Babbitt is the classic journal-bearing surface — a tin-base white metal (88% Sn, 7% Sb, 4% Cu, matching ASTM B23 Grade 2 and Oerlikon Metco Sprababbitt A / TAFA 04T chemistry) at only ~24 HB. In a hydrodynamic bearing it isn't supposed to touch the shaft — a wedge of pressurized oil carries the load. When contact happens, babbitt does three things nothing else matches: embeds hard particles instead of scoring the journal, cold-flows to match shaft geometry, and smears before it galls. The shaft survives; the babbitt gets rebuilt.

That's where thermal spray comes in. Arc-wire and flame-wire babbitt (Sprababbitt A, TAFA 04T, PMET 542) lay down dense, low-oxide coatings at 10-60 mils for routine rebuilds and up to 0.200"+ for heavier work, then machine back to OEM print. Standard practice pre-wets the steel shell with a tin-flux bond layer so the babbitt fuses rather than sitting on. The win over cast rebabbitting: lower heat input, no distortion, and field repair on turbine lower halves and hydro thrust rings too large to ship. Service caps at 130°C continuous (Kingsbury's threshold); above that, tin creep kills fatigue life. HTS sprays babbitt on steam- and gas-turbine journal bearings, Kingsbury-style thrust shoes, large motor sleeves, and pump/compressor bearings. Send the OEM print and shaft dimensions — we'll confirm process, thickness, and bond-layer approach.

Technical data

Hardness: ~20-40 HV as-sprayed (ASTM B23 Grade 2 wrought datum ~24 HB at room temp; thermal-spray deposits fall within the same band and softens to ~12 HB at 150°F per Belmont Metals)
Hardness (HRC): Not applicable — Babbitt is a white metal soft enough to be tested on Rockwell B or Brinell only; HRC scale doesn't reach this range
Bond strength: ~1,200 psi mechanical bond when sprayed direct to grit-blasted steel (A&A Thermal Spray datum); higher metallurgical-grade bonds achieved via tin-flux bond layer — the standard practice where the bearing shell is first 'tinned' with a Tin-Flux compound or #2 babbitt pre-wash so the sprayed babbitt wets and fuses rather than sitting on as a mechanical layer
Max service temp: ~300°F absolute limit — industry practice caps continuous service at 265°F (Kingsbury), with babbitt entering plastic-creep at ~320°F (160°C) and tin transitioning to liquid phase above 450°F
Max service temp: ~130°C continuous operating limit (Kingsbury industry-standard threshold); 150°C short-term maximum before creep dominates
As-sprayed porosity: Arc-sprayed Sprababbitt A / TAFA 04T: 1-3% when process is dialed in — 'dense, well-bonded, low in oxides, bright metallic appearance' per Oerlikon spec. Flame-sprayed deposits run 3-8% and are oxide-richer. Post-spray machining to <50 RMS finish on the bearing ID is standard
Typical thickness: Spray build-up 10-60 mils for worn-bearing restoration to OEM OD; heavier rebuilds and cast-replacement work 60-250 mils (>0.200" per A&A datasheet). Machined back to original drawing dimension after spray
Melting range: ~464°F solidus (tin side of eutectic); ~695°F liquidus for the 88/7/4 alloy per A&A Thermal Spray datasheet — exceptionally low for a bearing material and the reason flame- and arc-spray work so well
Density: 7.4 (ASTM B23 Grade 2 wrought reference, 0.2667 lb/in³); as-sprayed deposits measure ~7.3-7.4 when dense, though thin arc-sprayed layers can drop toward 3 g/cc equivalent coating weight due to oxide content and porosity

Where it earns its keep

Extremely low friction against hardened steel shafts — the original purpose and still unmatched by polymer alternatives at heavy loads
Embeddability — soft matrix swallows hard particles so the shaft journal survives contamination
Conformability — babbitt deforms to absorb shaft misalignment and geometry errors
Lead-free Sn/Sb/Cu chemistry meets current OEM and RoHS-style environmental specs — Oerlikon Metco Sprababbitt A, TAFA 04T, PMET 542, and equivalents all ship lead-free
Thermal spray enables field repair of very large bearings (turbine lower halves, hydro thrust rings) that cannot be shipped for cast rebabbitting
Lower heat input than cast rebabbitting — substrate stays cold, no warping, no distortion of precision bores
Fast cycle time vs. cast + machine — arc-sprayed babbitt lays down at 10-20 lb/hour with minimal fixture cost
Machines easily with conventional HSS and carbide tooling to sub-50 RMS finish

Where it doesn't

Maximum continuous service 130°C (265°F) — not a high-temperature material. Above 150°C the tin matrix creeps and load-carrying capacity collapses
Bond is mechanical when sprayed direct to grit-blasted steel (~1,200 psi); the gold-standard approach uses a tin-flux bond layer or 'tinning' pre-wash to achieve metallurgical fusion. Do not skip this step on heavy-duty bearings
Thermal-spray babbitt is lower in fatigue strength than cast babbitt — OEMs typically specify cast rebabbitting for new build and spray for field repair / worn-bearing reclamation. Confirm the repair spec before quoting
Fatigue life depends on thickness: thicker babbitt fatigues faster, so keep sprayed layers no thicker than the drawing calls for
Oxide content in arc-sprayed deposits must be controlled — dirty atomization air, worn nozzles, or cold arc start all drive oxide stringers that act as fatigue-crack initiators
Shaft hardness still matters — babbitt protects the journal only when the shaft is harder; soft or galled shafts must be ground or replaced before rebabbitting
Porosity in as-sprayed deposits holds oil (a modest benefit) but also traps contaminants — specify post-spray burnishing or impregnation on critical applications
Not a hardfacing — wrong tool for abrasion, galling, or erosion duty. Babbitt is a bearing surface, full stop

Which process, when?

Electric arc spray is the dominant production process for thermal-sprayed babbitt — Sprababbitt A, TAFA 04T, and PMET 542 are all arc-wire products. Two 1.6-2.0 mm babbitt wires are melted in a 350-amp arc and atomized onto the prepped bearing shell at high deposition rate, producing dense, low-oxide coatings with the bright metallic appearance that OEMs expect. Combustion (flame) wire spray is the traditional alternative, still used for smaller shops and field work where air and propane are easier to source than a 3-phase arc rig; flame deposits run a bit more porous and oxide-rich but finish identically after machining. Cast rebabbitting remains the OEM-preferred process for new bearings and heavy-duty rebuilds — the shell is preheated, tinned, and the babbitt is poured molten into a centrifugal or static mold, yielding maximum fatigue life. Thermal spray wins on speed, low heat input, and field repairability; casting wins on fatigue strength and thick-section integrity. HTS applies babbitt by arc wire spray and flame wire spray, with proper tin-flux bond-layer prep. For worn journal bearings, bearing-shell rebuilds, or field repair on equipment too large to ship, send dimensions and the OEM print — we'll spec the process and the bond-layer approach.

Sources

Data points on this page draw on the following published references. Nothing here replaces a material-specific review by our process engineers — but it's the working starting point.

A&A Thermal Spray Coatings — Using Babbitt As A Metalizing Material
“A lead free, high grade tin based Babbitt wire has been created primarily for combustion and electric arc wire spraying. Typical wire composition 3.5% copper, 7.5% antimony, tin balance. Bond strength 1,200 PSI; melting point ~695°F; density 3 g/cc; as-sprayed surface finish 400-600 aa; machined finish <50 aa; maximum thickness >0.200"; coating weight 0.03 lb/ft²/.001". The coating prevents bearing wear by discouraging welding together of moving parts; lines bearing shells made from bronze, steel, and cast iron.”
Oerlikon Metco — Sprababbitt A Thermal Spray Wire (myMetco)
“Sprababbitt A is a special high grade, tin-based babbitt wire that is manufactured exclusive for thermal spray. Coatings of Sprababbitt A are particularly suitable for high speed and heavy duty bearing surfaces that required coatings of the highest possible quality, especially for critical applications. The coatings are ductile, low in oxides and exhibit a bright, metallic appearance. Designed for application using electric arc wire spray or combustion wire spray.”
Polymet PMET 542 Babbitt Wire (TAFA 04T / Sulzer Metco Sprababbitt equivalent)
“PMET 542 is a high tin, lead free Babbitt wire specifically designed for spraying in arc spray and flame spray systems. Produces dense, well-bonded coatings particularly applicable to high speed and heavy duty bearings. Equivalent to TAFA 04T and Sulzer Metco Sprababbitt.”
Kingsbury — Babbitt Bearing Repair Services
“Kingsbury is the industry leader in rebabbitting of turbine bearings, babbitt bearing repair, and rebabbitting services. Babbitt on hydrodynamic bearings is a layer of sacrificial material covering the working face of the bearing, designed to be soft enough that contaminants can embed in it, typically composed of an alloy of tin. Services include thrust bearings (including mechanical scraping of bearing shoes) and large journal bearings.”
Kingsbury — How to Estimate Babbitt Temperature
“265°F (130°C) is identified as the threshold for acceptable babbitt temperature operation. Temperature analysis becomes important when bearing load exceeds 400 PSI, collar surface speed exceeds 15,000 feet per minute, or inlet oil temperature surpasses 120°F. Performance curves based on light turbine oil [150 SSU @ 100°F] supplied at 115°F.”
Fusion Babbitting Co. — Arc Flame Spray Babbitt Bearing Restoration
“The Arc Flame Spray process employs two electrically conductive wires (from 1.6mm to 2mm in diameter) that are melted by means of an electric arc process operating up to 350 amps. The molten material is propelled onto the bearing surface using compressed air atomization. Cold process methodology where molten particles impacting and adhering to the target surface rapidly solidify to form a very strong and dense coating. The base material remains at low temperatures, preventing warping or metallurgical damage. Specializes in restoring bearings for turbines, generators, pumps, and motors.”
Belmont Metals — Differences Between Different Grades of ASTM B23 Babbitt
“ASTM-B23 #2 contains roughly 88% up to 90% tin with 7%-8% antimony and 3% to 4% copper. All tin-based grades share consistent amounts of trace iron, bismuth, zinc, aluminum, cadmium, and arsenic. Material demonstrates strong corrosion resistance and easy bonding. Grade 2 is softer than Grade 1 yet maintains capability for demanding load scenarios; commonly employed in heavy machinery, compressors, and electric motors.”
Kapp Alloy — ASTM B23 Grade 2 Tin Babbitt (DuraKapp #2)
“ASTM B23 Grade 2 composition 89% tin, 7.5% antimony, 3.5% copper. Brinell hardness 24.5/12 (room temp / elevated). Tensile strength 9,200 psi; elongation 8.0%; compressive strength 6.44 tons/in²; density 0.2667 lb/in³. Ideal journal bearing material commonly used for sleeve-bearing applications in motors, engines, turbines, compressors, pumps, marine and steam engines, and electrical machinery.”
Machinery Lubrication — Babbitt: The Other Bearing Lubrication
“The surface is typically 'tinned' using either #2 Babbitt or a premixed Tin-Flux compound, with the main purpose being to ensure a uniform bond between the Babbitt and the Steel bearing shell. A simple failure in the bond between the base metal and the Babbitt material can be a root cause of bearing failure. Although tin enters the liquid phase near 450°F, the liquid phase for the Babbitt alloy microstructure does not occur until temperatures exceed 600°F. The Babbitt starts becoming plastic or creep at 320°F (160°C).”
AIM Alloys — Babbitt Bearing Alloys Reference PDF
“Tin-base babbitt alloys (ASTM B23 Grades 1, 2, 3) contain 83-91% tin with antimony and copper hardeners; lead-free white-metal bearing materials with excellent embeddability, conformability, and corrosion resistance. Used in journal and thrust bearings for heavy-duty rotating equipment.”

Material data on this page is provided as a general reference and can vary by lot, substrate, and application. Contact HTS to confirm the right material and specification for your specific part.

Babbitt

Technical data

Where it earns its keep

Where it doesn't

Typical applications

Wear modes addressed

Industries

Substrates

Which process, when?

Sources

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