Unplanned Maintenance refers to emergency equipment repairs triggered by unexpected failures, as opposed to scheduled preventive maintenance.

What Is Unplanned Maintenance?

• Trigger: Equipment breakdown, out-of-spec production, safety event
• Impact: Production stop, queue buildup, missed delivery
• Cost: 3-10× higher than equivalent planned maintenance
• Metrics: MTTR (Mean Time To Repair), unplanned downtime %

Why Reducing Unplanned Maintenance Matters

Every hour of unplanned downtime in a semiconductor fab costs $50K-200K in lost production. Prevention through predictive maintenance pays massive dividends.

<svg viewBox="0 0 527 264" xmlns="http://www.w3.org/2000/svg" style="max-width:100%;height:auto" role="img"><rect x="0" y="0" width="527" height="264" rx="12" fill="#0d1117"/><g font-family="ui-monospace,SFMono-Regular,Menlo,Consolas,&quot;Liberation Mono&quot;,monospace" font-size="14"><text xml:space="preserve" x="20" y="31.7"><tspan fill="#c9d1d9">Maintenance Strategy Comparison:</tspan></text><text xml:space="preserve" x="20" y="50.7"><tspan fill="#c9d1d9">Reactive:     Run to failure </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> Emergency repair </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> Resume</tspan></text><text xml:space="preserve" x="20" y="69.7"><tspan fill="#c9d1d9">              ████████████╳</tspan><tspan fill="#6e7681">───────────────────</tspan><tspan fill="#c9d1d9">██████████</tspan></text><text xml:space="preserve" x="20" y="88.7"><tspan fill="#c9d1d9">                          </tspan><tspan fill="#6e7681">↑</tspan><tspan fill="#c9d1d9"> Long unplanned downtime</tspan></text><text xml:space="preserve" x="20" y="107.7"></text><text xml:space="preserve" x="20" y="126.7"><tspan fill="#c9d1d9">Preventive:   Scheduled PM </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> Brief planned stop </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> Resume  </tspan></text><text xml:space="preserve" x="20" y="145.7"><tspan fill="#c9d1d9">              ████████████</tspan><tspan fill="#6e7681">│─│</tspan><tspan fill="#c9d1d9">████████████████████████████</tspan></text><text xml:space="preserve" x="20" y="164.7"><tspan fill="#c9d1d9">                          </tspan><tspan fill="#6e7681">↑</tspan><tspan fill="#c9d1d9"> Short planned maintenance</tspan></text><text xml:space="preserve" x="20" y="183.7"></text><text xml:space="preserve" x="20" y="202.7"><tspan fill="#c9d1d9">Predictive:   Monitor </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> Predict </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> Plan optimal timing</tspan></text><text xml:space="preserve" x="20" y="221.7"><tspan fill="#c9d1d9">              ████████████████</tspan><tspan fill="#6e7681">│─│</tspan><tspan fill="#c9d1d9">███████████████████████</tspan></text><text xml:space="preserve" x="20" y="240.7"><tspan fill="#c9d1d9">                              </tspan><tspan fill="#6e7681">↑</tspan><tspan fill="#c9d1d9"> Minimal disruption</tspan></text></g></svg>

Unplanned Maintenance Reduction:

• Implement predictive maintenance (sensor monitoring)
• Stock critical spare parts
• Cross-train maintenance technicians
• Root cause analysis to prevent recurrence