That Day the OEE Report Came Out, and the Boss Frowned for Three Seconds
I remember one time, the OEE report for the production line came out, and the numbers were excellent, reaching 85%! After seeing it, the boss's brow furrowed, and he asked, "Do you really think this is sustainable?" At the time, I thought, 85% OEE, that's quite good in the industry, isn't it? The boss then pointed to the "Planned Downtime" column on the report and calmly said, "You've scheduled all the equipment downtime for Saturdays; of course, the OEE looks good this way." Suddenly, the entire meeting room fell silent, everyone exchanged glances, thinking, "Oh, right, that's a clever trick, but does it really reflect the equipment's true productivity?"
What's the Problem? OEE's Sweet Traps
To put it bluntly, OEE (Overall Equipment Effectiveness) is a metric that, much like financial reports, offers ample room for "beautification." It restricts the calculation of equipment availability to "within scheduled operating hours." Therefore, if you schedule all preventive maintenance, mold changes, and even line cleaning for "non-working hours," the OEE figures during working hours will naturally appear very impressive. This is like only taking an exam on topics you're good at; of course, your score will be high!
So the key point is, while OEE is important, it cannot fully reflect the equipment's "potential productivity." It allows us to overlook downtime outside of scheduled shifts, making us believe the equipment is continuously running at high efficiency. But in reality, if equipment is available for 168 hours a week, and we only use it for 100 hours, what about the remaining 68 hours? Should that not be considered a loss?
TEEP Tells You the Equipment's "True Potential"
At this point, we need to introduce the TEEP (Total Effective Equipment Performance) metric. Frankly speaking, TEEP's calculation method is actually more "brutal" than OEE's; it doesn't care how many hours you schedule for shifts. It directly uses "168 hours a week" as the maximum available time for the equipment in its calculation.
In other words:
- TEEP's time base is 24 hours x 7 days = 168 hours.
- OEE's time base is your "scheduled operating time."
Let's take an example: Suppose your equipment is scheduled for 120 hours a week, and its OEE reaches 85%.
However, if we look at it from a TEEP perspective, even if your equipment is highly efficient during scheduled hours, but you only used it for 120 hours, the TEEP will definitely be much lower than the OEE.
Assuming production efficiency and quality are the same, then TEEP = (120 hours * 85%) / 168 hours = 60.7%. See, that's a big difference, isn't it?
Therefore, TEEP can more truly reflect your equipment's utilization rate under "extreme conditions."
The Most Common Pitfall: Just Aiming for Good-Looking Numbers?
The most common pitfall I've encountered is solely pursuing impressive OEE figures. Some factory managers, to meet targets, will push all "planned downtime" into non-scheduled hours. For instance, if weekly maintenance originally required 4 hours of downtime, to avoid impacting OEE, these 4 hours would be scheduled for Saturdays and Sundays. Superficially, OEE might jump from 75% to 80%, making the boss happy.
But honestly, this is just "self-deception." Equipment still needs maintenance when it's due, and molds still need changing. This time doesn't disappear; it's merely "shifted." If new orders come in, requiring overtime production, these "hidden" downtimes will instantly become your bottleneck. At that point, you'll realize that the equipment's true capacity isn't that high at all, and boosting output is simply impossible – truly a situation where you want to cry but have no tears.
One Thing You Can Do Today
Try re-examining the "planned downtime" in your OEE reports from a TEEP perspective.