Also called TRG
What is overall equipment effectiveness?
One number for how much good product a machine made against what it could have made if it never stopped, slowed or scrapped.
What else it is called
- Other names
- TRG
- In French
- taux de rendement global
Related entries
Understanding overall equipment effectiveness
Availability multiplied by performance multiplied by quality, each expressed as a proportion. The three are multiplied, not averaged, so the number falls fast. That is deliberate. Losses in three places compound, and a plant losing a little at each of them is losing a lot in total.
The reason to insist on the three components is that they point at different departments. Sixty-five per cent caused by changeovers and breakdowns is a maintenance and scheduling problem. The same 65 per cent caused by running below rated speed is an engineering or training problem. The same 65 per cent caused by scrap is a quality problem. One number cannot tell you which, so a plant reporting only the headline figure has bought the overhead of measuring without the benefit.
One honest warning: the measure applies to a constraint machine. Improving the score on equipment that is not the bottleneck produces a better number and no additional shipments.
How it is calculated
Overall equipment effectiveness = availability × performance × quality
Availability is run time divided by planned production time. Performance is actual output divided by what the ideal cycle time would have produced in that run time. Quality is good parts divided by total parts made.
In practice
Always ask for the three components. The plants that improve are the ones tracking which of the three is costing them the most this month, not the ones reporting one number to head office.
Frequently asked
What is a good overall equipment effectiveness score?
Eighty-five per cent is the figure usually quoted as world class for discrete manufacturing, and it is a demanding target. More useful than the benchmark is your own trend on one machine, measured the same way each month, because the definitions vary enough between plants that comparing your number to somebody else’s tells you very little.
Does planned downtime count against availability?
No. Planned maintenance, breaks and days with no scheduled production come out of the denominator - the measure is against planned production time, not the calendar. Including them produces a low number that cannot be improved, which is how plants end up ignoring the metric.
Is overall equipment effectiveness worth measuring on every machine?
No. Measure it on the constraint, and on anything you are considering replacing. Measuring it everywhere costs data-collection effort on equipment whose improvement would not change output.