OEE (Overall Equipment Effectiveness) measures how well a machine or process uses its planned time. It splits the gap between perfect production and actual production into three factors, so you can see where the losses come from.
The formula#
| Factor | Formula | Loss it shows |
|---|---|---|
| Availability | Run time / Planned production time | Breakdowns, changeovers, waiting for material |
| Performance | (Ideal cycle time × Total count) / Run time | Slow running, small stops |
| Quality | Good count / Total count | Defects and rework |
Worked example: an automatic pocket setter#
A pocket setting machine is planned to run for 480 minutes. It has an ideal cycle time of 0.25 minutes per piece.
- Downtime: 40 minutes breakdown, 20 minutes changeover. Run time = 480 - 60 = 420 minutes.
- Total pieces produced: 1,400.
- Good pieces: 1,330.
Calculations:
- Availability = 420 / 480 = 87.5%
- Performance = (0.25 × 1,400) / 420 = 350 / 420 = 83.3%
- Quality = 1,330 / 1,400 = 95.0%
- OEE = 0.875 × 0.833 × 0.950 = 69.3%
The biggest losses are performance (slow running, small stops) and availability. That tells the maintenance and engineering team where to look first.
Where OEE fits in a garment factory#
OEE was developed for machine-paced processes. In garment factories, it fits best where a machine sets the pace:
- Knitting machines (circular and flat).
- Automatic sewing units (pocket setters, automatic hemmers, placket units).
- Cutting machines (automatic cutters, spreading machines).
- Embroidery and printing machines.
On manual sewing lines, the operator mostly sets the pace. There, line efficiency is the usual measure. You can still apply the OEE loss categories to a sewing line to organise losses:
| OEE loss | Sewing line example |
|---|---|
| Availability | Machine breakdowns, waiting for cut parts or trims, style changeover |
| Performance | Operators below standard pace, small stops for thread changes |
| Quality | Repairs, rejects |
OEE compared with line efficiency#
| OEE | Line efficiency | |
|---|---|---|
| Base | Machine planned time | Operator available minutes |
| Standard | Ideal machine cycle time | SMV |
| Quality | Included as a factor | Usually counted only if output is "good" output |
| Best use | Machine-paced processes | Labour-paced sewing lines |
Common mistakes#
- Using a slow cycle time as "ideal", which makes performance look high.
- Excluding changeovers from planned time, which hides a large availability loss.
- Reporting only the OEE number without the three factors. The factors show what to fix.
- Comparing OEE across very different machines as if they were the same.
Use the OEE calculator to run the numbers and see which factor is lowest.
Collecting OEE data#
OEE is only as good as the data behind it. For each machine or cell, record per shift:
| Data | Source |
|---|---|
| Planned production time | Shift plan, minus planned breaks |
| Downtime events with reasons | Machine log, operator sheet or machine counter |
| Total count | Machine counter or production record |
| Good count | Quality records after inspection |
| Ideal cycle time | Machine specification or best demonstrated rate for the product |
Group downtime reasons into a short list (breakdown, changeover, material waiting, no operator, quality stop) so the data can be summarised quickly. Review the top losses weekly with maintenance and production.
Related guides#
- Low line efficiency: the loss categories on labour-paced sewing lines.
- Lean manufacturing in garments: how OEE fits into a lean improvement program.
- Bottleneck analysis: finding which machine limits output.
- Sewing machine types: the automatic units where OEE is most useful.
- Kaizen: small improvements that raise availability and performance.
Frequently asked questions#
What is a good OEE? It depends on the process, product mix and how strictly the losses are defined. Use OEE to track improvement on the same machine over time, rather than comparing with a published figure.
Should planned maintenance count as downtime? Many companies exclude planned maintenance from planned production time. Decide the rule, write it down, and apply it consistently.
Can OEE be above 100%? Not if the ideal cycle time is correct. A result above 100% usually means the ideal cycle time is set too slow.