Of course, in hindsight, it made perfect sense. Efficiency was measured as the number of parts you made divided by the estimated number of part you could make, base upon the cycle time of the machine. The bottleneck was the operation that most restricted flow, so it was rarely blocked or starved. So the bottleneck efficiency was high – a “hand grenade close” estimate was taking the downtime percent and subtracting it from 100%.
Faster machines could, according to their cycle time, produce more parts than the bottleneck. In reality, they spend a lot of their time waiting for Herbie – blocked or starved, as well as down. Over time, they made no more parts than the bottleneck, but had a higher capacity, thus their efficiency had to be lower.
And the two machines we were studying? I dubbed them the “anti-bottlenecks” – the fastest machines in the plant! The stock cutting machines was really fast – it ran hundreds of parts in an hour. The press, too, had a cycle time of a few seconds. The bottleneck cycle time was just under 60 seconds, so these machines were several times faster than the constraint.
And what was the biggest delay for both of these machines? If you guess “Waiting for baskets,” go out an buy that cupie doll you have always wanted. What, then, was the action plan to improve the efficiency of this plant? Buy more baskets!!!
But I had a hard lesson to learn that day myself. After collecting the data from delay studies and a quick study on the bottleneck, I entered into the bottleneck analysis program C-Thru. Of course, it confirmed my analysis, and demonstrated that improving the stock cutter and the press would have no impact on throughput or efficiency. Further, buying more baskets would only improve efficiency during the time it took to fill those baskets. After that, efficiency would return to today’s level.
Fixing the bottleneck, however, would have a huge impact on throughput. That area had to be the focus of improvements. Studying the bulletin board further, I found that most of the action plans resulting in INCREASING the cycle time of the constraint, thus reducing what little blocking and starving there was, AND increasing efficiency. Of course, throughput for the plant went down as well, but that was not obvious to them. It was clear to me that those changes would have to be removed.
Armed with my analysis, I went to the plant sponsor (who was also the efficiency program champion) and, in front of my folks and the other central office people there “to help” told them he was doing EXACTLY the wrong thing. This program was damaging the plant, not helping it. He would have to undo all those award-winning suggestions on the bottleneck. He would have to stop worrying about the least efficient machines and focus the plant’s efforts on the most efficient machine.
I think he listened for about a minute and then tuned me out. After my report out, he thanked me for my analysis, and said that they were going to continue push the efficiency program as the way to save the plant. I was stunned. All I could think to say was, “Then I come by on the day they close the plant.” He gave me a funny look, shook his head, and left.
Of course, the plant’s performance continued to suffer, until the plant was eventually sold. It then closed, but not officially under the GM logo. For a while, I blamed the sponsor’s ignorance and politics for not following my advice But after going through Jonah training and Clouds, I realized that in my rush to tell him the answer (and prove myself right, of course) I had not resolved his conflict. That was a tough lesson. Could I have saved the plant? Probably not – those skills and experience would come with time, and much of my learning at this point in my career with TOC was trial and error. But I still wonder about it just the same.
I use this example in my training classes all the time, for it reinforces several key points:
The bottleneck is usually the most efficient machine (or has the highest utilization or highest OEE). I often use this as a quick quiz to see if someone really understands TOC as much as they say they do.
Use inventory to find the bottleneck, especially the first time through.
You have to understand the conflict your client faces to be able to solve it for him, thus shifting his paradigm to one that includes your solution.
Efficiency measures have a very limited usefulness, and probably could be set aside, for all intents and purposes.
You have the ability to save your plant, or elevate it to the next level or performance. And it’s your job to do that, so don’t wait for someone to tell you it’s your job.