Bathtub Curve (Failure Rate Pattern)

Definition

Bathtub Curve is a graph that illustrates how the failure rate of products or equipment changes throughout their lifecycle. Resembling the shape of a bathtub with high failure rates at both the beginning and end while remaining low in the middle, it serves as a fundamental concept in reliability engineering for equipment lifecycle management.

Applications in Manufacturing

Three Failure Phases

• Early Failure Period: High failure rate immediately after equipment installation due to initial defects, installation errors, and component quality issues
• Useful Life Period: Stable operation phase where failure rate remains low and constant
• Wear-out Failure Period: Late-stage phase where failure rate increases rapidly due to component aging and wear

Predictive Maintenance Strategy Development

Manufacturing sites establish phase-specific maintenance strategies based on the bathtub curve. Intensive inspections and burn-in tests are conducted initially, preventive maintenance is minimized during the useful life period, and components are replaced before entering the wear-out phase.

Manufacturing AI Applications

AI-based failure prediction systems analyze sensor data to determine in real-time which phase of the bathtub curve equipment is in. Machine learning models predict when equipment will enter the wear-out failure period, suggesting optimal component replacement timing to prevent unexpected downtime and minimize maintenance costs. When combined with digital twin technology, equipment lifespan can be simulated in virtual environments to derive optimal operating conditions.