Full definition
An unexpected and unscheduled stoppage of production equipment or an entire production line caused by equipment failure, process upset, safety incident, or external event (power outage, raw material shortage). Unplanned shutdowns are the most costly operational event in manufacturing and mining, with costs including: (1) Lost production — direct revenue loss during downtime (can be $10,000-1,000,000+/hour for large process plants). (2) Emergency repair — premium parts pricing, overtime labor, expedited shipping. (3) Collateral damage — a single component failure often damages adjacent components. (4) Quality losses — off-spec product during startup and shutdown transitions. (5) Safety risk — emergency conditions increase accident probability. (6) Customer impact — missed delivery commitments, penalties. Studies across industries show that unplanned downtime costs 5-10x more than equivalent planned maintenance. The primary goal of predictive and preventive maintenance programs is to convert unplanned shutdowns into planned shutdowns. Key metrics: number of unplanned stops per month, unplanned downtime hours, and unplanned-to-planned ratio (world-class <10% unplanned). Effective strategies: predictive maintenance technologies, critical spare parts inventory, documented emergency procedures, and cross-trained maintenance teams. Per ISO 55000 asset management framework.