Useful Life
Useful life is the estimated operational period of an asset after early-life (infant mortality) failures are resolved and before wear-out failures begin, characterized by a constant, random failure rate where the asset generates economic value and serves its intended purpose.
In CMMS and asset reliability (e.g., ServiceGrid), useful life sets the planning horizon for replacement budgets, capital requests, and maintenance strategy (e.g., condition-based monitoring vs. run-to-failure), bridging maintenance decisions with accounting depreciation schedules.
Why is the failure rate constant during useful life?
Weak units fail early (infant mortality); the remaining population reaches equilibrium with lowest, predictable failure rate modeled by the exponential law.
How does useful life differ from physical durability?
An asset may physically run past useful life, but it is no longer cost-effective or reliable enough to justify service; useful life is economic, not just physical.
What metric validates reliability predictions during useful life?
MTBF (Mean Time Between Failures) is calculated using constant failure rate data; predictions are only valid within useful life, not during wear-out.
How is useful life determined in CMMS?
Via manufacturer specs, historical maintenance records, engineering assessments, industry standards, and accounting guidelines, factoring usage intensity and environment.