Investigating production stoppages with machine and maintenance records

Understanding a stoppage requires more than its start and finish times. To assess its effect on production, reconstruct what the equipment was doing before it stopped, what work was carried out and the conditions under which it returned to operation.

Work orders and operating records answer different questions

A computerised maintenance management system (CMMS) records requests, assigns responsibility and documents work, spare parts and completion dates. Machine, sensor and operator records describe equipment behaviour during production, waiting and stoppages. Linking both sources by asset and timestamp helps interpret an intervention while keeping observed changes distinct from confirmed causes.

Five useful records for investigating a stoppage

• Asset identification and the product being manufactured.
• The last cycles, states and events recorded before the stoppage.
• Time of detection, start of maintenance work and return to operation.
• The work performed and the cause documented by maintenance, distinguished from the initial suspected cause.
• Behaviour after restart and any recurrence of the problem.

Classify stoppages by their cause

A machine may stop because of a material shortage, a logistics delay, a product change, planned work or a functional failure. A defined event taxonomy is essential for combining these records into comparable availability and reliability indicators.

What to define before calculating MTBF or MTTR

Define which events count as failures, the observation period and what “operational equipment” means. MTBF requires a consistent basis for operating time and the number of failures under the agreed criteria. MTTR requires the corresponding repair times under those same criteria. Different definitions can produce different values for the same equipment even when the underlying records are consistent.

Use data to verify an intervention

After an intervention, compare equivalent conditions and check whether the behaviour is sustained. An improvement may appear as fewer stoppages, shorter downtime or a more stable cycle. Confirming it requires sufficient records over a defined period, beyond the impression from the following shift.

To apply this approach in your plant, see maintenance and production.

The guide Actual operating hours and failures explains the MTBF and MTTR criteria in more detail; KERN IoP | MONITOR shows how to review historical records when those signals are integrated.