Three factors, three different problems.
Each OEE factor has its own cause, owner and fix — and the product of the three conceals all of them. What a poor score in each actually means.
Low A, high P, high Q: it stops a lot but runs well when running. Look at changeovers, breakdowns, materials and manning, not feeds and speeds.
- Availability, performance and quality are three separate diagnostics with different causes, owners and fixes; the OEE product conceals which one you have.
- Performance is only as good as the ideal cycle time behind it, and a quality figure of exactly 100% usually means rejections are not being captured.
- Low availability means stops, low performance means slow running or micro-stops, and low quality with high A and P means scrap produced efficiently.
The three OEE factors are usually presented as parts of one calculation. They are better understood as three separate diagnostics that happen to be multiplied together — because each has a different cause, a different owner and a different fix, and the product conceals all three.
This article takes each in turn: what it measures, what corrupts it, and what a poor score actually means.
ISO: actual production time ÷ planned production time. MachineWise variant: machine on-time ÷ reporting time.
Availability is the factor most plants find easiest to accept and most often compute wrongly, for one reason: the boundary between planned and unplanned. Scheduled breaks, planned maintenance and a shift you chose not to run are not availability losses. Setup is the contested case — a machine being changed over is not broken, and treating it as downtime produces a figure the shop floor rejects on sight.
A poor availability score means the machine is stopping. The fix lives with maintenance, scheduling and materials, and the diagnosis is a Pareto of stop reasons rather than anything about the machine's speed. If availability is your weak factor, cycle times and tooling are not your problem this month.
ISO Effectiveness: (produced quantity × ideal cycle time) ÷ actual production time. MachineWise variant: productive time ÷ machine on-time, a time-in-cut proxy.
Performance is the factor most often meaningless, because it depends entirely on the ideal cycle time — and on most Indian job-shop floors that standard is absent, stale or was optimistic when it was set. An ISO Effectiveness figure computed from a bad standard is precise and worthless, and it is frequently the figure quoted because it tends to look flattering.
A poor performance score means the machine is running but not producing at rate. Causes divide into speed losses — conservative feeds and speeds, worn tooling, material variation — and small stops too brief to have been classified as downtime. The two have different owners, which is why short-stop detection matters: without it, micro-stops silently become a performance problem and are investigated as a speed problem.
ISO: good quantity ÷ produced quantity. The MachineWise variant is identical, because there is nothing to improve on here.
Quality is the simplest factor and the one most often reported as exactly 100%, which should be read as a warning rather than an achievement. A machine control counts cycles, not acceptable components. Unless rejections are captured and subtracted, Quality reads perfect and Performance is flattered by the time spent producing scrap.
A poor quality score is the most expensive of the three, because a rejected part consumed availability, performance, material and labour before being discarded. It is also the factor where the first rework pass should be decided explicitly: a component reworked to acceptance is not a good part first time, and whether you count it as one changes both the number and the behaviour it encourages.
| Pattern | What it indicates | Where to look |
|---|---|---|
| Low A, high P, high Q | The machine stops a lot but runs well when running | Changeovers, breakdowns, material and manning |
| High A, low P, high Q | The machine runs almost continuously but slowly | Feeds and speeds, tooling, micro-stops, or a wrong standard |
| High A, high P, low Q | Producing scrap efficiently — the most costly pattern | Process capability, tool condition, incoming material |
| Low A, low P | Usually one cause presenting twice | Investigate availability first; performance often recovers with it |
| All three high, dispatch still missed | OEE is not the problem | Scheduling and sequence — see production monitoring |
| Factor | ISO 22400-2 — the standard | MachineWise variant — internal only |
|---|---|---|
| Availability | Actual production time ÷ planned production time | Machine on-time ÷ reporting time |
| Performance / Effectiveness | (Produced quantity × ideal cycle time) ÷ actual production time | Productive time ÷ machine on-time — a time-in-cut proxy |
| Quality | Good quantity ÷ produced quantity | Identical to ISO |
| Needs a maintained standard? | Yes — an ideal cycle time per part | No |
| Comparable to published benchmarks? | Yes | No — treat as your own baseline |
The variant exists because a floor running fifty part numbers a month often has no trustworthy ideal cycle time, and an OEE that cannot be computed until standards are maintained is an OEE that never gets computed. It is useful internally and it is not the ISO definition. Quote the ISO figure externally, and say which one you used.
See your own availability, performance and quality
Measured per machine and per shift, on the ISO 22400-2 basis or the internal variant, with the definition stated beside every figure.