation can extend the band to roughly −35 to +150 ℃. Oil oxidation, sweating and pore-blocking varnish are the limiting mechanisms at elevated temperature.
Can the bore be reamed or honed after installation?
It is generally discouraged. Reaming, honing or grinding smears metal across the surface and closes the interconnected pores that supply oil to the sliding interface. Where final bore accuracy is needed, follow the supplier’s sizing and re-impregnation sequence.
Does a material datasheet give airworthiness, food-contact, medical or nuclear approval?
No. A material property datasheet is reference data for engineering screening. Airworthiness release requires documentation such as the applicable airworthiness release certificate issued under the relevant approval. Food-contact, medical device, nuclear and defence supply each have their own conformity assessment routes, and none of them is satisfied by a datasheet.
12. Appendix: sources
Principal reference sources
- Disclaimer. This document provides material property reference data for general engineering screening and is published for information only. Values described as typical are indicative and are not specification minimums; values described as standard are requirements of the cited ASTM, MPIF, ISO, GB or JB documents as understood at the time of writing, and the current edition of each standard governs.
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
