P-F Curve
The P-F curve describes how a failure develops from the point a potential failure becomes detectable (P) to the point of functional failure (F). The P-F interval is the warning time in between — the window in which condition monitoring can catch the fault and act.
The P-F curve is a core idea in predictive maintenance. Different detection techniques 'see' a developing fault at different points: ultrasound and oil analysis often detect a bearing problem earliest, then vibration, then heat, then audible noise just before failure. A longer P-F interval means more time to plan a repair. Choosing techniques that detect early — and monitoring at the right frequency — is what makes condition-based maintenance work.
Related terms
Predictive Maintenance (PdM) · Condition Monitoring · Vibration Analysis · Remaining Useful Life (RUL)
Related guides
Software
Where this applies
Transitioning to condition-based maintenance · Setting up a dynamic balancing programme · Condition-Based vs Time-Based Maintenance · State of Predictive Maintenance 2026 · The predictive-maintenance market trajectory