OEE — calculation, six big losses and downtime analysis — Industry 4.0 & IIoT

5. OEE — calculation, six big losses and downtime analysis

Intermediate★ Must knowLesson 5 of 10

OEE (Overall Equipment Effectiveness) = Availability × Performance × Quality

Factor	Formula	Loss it captures
Availability	Run time ÷ Planned production time	Breakdowns, changeovers, waiting
Performance	(Ideal cycle time × Total count) ÷ Run time	Slow cycles, minor stops
Quality	Good count ÷ Total count	Scrap, rework, start-up rejects

Worked example (one shift): planned time 480 min; downtime 60 min → run time 420 min → Availability = 87.5 %. Ideal cycle time 1.0 min/part; 380 parts produced → Performance = 380 ÷ 420 = 90.5 %. 361 good parts → Quality = 95 %. OEE = 0.875 × 0.905 × 0.95 ≈ 75.2 %. (World-class benchmark often quoted ≈ 85 %; many plants start at 40–60 %.)

Six big losses (TPM): breakdowns, setup/adjustments (→ availability); small stops, reduced speed (→ performance); start-up rejects, production rejects (→ quality).

sql

-- OEE per line per shift from MES tables (simplified)
SELECT  s.LineId, s.ShiftDate, s.Shift,
        Availability = CAST(s.RunMinutes AS float) / NULLIF(s.PlannedMinutes, 0),
        Performance  = (s.IdealCycleMin * s.TotalCount) / NULLIF(s.RunMinutes, 0),
        Quality      = CAST(s.GoodCount AS float) / NULLIF(s.TotalCount, 0),
        OEE          = (CAST(s.RunMinutes AS float) / NULLIF(s.PlannedMinutes, 0))
                     * ((s.IdealCycleMin * s.TotalCount) / NULLIF(s.RunMinutes, 0))
                     * (CAST(s.GoodCount AS float) / NULLIF(s.TotalCount, 0))
FROM mes.ShiftSummary s;

Other KPIs: MTBF (mean time between failures), MTTR (mean time to repair), throughput, first pass yield (FPY), scrap rate, cycle time, takt time (available time ÷ customer demand), energy per unit, schedule adherence.