I made a rather extensive Sunday brunch a while ago for the
family, with a couple of new recipes that I prepared the day before– sweet
rolls and a spinach and almond pie (think soufflé in a crust). Both turned out
great, but in my “retrospective” after spending the day cooking, I realized I
had missed something.
Both recipes had many steps, and since the rolls required
quite a bit of time in the bread machine, I made the assumption that I could
work on them concurrently (start the rolls in the bread machine, start the pie
crust, then the filling, etc.). I goofed.
While the time that I needed to prepare both items could be
handled by me, I failed to take into account that both items needed to end up
in the oven – at very different temperatures. I handled my WIP (work in progress) limit just
fine, but paid no attention to the oven’s WIP limit of ONE. Everything turned
out fine, but it meant that I had to delay baking the pie (the rolls took
priority, since they HAD to go in the oven once they had risen sufficiently).
My afternoon of baking ran well into the evening. Not that I was busy the whole
time. I just had to wait on the oven.
This story illustrates the reasons why lean processes seek to reduce the 3 M’s – muri (overburden), muda
(waste), and mura (unevenness). I
experienced mura, because I had to wait on the oven’s availability, then rush
to finish the job. The oven was dealing with muri, as it needed to respond to
multiple requests and couldn’t. And I experienced muda, as I wasted a beautiful
evening waiting on the oven, when I could’ve gone for a bike ride!
This is similar to situations in development, where the 10
developers on a team may not be paying attention to the overload of tasks
placed upon the 5 QA engineers; or where the 7 development teams aren’t aware
of all the tasks the app support team must do for each team. Unless everyone involved in the process is aware of
where the limits (sometimes called bottlenecks) exist, you may find yourself
with excess inventory (code waiting to be delivered, or a pie waiting to be
baked). The 3 M’s seem to go together - unevenness in the process is a symptom
of overburden on one part of the process, and both result in waste, as sections
need to wait, and inventory ages.
What can be done to alleviate bottlenecks, or limits?
Sometimes, re-allocating staff can help, but only briefly – this isn’t a
permanent solution. When you’ve got one thing (like an oven), that just has one
task (bake things), the upstream process needs to take that limit into account.
When my husband offered to help, there really was nothing he could do, but wait
with me. Now, if he could buy me a second oven…
