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OEE Losses, Utilization and Targets: What to Measure
OEE describes effectiveness during planned production. Schedule utilization describes how much of a larger time window is planned for production. Keep those denominators separate before setting a target.
Use loss categories that reconcile
| Factor | Typical category | Recording rule |
|---|---|---|
| Availability | Breakdowns; setup and adjustment | Record non-overlapping stopped minutes within planned time. |
| Performance | Small stops; reduced speed | Use a declared stop-duration convention; do not count the same stop again. |
| Quality | Startup rejects; production rejects | Keep total and accepted quantity on the same product basis. |
A reason code should explain an observed event: “label roll change” is more useful than “operator issue.” Define when an event starts and ends, who records it and how concurrent events are assigned. For a line, decide whether a downstream stop is the originating cause or only the visible symptom.
Reconcile time before ranking causes
Fictional manufacturing teaching example. These figures are not ORDREL customer results.
Use the 450 planned minutes, 405 running minutes, 750 total units, 720 good units and ideal rate of 2 units/minute from the OEE worked example. Stop reasons are 20 minutes of adjustment, 15 minutes of material interruption and 10 minutes awaiting an approved restart. Their total is 45 minutes.
Net time at the ideal rate is 750 ÷ 2 = 375 minutes. Performance loss is 405 − 375 = 30 minutes. Reject-equivalent loss is (750 − 720) ÷ 2 = 15 minutes. Add 45 + 30 + 15 + 360 good-equivalent minutes = 450. If the reason log totals 50 minutes, fix the overlapping five minutes before interpreting the chart.
The stop log does not prove the reason for the speed loss. Observe the running process separately; do not allocate all unexplained time to the most convenient reason code.
Why utilization and OEE can tell different stories
Define schedule utilization here as planned production time divided by the entire comparison window. Other businesses use “utilization” for different ratios, so always write the denominator.
In a fictional 24-hour day with 450 planned production minutes, utilization = 450 ÷ 1,440 = 31.25%. If OEE is 80%, TEEP = 0.80 × 0.3125 = 25%. Equivalently, 360 good-equivalent minutes ÷ 1,440 minutes = 25%.
ORDREL’s OEE tool calculates planned-time effectiveness, not a separate calendar-utilization or TEEP report. This extension is a worked calculation in this guide. A low calendar ratio is not a recommendation to run additional shifts without demand, maintenance, staffing and cost evidence.
Set targets from the constraint and the loss
Start from your own consistent baseline, the customer requirement and the specific recoverable loss. An often-quoted industry percentage is not a universal acceptance criterion. Product mix, the chosen boundary and exclusion rules can make comparisons misleading.
For example, eliminating ten stopped minutes only creates potential. The realized output depends on whether the line can run at the assumed rate, whether quality holds and whether another process constrains it. Record the assumption and compare equivalent periods after the trial. Do not describe hypothetical output as achieved savings.
Use the data without double counting
In the OEE tool, record reason minutes that reconcile to stop time. Review the factor breakdown, then use the Pareto tool for comparable loss categories. Keep counts, minutes and money in separate analyses.
- Is a changeover planned or excluded? A planned stop can still be an availability loss when production is expected in that period. Use a documented policy consistently.
- Can an OEE increase hide a problem? Yes. A denominator change or lower quality alongside higher availability deserves review.
- Can reasons overlap? Real events can; the accounting must assign each lost minute once. Retain a separate narrative when several causes contribute.
Sources and method notes
Sources support the method definitions. Examples, interpretation and tool instructions are ORDREL teaching material, not an endorsement by the referenced organizations. See methods and corrections.