Flawless Execution – Performance to Plan
Overall Equipment Effectiveness, OEE, is as much about “when” as it is about “how”. The objective of OEE is to identify opportunities that enable us to maximize the time available to produce quality parts at rate – the ideal cycle time. This ultimately affects our ability to predict when production should start and finish in kind.
Having a plan and executing a plan are far from being one and the same. Having a plan suggests that we already understand where “losses” are expected to occur. As such, our ability to execute according to plan is the difference between predictive performance expectations and actual performance results.
The variance between expected and actual results directly correlates to how well we understand our processes – regardless of outcome. In this same context, the degree of variance observed should also be reflected in the results of our OEE.
This becomes relevant when we consider where we think improvements are required. If we are unable to predict or anticipate the performance of our processes in their current state, how is it possible to truly identify the return on investment for incremental improvements in the future?
Statistical Process Control (SPC)
How much variance do you observe in the results of your OEE from one run to another? I wrote a post several years ago titled “Variance, OEE’s Silent Partner (Killer)“, that discusses this concept in greater depth.
The key to improving OEE begins by eliminating the excess variance in the results. In other words, to control OEE requires us to eliminate the sources of variation. When the results become predictable, the opportunity to control OEE begins.
Availability is typically the greatest contributor to observed differences in OEE. The primary reasons typically include unexpected machine faults and / or process failures. An effective preventive maintenance program will minimize and eventually eliminate the effect of “unexpected” downtime events on your OEE results.
There is more to process performance than monitoring downtime events, speed, and first time through quality levels. Performance to plan extends the concept to include whether parts are running when they were actually scheduled to run.
Predictable processes provide for greater flexibility in scheduling as do efforts to reduce setup / change over times and increase throughput. Toyota’s Heijunka box, a visual scheduling and optimization methodology, relies heavily on predictable process performance and short setup / change over times.
Just in time manufacturing demands unparalleled performance that can be enhanced by using OEE as a key indicator in your production operations.
Until Next Time – STAY lean!