It’s safe to say the kinds words, comments, and emails for my one piece flow video have far exceeded my expectations.
While most of the comments and feedback have been extremely positive there have been a few skeptics in the crowd. For the record, I love skeptics! Why? They push me to be better and to think. And thinking is good.
Well, as of this evening, my new friend Eric H., of the GrimReader blog, has laid down a mind blowingly excellent analysis of my every move in the video. Eric, as they say, has some serious eagle eyes!
Seems there are skeptics about. So I, hard-headed person that I am, watched the entire video again with a spreadsheet (similar data posted to my better half’s website).
How do we account for the ~60 second difference in the two processes? (Which I contend is the wrong comparison, more below).
Average time to fold:
Batch: 9 s
Lean: 8 s
Average time to stuff:
Batch: 4 s
Lean: 3 s
Average time to seal:
Batch: 2 s
Lean: 1 s
Average time to stuff:
Batch: 1 s
Lean: 1 s
So, over 10 repetitions, the lean method got a total of 10+10+10=30 seconds of advantage from the shorter time to fold, stuff, and seal.
Could the shorter fold time be due to thinner paper used the second time? Or to the fact that you seem to get better as you go (you start with times of 9-10 s, but end with times of 7-8 s). The shorter stuff and seal times, though, are due to the fact that you are already holding the item from the previous step. You gain 1 second each time from not having to find and pick it up. That’s part of the point, so I contend that it’s unfair to count those against you as if they were a parlor trick of some sort.
Still need to account for 30 seconds, though.
You lose between 2 and 5 seconds every time you move the pile around between steps. Also, you have to manage the pile several times during a task, something you don’t have to do nearly as much with OPF. This also has a factory corollary: storing, moving, retrieving, and looking for WIP.
But those are the wrong numbers to compare. The real advantage, though, is the fact that you are knocking out a complete product roughly every 15 seconds with OPF. Every 15 seconds, the lean manufacturer fills another order. Every 15 seconds, he has the opportunity to inspect WIP and final product for defects.
Heck, let’s even spot the batch production method the 3 second difference (most of which is legitimate gain) so that they both average 18 seconds. The lean producer would be still be fulfilling another order every 18 seconds. The Batch producer doesn’t get any orders filled until 3:47. What if they were hours rather than seconds? With 40 hours in a week, that means that the lean producer is shipping twice a week while the batcher is shipping every 6 weeks. Do you like the idea of cash flowing in twice a week, or every 6 weeks?
For the sake of the skeptics, next time you do something like this, make sure you do the lean method first so that your task times improve more for the batch method. Heck, handicap yourself for the lean method; use one hand and your teeth or something. 18 seconds beats 3:47 like a rented mule.
Update: The Fashion-Incubator blog readers have also chimed in with some passionate feedback. Check it out.
Subscribe to LSS Academy