OEE Loss Pareto Worksheet by Reason Code
A Pareto of losses answers the question every OEE program has to settle: which problem do we fix first. This worksheet gives you a table to rank loss reasons by minutes and by cost, then pick the few that deserve a team.
| Loss reason | Loss category | Events | Minutes lost | Minutes per event | Cost per minute | Estimated cost | |
|---|---|---|---|---|---|---|---|
77.5 | $6,820 | ||||||
60 | $11,880 | ||||||
34.1667 | $4,510 | ||||||
3.3333 | $3,520 | ||||||
23.3333 | $6,160 | ||||||
6.3333 | $2,090 |
Sort the rows by minutes lost, largest first, and work down the list until you reach about eighty percent of the total. Use one cost per minute for the constrained machine, such as contribution margin per run minute, not the full standard cost.
Build a live loss Pareto
Optional: we can look at where your downtime and scrap reasons are stored and outline a daily updated Pareto.
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How to use the worksheet
Export last month of downtime and scrap records from your MES, ERP or paper log and group them by reason code. Enter one row per reason with the number of events and total minutes lost. The sheet calculates the average minutes per event and the estimated cost. Sort by minutes, mark the reasons that make up the first eighty percent, and review the average minutes per event: high per event suggests a few big failures, low per event with high counts suggests chronic small problems.
The Pareto principle in plant data
Loss data is usually uneven. A handful of reasons explains most of the lost time, which is why ranking beats general effort. Always rank twice, once by minutes and once by events, because a reason that stops the line often but briefly needs a different approach than one that stops it rarely but for hours. Compare categories as well as reasons, since five different changeover codes may together be the real top item.
- Rank by minutes lost, then by events
- Group similar codes into one category before ranking
- Review the Other and Unknown rows, they hide opportunity
Putting a cost on each loss
Time becomes persuasive when it has a price. On a bottleneck machine, each lost minute costs the contribution margin of the parts you could have made. On a non-bottleneck, the real cost may be overtime or a missed delivery. Enter the cost per minute that fits your situation and be ready to explain it. The estimated cost column is meant for ranking, not for the accounting books, so a rough and consistent number is better than a precise and disputed one.
Common mistakes
Teams often attack the biggest bar without checking whether the data is trustworthy. If a quarter of the minutes sit under Other, the chart is not yet reliable. Another trap is mixing planned stops with unplanned losses, which pushes meetings to the top and hides breakdowns. Keep planned stops in their own category and filter them when you want the improvement view. Finally, re-run the Pareto after each fix, because the order changes.
Frequently Asked Questions
How many reason codes should I have?
Between ten and thirty is typical. Too few hides causes, too many splits the data until nothing stands out. Review the codes once a quarter, merge rarely used ones, and keep the Other share under about ten percent.
Should I rank by minutes or by cost?
Start with minutes, then check cost if machines have very different value. If all rows use the same cost per minute the order is identical. Cost matters when you mix bottleneck and non-bottleneck equipment.
Does the worksheet draw the chart?
The worksheet gives you the ranked table with totals and the largest share. Export to Excel and add a bar chart there if you need the visual for a report. The data columns are already laid out for that.
Can quality losses go in the same table?
Yes, if you convert scrap into equivalent minutes by dividing scrapped units by the ideal rate. That keeps all OEE losses in the same unit and lets you compare a defect with a breakdown on one list.
If your downtime reasons are stored in an ERP or MES, we can build a live Pareto that updates daily instead of a monthly spreadsheet exercise.
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