| Babbitt Type |
Lead‑based (Pb–Sn–Sb family) or tin‑based (Sn–Cu–Sb family); selection depends on speed, temperature, and environmental restrictions. |
Material class / visual & metallography |
Choose tin‑based for higher temperature/speed applications; lead‑based for general low‑to‑moderate speed bearings where lead use is permitted. |
| Brinell Hardness (typical) |
Approx. 20–75 HB depending on alloy and casting/heat treatment (common service alloys often fall in lower half of this range). |
HB (Brinell) / portable hardness tester |
Measure hardness when assessing wear; re‑babbitting restores hardness profile to specification for the chosen alloy. |
| Radial Clearance |
Typical running clearance ranges: 0.025–0.15 mm (0.001–0.006 in) depending on journal diameter and operating conditions. |
mm / in (measurement with plastigage or bore gauge) |
Set final clearance after machining liner to size and with lubricant present; follow OEM/engineering guidance where available. |
| Shaft Surface Roughness |
Recommendation: Ra 0.2–0.8 µm for journal surfaces to promote stable hydrodynamic film and reduce embedment. |
µm Ra / profilometer |
Polish or grind shaft to target Ra before final assembly; remove high spots and sharp edges. |
| Operating Temperature |
Typical continuous service range: –20°C to ~120°C; occasional peaks up to ~150°C depending on alloy. |
°C / thermocouples or IR |
Monitor bearing temperature; persistent high temps indicate lubrication or load issues and warrant inspection/replacement. |
| Lubrication |
Common: mineral oil (filtered), EP oils, and synthetic base fluids (PAO) for extended life; grease acceptable for slow intermittent motion with appropriate formulation. |
Lubricant class / ISO VG |
Maintain clean oil supply, correct viscosity for temperature, and appropriate filtration; monitor for contamination and water ingress. |
| Common Failure Modes |
Fatigue spalling, metal transfer (seizure), embedding from foreign particles, corrosion, thermal softening, misalignment wear patterns. |
Observational / metallographic |
Use periodic inspections and oil analysis to detect early signs; address root cause (contamination, overload, lubrication) before replacement. |
| Inspection Frequency |
Routine visual/operational checks: each shift or start‑up; detailed inspection: monthly to quarterly; full teardown: annually or per service hours. |
Time / operating hours |
Adopt condition‑based intervals where vibration, temperature, or oil analysis indicate deviation from baseline. |
| Replacement Techniques |
Common methods: poured‑in‑place (in situ casting), preformed liners (machined), and spun or centrifugal casting for certain configurations. |
Process / machining |
Prepare housing (clean, true, and dry), apply proper bonding layer if required, pour or fit liner, finish‑machine to final clearance and polish. |
| Tools & Equipment |
Examples: bench lathe for liner machining, hygroscopic drying oven or heating equipment, hardness tester, profilometer, plastigage, clean assembly fixtures. |
Generic tools |
Use calibrated measuring tools; ensure work area cleanliness and temperature control for casting operations. |
| Safety & Environmental |
Handle molten metals and solvents with appropriate PPE; control lead exposure where applicable; dispose of waste per local regulations. |
PPE / compliance |
Use ventilation, respirators, and protective clothing during casting and machining; prefer lower‑hazard alloys when regulatory limits apply. |
| Expected Service Life |
Highly variable: from under 1 year in heavy shock/corrosive service to 10+ years in moderate, well‑lubricated conditions; typical moderate service 3–7 years. |
Years (service dependent) |
Use condition monitoring and trending (temperature, vibration, oil analysis) to predict replacement interval rather than calendar time alone. |
| Final Acceptance Criteria |
Bearing runs without abnormal vibration, temperature within expected range, correct running clearance, and no metallurgical defects or loose inclusions. |
Operational tests & inspection |
Perform run‑in checks, oil cleanliness verification, and a final dimensional inspection before returning to service. |