How to Accurately Measure Reliability in Manufacturing

In industrial operations, reliability is the direct outcome of maintenance. Accurately measuring it is essential, as maintenance investments can be substantial and their value must be clear.

Reliable data informs decision‑making, drives continuous improvement, and keeps collection effort minimal. The most effective approach is to log losses at the equipment‑location level—where each machine is uniquely identified.

Losses represent units that could have been produced or sold but weren’t, due to factors such as inventory gaps, material quality, equipment failure, or operator skill gaps.

Follow this streamlined process to capture losses:

• Define the maximum production rate for each major manufacturing unit and product grade.
• Set a realistic target—typically 90 % of maximum capacity—for each shift.
• Record any shortfall below this target using a simple, consistent system.
• Assign a reliability or process engineer to review daily loss data, ensuring it is actionable.
• Analyze trends regularly and prioritize high‑impact improvement initiatives.

Operators should log losses immediately. While paper forms work, an electronic log—whether built into your maintenance system or a custom database—prevents data duplication and speeds analysis.

Required data for each loss event:

• Manufacturing unit name
• Date and start time
• Date and end time
• Units lost
• Known cause
• Equipment number and description (if applicable)
• Additional remarks for future analysis

Daily reviews confirm causes, assign responsibility, and designate the department best positioned to prevent recurrence—rather than merely assigning blame.

After two years of disciplined loss recording, analysis revealed that 87 of 12,000 equipment items accounted for 80 % of unscheduled downtime. Targeted preventive maintenance on these items dramatically reduced losses, as shown below.

Other tools, such as automated OEE instrumentation, can complement this approach when warranted.

Reliability remains the most critical KPI for maintenance. Report it regularly, filter by department and discipline, and use the insights to drive continuous improvement.