OEE Definition | Calculation | Formula | Examples | Lean Tool
What is OEE (Overall Equipment Effectiveness)?
→ OEE (Overall Equipment Effectiveness) is an index to judge production run in terms of machine (equipment) availability, Production rate & quality of the product.→ For TPM (Total Productive Maintenance) and Lean Manufacturing programs, OEE is key matric.
→ It is an important characteristic of capacity planning, material planning, and other resource planning.
→ OEE is also known as TEEP (Total effective equipment performance).
→ Overall Equipment Effectiveness is a Lean Manufacturing Tool.
Basics of OEE (Overall Equipment Effectiveness)
→ There are three parameters for OEE (Overall Equipment Effectiveness) monitoring- Availability
- Performance
- Quality
➤ [1] Availability:
→ Availability shows the available time of the machine.→ In other words, for how much time our machine is available for production.
→ Availability takes into account of Down Time Losses.
→ Downtime losses include event or incidents that lead to stoppage of planned production for a considerable time.
→ After removing, downtime we can get operating time.
➥ Examples of Downtime:
- Equipment failure,
- Material shortage,
- Excess change over time, etc...
➤ [2] Performance:
→ Performance shows the excess time taken for the production as compared to standard operating time.→ The performance takes into account of Speed Losses.
→ The Speed Losses includes any factor that leads to operate production with more cycle time than maximum permissible.
➥ Examples of performance losses:
- Low speed of job loading/unloading,
- Fatigue of the operator,
- Excess cycle time in manual work, etc...
➤ [3] Quality:
→ Quality shows the good quality of the produced parts.→ It takes into account the quality losses (loss due to the production of a bad part).
→ Quality loss can only be present due to the production of a defective part or non-conforming part.
OEE Calculation:
OEE = Availability (A) x Performance (P) x Quality (Q)
→ Where,
→ Availability (A) = Actual Production Time/Planned Production Time
→ (Planned Production Time = Total Available Time – Planned Breaks)
→ (Actual Production Time = Planned Production Time – Stops)
→ Performance (P) = Actual Production Rate / Ideal Production Rate
→ (Actual Production Rate = Total Count / Total Run Time)
→ Quality (Q) = Good Parts / Total Parts Produced
➤ Times and Losses in OEE Calculation
→ Planned Shutdown – Not part of OEE (Overall Equipment Effectiveness) Calculation.
→ Down Time Loss - Operating Time to Planned Production Time ratio is called availability, when a process run without any stoppage there will be 100% availability.
→ Speed Loss – It is the ratio of net operating time to total operating time or it can be calculated by actual cycle time / ideal cycle time. When process run with maximum theoretical speed then performance will be 100%.
→ Quality Loss- it is the ratio of total good parts to a total part produced. When all produced parts are good then there will be 100% quality.
→ Down Time Loss - Operating Time to Planned Production Time ratio is called availability, when a process run without any stoppage there will be 100% availability.
→ Speed Loss – It is the ratio of net operating time to total operating time or it can be calculated by actual cycle time / ideal cycle time. When process run with maximum theoretical speed then performance will be 100%.
→ Quality Loss- it is the ratio of total good parts to a total part produced. When all produced parts are good then there will be 100% quality.
Example of OEE Calculation:
→ Let’s assume below data to understand OEE calculation→ Shift Duration = 8 Hours (480 Minutes)
→ Total Breaks = 55 Minutes
→ Down Time / Break Down = 40 Minutes
→ Ideal Production Rate = 1 Part per Minute
→ Total Part Produced = 350
→ Rejected Parts = 4
➨ Planned Production Time = Total Available Time – Planned Breaks
= 480 Minutes – 55 Minutes
= 425 Minutes
➨ Actual Production Time = Planned Production Time – stops (Downtimes)
= 425 Minutes – 40 Minutes
= 385 Minutes
➨ Availability (A) = Actual Production Time/Planned Production Time
= 385 / 425 Minutes
= 0.905
➨ Actual Production Rate = Total Count / Total Run Time
= 350 / 385
= 0.909
➨ Performance (P) = Actual Production Rate / Ideal Production Rate
= 0.909 / 1.0
= 0.909
➨ Quality (Q) = Good Parts / Total Parts Produced
= (350-4) / 350
= 0.988
➨ OEE = Availability (A) x Performance (P) x Quality (Q)
= 0.905 x 0.909 x 0.988
= 0.812 ~ 81.2 %
Six Big Losses of OEE
- Breakdowns
- Setup and Adjustment
- Small Stops
- Reduced Speed
- Start-up Rejects
- Production Rejects
➤ [1] Breakdowns:
→ The breakdown comes under the Category - Downtime Loss.→ Unplanned downtime elimination is critical.
→ Preventive maintenance is a key weapon to kill unplanned downtimes.
→ Root cause analysis can be done on severe downtimes.
→ Timely validation of tool is also important in order to prevent unplanned downtime.
→ Prediction of equipment failure is a key skill of engineering that helps a lot in the prevention of downtime.
➥ Examples of Breakdown Losses:
- Tooling Failure,
- Unplanned Maintenance,
- Equipment Failure,
- General Breakdowns, etc...
➤ [2] Setup and Adjustment:
→ Setup and Adjustment come under the Category - Downtime Loss.→ It is generally called time between the last good part produced before setup change and first good part produced after the changeover.
→ Tracking of adjustment time is very important in reducing this loss.
→ We can use the concept of SMED (Single Minute Exchange of Dies) for reducing the Setup and Adjustment time.
➥ Examples of Setup and Adjustment:
- Excess setup/change over time,
- Material shortage,
- Operator shortage,
- warm-up times, etc...
➤ [3] Small Stops:
→ Small Stops comes under the Category - Speed Loss.→ Recording of this type of loss is very difficult.
→ Cycle time analysis to be used to identify this type of loss.
→ Activity wise actual-time monitoring and micro-mapping of this data help in the identification of small stops and speed reduction.
➥ Examples of Small Stops:
- Component jam,
- Sensor blocked,
- Delivery blocked,
- Cleaning and Checking, etc...
➤ [4] Reduced Speed:
→ Reduced Speed comes under the Category - Speed Loss→ Recording of Reduced Speed losses is very difficult.
→ It can be recorded by Cycle time analysis.
➥ Examples of Reduced Speed:
- Poor planning,
- Machine wear and tear,
- Operator inefficiency,
- Under design capacity, etc...
➤ [5] Start-up Rejects:
→ Start-up Reject comes under the Category - Quality Loss.→ “First Time Right” concept to be adopted during each startup of production.
→ Effective use of production start-up check sheet can eliminate start-up rejects.
→ The process parameter setting plays a vital role in the manufacturing of the good part at the first time.
➥ Examples of the Start-up Rejects:
→ Damage,→ Scrap,
→ Rework,
→ Incorrect assembly, etc..
➤ [6] Production Rejects:
→ Production Reject comes under the Category - Quality Loss→ It is related to the rejection during the production
➥ Examples of the Production Rejects
→ Damage,→ Scrap,
→ Rework,
→ Incorrect assembly, etc...
Benefits of OEE:
→ It helps us to set goals for improvement, and track the progress.
→ OEE helps us to find inefficiencies in production.
→ It Provides us a benchmark data for the new process setup.
→ Overall Equipment Effectiveness helps to track progress in eliminating waste from a manufacturing process.
→ OEE helps us to find inefficiencies in production.
→ It Provides us a benchmark data for the new process setup.
→ Overall Equipment Effectiveness helps to track progress in eliminating waste from a manufacturing process.
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