OEE highlights the “major losses” in the manufacturing process for focused improvement. It can then be used to measure the effect of efforts or initiatives introduced to reduce the major losses and thereby tap “hidden capacity”.
To improve OEE you need to focus on the three elements of the OEE formula - Availability, Performance and Quality. Each of these elements are considered below along with typical factors affecting them.
Availability can be stated as the percentage of time machines or equipment is actually running when it is scheduled to run.
Availability = (Available Time – Unplanned Downtime x 100%)/(Total Available Time – Planned Downtime)
Equipment run time availability is affected by both planned/scheduled downtime and unplanned/unscheduled downtime.
Planned or scheduled downtime loss factors include;
- No Production Scheduled - Excess capacity
- Planned breaks
- Planned Maintenance
- Communications briefs / team meetings
Unplanned downtime loss factors include;
- Breakdowns and failures
- Changeover (product size etc)
- Late deliveries (materials)
- Operator availability
- Tooling or part changes
- Start up or adjustment
Performance can be stated as the difference between the potential output and actual output, when the equipment was available.
Performance = (Ideal Cycle Time x Actual Output* x 100%)/Available Operating Time
*Actual Output is the quantity of good & bad parts
Performance rate loss factors include;
- Idling & short stoppages (jams, circuit breaker trips etc.)
- Reduced speed, cycle time or capacity
Quality can be stated as the total good parts or units produced expressed as a percentage of the total parts produced.
Quality = (Parts Made – Defect Quantity x 100%)/Parts Made
Quality rate loss factors include:
- Scrap, defects, rework
- Variability of raw materials
- Start up losses
- Equipment and tooling faults, inaccuracies etc.
Implementing a PlantRun system provides you with the tools you need to automate OEE data collection, reporting and analysis, pinpoint where the losses are occurring so you know where to target resources and track the progress of any initiatives to improve OEE.
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