Existing operations · Performance

Measure OEE losses before you buy new equipment

Q: What is a good OEE?

There is no universal good value; it depends on product mix, changeover frequency and how planned time is defined. Compare a line against its own best sustained performance and against the output it must deliver.

Q: Should I calculate OEE per machine or per line?

Both. Line OEE shows delivered performance; machine-level data shows which step causes the losses. Upgrade decisions should be made at the constraint step.

Q: Can OEE justify buying a new machine?

Only indirectly. OEE shows where time is lost. Investment is justified when the remaining gap after realistic loss reduction still prevents you from meeting demand or cost targets.

A loss baseline tells you whether you need a new machine, a retrofit, or better changeovers. It is the cheapest engineering study a plant can run.

By the Global B2B Group project teamPublished 2026-10-169 min read

Production supervisor with a stopwatch and clipboard reviewing an OEE downtime dashboard beside a running bottling line

Short answer

OEE = Availability × Performance × Quality, measured against planned production time. Break each factor into named losses (breakdowns, changeovers, minor stops, slow running, start-up rejects, process rejects), record them for at least several weeks, and fix the largest loss on the constraint step first. Buy capacity only for the gap that remains after realistic loss reduction.

Request a line upgrade assessment Diagnose a plant problem

Who is asking — and what each role should check first

Role	Their question	Start with
Owner / managing director	Is this worth the capital and the disruption risk?	Payback range, downside case, and what happens if we do nothing.
Operations / plant manager	Will this fix the losses I see every shift?	Loss baseline by category and the shutdown window the plant can afford.
Engineer / maintenance	Can it be integrated, maintained and made safe?	Interfaces, utilities, controls obsolescence and the safety re-assessment.
Purchasing	Are we comparing offers on the same scope?	One written requirement, a normalised scope matrix and acceptance terms.
Consultant / advisor	Is the business case built on measured data?	Data quality, assumptions register and sensitivity on the key drivers.

What OEE measures — and what it does not

OEE shows how much of the planned time on one asset or line produced good output at the ideal rate. It does not show whether that asset is the plant's constraint.

Availability

Run time ÷ Planned production time

Planned production time excludes scheduled no-production periods; define them once and keep them fixed.

Performance

(Ideal cycle time × Total count) ÷ Run time

Use the validated ideal cycle time for the product, not the nameplate maximum of a different format.

Quality

Good count ÷ Total count

Count rework as not-good at first pass, or the losses disappear from the data.

OEE

Availability × Performance × Quality = (Good count × Ideal cycle time) ÷ Planned production time

ISO 22400-2 defines comparable KPIs; agree one definition across sites before benchmarking.

Turn the OEE number into a loss tree

A single OEE percentage is not actionable. A ranked list of losses in hours or units is.

Loss categories and the upgrade they point to (original GBG mapping)
Loss	OEE factor	Typical evidence	Usually first fix	Equipment spend justified when
Breakdowns	Availability	Repeat failure codes, MTBF trend	Root cause + preventive maintenance	Failures trace to wear or obsolete parts
Changeovers / setups	Availability	Setup time per format	SMED-style setup reduction	Tooling or format parts are the limit
Minor stops / jams	Performance	Short stops < 5 min per hour	Infeed, sensors, material spec	Mechanism design causes the jams
Reduced speed	Performance	Actual vs ideal rate	Recipe and upstream supply check	Drive, servo or controls cannot hold rate
Start-up rejects	Quality	Rejects after each start	Warm-up procedure	Process control cannot stabilise
Process rejects	Quality	Reject causes by shift	Inspection + material control	Precision or sealing capability is short

How much data is enough

Cover every product format and shift pattern that matters — several weeks is a practical minimum; a full product cycle is better.
Use reason codes the operators can actually choose in under five seconds; too many codes produce 'other'.
Reconcile counts with dispatched good output weekly, so the data is trusted by finance.
Record the step that was starved or blocked, not just the step that stopped.

Size the upgrade from the remaining gap

Required capacity gap = target good output − (current good output after realistic loss reduction).

Recoverable output

Planned time × Ideal rate × (Target OEE − Current OEE)

Use a target you can defend from your own best sustained weeks, not an industry headline.

Illustrative example — hypothetical line, not client data
Item	Value
Planned time per year	5,000 h
Ideal rate	3,000 units/h
Current OEE	55% → 8.25 M good units/yr
Best sustained 4 weeks	65% → 9.75 M good units/yr
Demand target	11.0 M good units/yr
Gap after loss reduction	1.25 M units/yr — this, not 2.75 M, is what new capacity must cover

Mistakes to avoid

Comparing OEE across plants that define planned time differently.
Buying a faster machine for a step that is not the constraint.
Using supplier nameplate speed as the ideal cycle time in the business case.
Ignoring ramp-up: a new or retrofitted asset rarely reaches target in the first weeks; put a ramp-up curve in the ROI model.

Frequently asked questions

What is a good OEE?

There is no universal good value; it depends on product mix, changeover frequency and how planned time is defined. Compare a line against its own best sustained performance and against the output it must deliver.

Should I calculate OEE per machine or per line?

Both. Line OEE shows delivered performance; machine-level data shows which step causes the losses. Upgrade decisions should be made at the constraint step.

Can OEE justify buying a new machine?

Only indirectly. OEE shows where time is lost. Investment is justified when the remaining gap after realistic loss reduction still prevents you from meeting demand or cost targets.

Request a line upgrade assessment

Share your loss data or current output and target. The team reviews it as an upgrade of an existing line. Planning guides and calculators are free; supplier outreach applies to qualified projects of USD 250,000 or more.

Start the request

Sources and references

ISO 22400-2:2014 — KPI definitions for manufacturing operations management, including OEE index.
Nakajima, S. — Introduction to TPM (1988) — Origin of the six big losses grouping used above.
Goldratt, E. — The Goal (1984) — Theory of constraints: throughput is limited by the constraint step.

Example figures are hypothetical and illustrate method only; they are not client results or price quotes.