Having explained in the first part of “What is a Robust Process”, I ended by saying that OEE is a good indicator of understanding the “health” of a production facility.
Overall Equipment Efficiency (OEE) is a measure of the ability of a machine to consistently produce a product which meets quality standards at the designed cycle rate without disruption.
World-class standards aim for an OEE of or above 85%. So what makes up OEE?
OEE measures three key indicators - these are made up of other key measurable such as Dock To Dock (DTD), Build To Schedule (BTS) and First Time Through (FTT), but let’s look at the top levels which are:
• Equipment Availability
• Performance Efficiency
• Quality Performance
Looking at these three key areas we can therefore express that:
OEE = Availability x Performance Efficiency x Quality Rate
Where AVAILABILITY is the amount of time the machine or process was available to run compared to the amount of time it was scheduled to run. Therefore:
Availability = Operating Time / Net Available Time
PERFORMANCE EFFICIENCY determines how closely a piece of equipment runs to its planned cycle time. This can be affected by speed losses and losses associated with undocumented idling or minor stoppages resulting from blocked or starved upstream or downstream equipment. If possible this should be logged if it is having an impact on key equipment performance efficiency. Therefore:
Performance Efficiency = (Planned Cycle Time x Total Products Run) / Operating Time
Finally, QUALITY RATE is the total number of good parts produced on a machine or operation compared to the total products run, or:
Quality Rate = (Total Products Run – Total Rejects) / Total Products Run
To summarise: a process should achieve 85% or more to be classed as a Robust Process.
If you have attended the Core Tools training you will know that you can derive various data sheets to capture supporting data to help with the above. This blog is not about teaching OEE as such, but should further knowledge about OEE please consider our Manufacturing Excellence (Lean Manufacturing) training.
Next, I will focus on quality performance indicators...
Written by:
Matthew Woodford (ht+a Trainer & Consultant)
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