run-to-failure

**Run-to-failure** is the **maintenance policy of intentionally operating an asset until it fails, then repairing or replacing it** - it is appropriate only when failure impact is low and replacement is quick and inexpensive. **What Is Run-to-failure?** - **Definition**: Reactive strategy with no scheduled intervention before functional failure occurs. - **Suitable Assets**: Non-critical, low-cost components with minimal safety and production impact. - **Unsuitable Assets**: Bottleneck tools or components whose failure causes major downtime or contamination risk. - **Operational Requirement**: Fast replacement path and available spare parts when failure happens. **Why Run-to-failure Matters** - **Cost Advantage in Niche Cases**: Avoids preventive labor and part replacement for low-risk items. - **Planning Risk**: Unexpected failure timing can disrupt operations if criticality is misclassified. - **Safety Consideration**: Must never be used where failure creates personnel or environmental hazard. - **Throughput Exposure**: In fabs, misuse on important subsystems can cause significant output loss. - **Policy Clarity**: Explicit RTF designation prevents accidental neglect on high-impact assets. **How It Is Used in Practice** - **Criticality Screening**: Apply RTF only after formal failure consequence analysis. - **Spare Strategy**: Keep low-cost replacement inventory for fast corrective action. - **Periodic Recheck**: Re-evaluate policy if asset role or process dependency changes. Run-to-failure is **a selective economic strategy, not a default maintenance mode** - it works only when failure consequences are truly constrained and manageable.