Babbitt & white metal bearings: composition, oil and temperature
Babbitt is a family of bearing alloys, commonly tin-based or lead-based, used as the working lining in a plain bearing. It is not a ball-bearing series or one universal composition. Identify the alloy, backing, bearing geometry and lubrication system separately before interpreting a material name, clearance or temperature value.
On this page16 sections ⌄
What is a babbitt bearing? Separate the lining from the structure
A soft babbitt working layer is commonly bonded to a stronger backing. Waukesha describes steel and copper-chrome (CuCr) backings, with different heat-conduction behaviour. Do not mistake the thin working layer for the whole load-supporting structure.
Conformability means accommodating small geometric deviations; embedability means accepting small particles into the softer surface. Neither property makes contaminated oil acceptable. Preserve the distinction between the alloy's behaviour and the complete bearing's design.
On smaller screens, scroll the table sideways to read all columns.
| Term | What it describes | What it does not identify |
|---|---|---|
| Babbitt / whitemetal | A bearing-alloy family; the exact formulation must be named. | A universal grade, lubricant or size. |
| Babbitt-lined bearing | A working alloy layer supported by a backing. | The backing composition or bond quality from appearance alone. |
| Journal / sleeve bearing | A plain-bearing arrangement supporting a rotating journal and radial loading. | A particular alloy: sleeve describes geometry, not chemistry. |
| Thrust bearing / thrust pad | A surface arrangement supporting axial loading through the lubricant film. | The same geometry or clearance as a journal sleeve. |
| Fixed profile / tilting pad | Two ways to provide the working surface geometry. | Interchangeability just because the shaft or housing diameter matches. |
| Split bearing | A construction divided for assembly or service. | A separate babbitt alloy grade or an automatic repair method. |
Babbitt composition: named nominal alloy examples
These are Belmont Metals' stated nominal formulations, not a reproduction of the full ASTM standard or a batch certificate. Percentages stay attached to the named product. Sn = tin, Sb = antimony, Cu = copper, Pb = lead and As = arsenic.
Not listed does not mean certified zero or absence of trace impurities. Balance is retained as published rather than replaced with a guessed assay. A supplier's #4 product name must not be silently converted into ASTM Grade 4. Verify the exact specification and certificate when identifying an unknown or legacy lining.
On smaller screens, scroll the table sideways to read all columns.
| Manufacturer grade label / product code | Sn % | Sb % | Cu % | Pb % | As % |
|---|---|---|---|---|---|
| ASTM B-23 Grade 1 / 7915 | 91 | 4.5 | 4.5 | Not listed | Not listed |
| ASTM B-23 Grade 2 / 7881 | 89 | 7.5 | 3.5 | Not listed | Not listed |
| ASTM B-23 Grade 3 / 7852 | 84 | 8 | 8 | Not listed | Not listed |
| ASTM B-23 Grade 11 / 78821 | 87.5 | 6.75 | 5.75 | Not listed | Not listed |
| ASTM B-23 Grade 13 / 58412 | 6 | 10 | Not listed | Balance | Not listed |
| ASTM B-23 Grade 8 / 5807 | 5 | 15 | Not listed | 79.55 | 0.45 |
| ASTM B-23 Grade 15 / 5808 | 1 | 16 | Not listed | Balance | Not listed |
| ASTM B-23 Grade 7 / 5752 | 10 | 15 | Not listed | Balance | 0.45 |
| #4 Babbitt Alloy / 5906 | Not listed | 10 | Not listed | 90 | Not listed |
White-metal melting point: solidus, liquidus and pouring temperature
An alloy can melt over a range. Solidus marks the start of melting; liquidus marks the fully liquid boundary. A published pouring temperature is a separate process value. None of the three is a safe running temperature for an assembled bearing.
The two unit columns retain the manufacturer's rounded values. The Grade 2 pouring value and Grade 13 temperatures are withheld because their published Celsius/Fahrenheit pairs conflict; no preferred value has been guessed. Grades with no temperature data are not filled by copying a neighbouring grade.
The table is a material record, not a casting procedure. Actual work also depends on alloy identity, shell preparation, bonding, equipment, moisture control, ventilation and inspection. Do not use a melting point or this table alone to pour, repair or commission a bearing.
On smaller screens, scroll the table sideways to read all columns.
| Belmont product grade | Solidus °C / °F | Liquidus °C / °F | Published pouring value °C / °F |
|---|---|---|---|
| Grade 1 | 223 / 433 | 371 / 700 | 441 / 825 |
| Grade 2 | 241 / 466 | 354 / 669 | Withheld: unit-pair conflict |
| Grade 3 | 240 / 464 | 422 / 792 | 490 / 915 |
| Grade 8 | 237 / 459 | 272 / 522 | 340 / 645 |
| Grade 15 | 248 / 479 | 281 / 538 | 350 / 662 |
| Grade 7 | 240 / 464 | 268 / 514 | 338 / 640 |
Real bearing-family examples: journal, sleeve and thrust
These examples distinguish an alloy maker from a finished-bearing designer. They are not a ranking or a complete supplier directory. For a particular machine, start with its drawing and bearing record rather than replacing the original design with the nearest named material.
On smaller screens, scroll the table sideways to read all columns.
| Manufacturer reference | Documented construction | Scope boundary |
|---|---|---|
| Kingsbury fixed-profile KN family | Babbitt-lined, steel-backed journal bearings; the manufacturer identifies ASTM B23 Grade 2 as the usual standard lining. | A family example, not a part-number match for an engine or legacy machine. |
| Waukesha babbitt journal designs | Sleeve and tilting-pad configurations. | Geometry and operating conditions remain application-specific. |
| Waukesha babbitt thrust designs | Fixed-profile and tilting-pad options, including equalizing and non-equalizing arrangements. | A thrust-pad material name does not identify a journal-bearing replacement. |
| Belmont babbitt alloys | Named alloy products with published nominal chemistry. | Alloy supply is not the same as a finished bearing, fitment approval or repair service from BearingScope. |
What oil lubricates a babbitt bearing? A scoped manufacturer example
Babbitt does not prescribe one oil grade. In a hydrodynamic design, the working oil film depends on geometry, speed, load, clearance and oil viscosity. The oil supply also removes heat; an alloy name does not establish the necessary flow.
This example uses the current Kingsbury fixed-profile product page reviewed on 2 October 2026, not an undated blend of catalogue editions. It is not permission to add an EP oil, grease or another fluid to an existing machine. Keep the approved lubricant and commissioning instructions attached to the exact bearing and equipment.
On smaller screens, scroll the table sideways to read all columns.
| Kingsbury fixed-profile family guidance | Recorded value or requirement | Do not generalize to |
|---|---|---|
| Oil grades named for most applications | ISO VG 32, 46 or 68, without EP additives | Every babbitt-lined machine or every lubricant formulation. |
| Supply temperature on the current product page | 45–55°C | Bearing-metal temperature or a universal oil-temperature target. |
| Filtration wording | 25 microns or better | A complete filter specification: efficiency rating and system requirements still matter. |
| Supply and cooling | Continuous high-quality oil supply; flow depends on operating conditions | A fixed flow rate derived only from bore diameter. |
Why there is no universal babbitt-bearing clearance chart
Oil clearance is a design parameter, not an alloy-composition property. Bearing diameter, length, bore profile, load, speed, temperature, oil and stability requirements affect the design. A single clearance-per-inch rule cannot certify all sleeve, split or tilting-pad bearings.
For a simple circular, concentric geometric definition, diametral clearance is twice radial clearance. That relationship does not supply a design value or describe all loaded, profiled or tilting-pad geometries. A model-specific clearance chart is still required where the machine's documentation calls for one; this page does not invent it.
On smaller screens, scroll the table sideways to read all columns.
| Record | What the value must specify |
|---|---|
| Clearance definition | Radial versus diametral, assembled versus free-state, and measurement temperature. |
| Component geometry | Actual journal and assembled bearing measurements at the specified locations. |
| Operating conditions | Load direction and magnitude, speed range, oil grade and supply conditions. |
| Design acceptance | The drawing's limits, measurement method, tolerances and revision. |
| Repair evidence | Material identity, lining thickness and bond/geometry inspection records as required by the design. |
Running temperature and melting point answer different questions
Babbitt can lose useful strength well below its melting range. Waukesha describes 130°C (266°F) as typical industry maximum-temperature practice for babbitt bearings, not a universal permission for every design to run at that temperature.
Monitor the quantity the equipment specifies: oil-inlet, drain-oil and local bearing-metal temperatures are not interchangeable. Use the design's normal, alarm and trip limits and sensor position. A trend toward an abnormal temperature matters even when the alloy remains far below its solidus.
Kingsbury identifies oil-supply or viscosity problems, interrupted film, inadequate clearance, load and speed among overheating considerations. Discoloration, wiping, cracking or deformation are evidence to investigate, not a reliable remaining-life estimate. Do not continue running a damaged bearing on the basis of a material melting-point table.
Rebabbitting, remetalling, machining and scraping: different stages
Rebabbitting renews the bearing lining; it does not automatically correct the cause of failure. Kingsbury's published repair scope includes material verification, removal and recasting, restoration of geometry, bond inspection and dimensional checks. The sequence and acceptance limits must come from the actual repair specification.
Scraping is not a generic way to repair a wiped lining or increase clearance until a shaft turns. This page does not provide scraper angles, spot-count criteria, a pour recipe or machining allowances for an unidentified bearing. Molten-metal and lead-alloy work require qualified procedures and safety controls; BearingScope does not offer a repair service.
On smaller screens, scroll the table sideways to read all columns.
| Stage | Question the repair record must answer |
|---|---|
| Condition assessment | Was the damage caused by lubrication, contamination, alignment, load, temperature or another system issue? |
| Alloy and backing identity | Which material and backing are specified, and how was the existing component identified? |
| Lining renewal | Which approved process, bonding preparation and inspection plan apply to this component? |
| Machining / scraping | Which drawing geometry and clearance must be restored, and how will they be measured? |
| Bond / surface inspection | Which documented inspection method and acceptance criteria demonstrate a suitable bond and condition? |
| Return to service | Are the dimensional records, lubrication problem and commissioning requirements resolved? |
Can bronze replace a babbitt bearing? Not from dimensions alone
Bronze and babbitt are different material choices, not interchangeable names for the same lining. Waukesha's fluid-film design guidance treats material, geometry, lubrication and operating duty as linked design decisions. A matching bore and outside diameter do not validate a substitution.
The same limitation applies to a change to aluminium-tin, polymer or another lining. A manufacturer's engineered replacement option is not blanket approval for a generic solid-bronze bush, automotive shell or legacy engine bearing. Exact substitution evidence remains a separate requirement.
On smaller screens, scroll the table sideways to read all columns.
| Before a material change | Evidence needed |
|---|---|
| Working surface and backing | The proposed alloy, construction, bond and counterface requirements. |
| Oil film and thermal behaviour | A bearing-design evaluation using actual load, speed, clearance, oil and temperatures. |
| Contamination and alignment | The permitted environment and the equipment's control of those conditions. |
| Fit, retention and geometry | The complete drawing, not only d×D×B. |
| Verification | Documented acceptance, monitoring and commissioning requirements for the changed design. |
What the evidence can — and cannot — tell you
| Observation or context | Interpretation to consider | Verification needed |
|---|---|---|
| A white-metal or babbitt description | Identifies a material family, not a complete bearing | Obtain the alloy designation, backing material and component drawing. |
| A melting or pouring temperature | An alloy/process property, not an operating limit | Keep the alloy grade, units and temperature definition with the value. |
| A proposed repair or bronze replacement | Changes more than the outside dimensions | Verify geometry, oil film, material compatibility and acceptance requirements. |
A practical investigation sequence
Identify and record
Record the machine, bearing position, drawing revision, shaft size, load, speed and lubricant system. Distinguish a journal bearing from a thrust pad or combination assembly.
Check the context
Obtain the alloy and backing specifications, actual measurements, oil analysis and temperature history. Preserve damage photographs and material evidence before cleaning or machining.
Verify before acting
Compare the evidence with the exact equipment and bearing requirements. Use qualified material and bearing specialists for repair, bond inspection or design changes; a generic composition table is not an acceptance specification.
Keep the decision traceable
Keep the dimensional, material, inspection and operating records together. Follow the equipment's controlled commissioning procedure after an approved repair or replacement.
Capture the information a model search cannot guess
Keep this checklist with your inspection or comparison. Checking a box only records that you have collected the item; it does not certify the bearing.
0 of 4 information groups recorded.
Technical basis & editorial scope
Original BearingScope workflow, written for catalogue research and comparison. Manufacturer material is used to check principles, not copied as a product endorsement or substituted for model-specific instructions. Reviewed 1 October 2026.
- Belmont Metals — Babbitt alloy records — Nominal compositions and named temperature fields. Conflicting unit pairs withheld. Reviewed 2 October 2026.
- Waukesha Bearings — Babbitt construction — Lining/backing, journal/thrust forms and the stated temperature-practice context. Reviewed 2 October 2026.
- Waukesha Bearings — Fluid-film bearing design — Material, geometry, lubrication and operating-duty relationship; not a substitution approval. Reviewed 2 October 2026.
- Kingsbury — Fixed-profile journal family — Scoped KN-family lining and current oil-supply guidance, not a universal machine prescription. Reviewed 2 October 2026.
- Kingsbury — Rebabbitting scope — Repair stages and inspection scope, not a DIY casting or scraping procedure. Reviewed 2 October 2026.
- Kingsbury — Overheating investigation — Symptoms, oil-film considerations and local metal-temperature measurement. Reviewed 2 October 2026.
Source addresses and collection status are retained in the internal audit. No unpublished dimensions, torque settings, service intervals or interchange approvals are inferred.