How would you store data for correct OEE calculation?

To accurately calculate OEE (Overall Equipment Effectiveness), data reflecting three key components must be stored: availability, performance, and quality.

1. Availability: the time when equipment was actually available for operation. This requires storing data on scheduled operating time and actual downtimes (stoppages, maintenance, failures).

2. Performance: the actual operating speed of the equipment compared to the nominal speed. Data needed include the number of units produced over a certain period and the nominal speed.

3. Quality: the number of good units relative to the total produced. Data on defective and good products should be stored.

Example storage structure:

• Table/entity "Production Shifts" with date, start and end times.
• Table "Downtime Events" with downtime type, start and end times.
• Table "Production Data" with the number of units produced, number of defective units, and operating time.

This approach allows aggregating data for OEE calculation using the formula:

OEE = Availability × Performance × Quality

where
Availability = (Operating time - Downtime) / Operating time
Performance = Actual units / (Nominal speed × Operating time)
Quality = Number of good units / Total units produced