We modified our custom analytics query for resource utilization KPIs last month, and now our OEE calculations are showing values that don’t match manual calculations. Some machines are showing OEE percentages above 100%, which is obviously incorrect.
The custom SQL view we’re using aggregates downtime codes and production counts:
SELECT ResourceID,
SUM(GoodCount) / SUM(PlannedCount) * 100 AS OEE
FROM ProductionData
GROUP BY ResourceID
We recently added logic to handle unplanned downtime differently, mapping certain downtime codes to exclude them from availability calculations. Since then, the OEE numbers have been inconsistent. The downtime code mapping seems correct in the configuration, but something in the calculation logic is off.
Has anyone dealt with custom OEE calculation issues in ft-12.0? I need to understand what’s wrong with our logic before the monthly management review.
Don’t forget about micro-stoppages. If your system isn’t capturing stops under 5 minutes, your availability will look artificially high. Make sure your data collection frequency is granular enough to catch these short events.
Also check if your custom view is handling overlapping downtime events correctly. If you have concurrent downtime codes recorded (like a breakdown during a material shortage), you might be double-counting downtime, which would skew your availability calculation. Use DISTINCT on your downtime duration aggregation.
Your formula is too simplified for proper OEE calculation. True OEE requires three components: Availability, Performance, and Quality. You’re only calculating Quality (good vs planned). You need to factor in actual runtime versus planned runtime, and actual cycle time versus ideal cycle time. The downtime code mapping affects availability, but your query doesn’t account for that properly.
Standard practice is to exclude planned downtime (scheduled maintenance, planned changeovers) from availability calculations, but include unplanned downtime (breakdowns, material shortages). However, changeover handling varies by industry - some count it as planned, others as unplanned depending on whether it was scheduled. You need to define your plant’s specific business rules for each code category.