Hurry Up and Wait! – Muri

[tweetmeme source="leanisgood" service="ow.ly"]Hurry up and wait.”  That was our saying way back when I was a young, and spritely United States Marine.  Our standard practice was to arrive for everything really early then wait for something to happen, the Air Force people to let us board a plane, the Navy people to stick needles in us — the intent was to never be late, get done whatever we needed to get done, and move on (the hard part was occupying your Marines while they waited – they tend to be creative and biased towards action – if you don’t keep them busy they will either damage important government property or hurt each other, both of those things are the same in the eyes of the government.)  Anyway, that isn’t the problem in manufacturing.

In manufacturing we sometimes hurry up to get the most out of our ‘capacity’, but what we end up doing is waiting.  This is because of the something called muri.  Muri is one of the 3 wasteful M’s in lean, the others being mura and muda.   I don’t speak Japanese but my understanding is that muri roughly mean overburdening, it can also mean unreasonableness and absurdity.

Historically of the things that businesses have tried to do is trim capacity to demand.  No sense in paying for a bunch of capacity that we don’t need was the rationale.  What optimizing these utilization based metrics really did was drive up lead times.  If you drive up lead times you will need to carry larger inventory, since you are going to carry lots of inventory might as well do long production runs.  That sounds pretty good running at very high levels of utilization leads to longer lead times.

Click to enlarge

Increasing the capacity utilization of a systems tends to increase the lead times of the system.  It will take longer to get parts through the system.  I will leave you to comment about the ‘whys’ for this increase in lead time as capacity utilization increases for now and will stick to describing some of the implications:

  1. Implications on equipment. Running equipment at its physical limit for speed means that every lost minute of downtime (doesn’t matter why it stopped – breakdown, process problem, stick out) is gone forever.  If your machinery is running less than its maximum speed you have some ‘protective capacity’ left to catch up if necessary.  You can add some people if necessary – they’re flexible like that if you have trained them.
  2. Implications on people. Bryan mentioned in a post a few weeks ago about what happens when people have too much assigned to them.  They don’t get anything done – nothing timely anyway.  This leads to a lot of frustration because people don’t have an opportunity to do a good job and that conflicts with their self-esteem (think about Deming’s point #12).  In the Corps people were generally given two maybe three things to do (actually purposes to accomplish not things really), but not five or six.  I was in a blitz a couple weeks ago and watch some people deal with a chronic process problem that lead to either defective product or customer dissatisfaction.  They asked why a lot and came up with ‘operator doesn’t have time to perform all tasks’ as  one of their root causes.  They eliminated some of the waste in the process: by moving stuff around mostly – could be categorized as 5S, by making the work simpler through visuality and a couple physical contact poka yokes.  That’s all good stuff but then they went farther.   They still weren’t happy with how much a certain operator in the process had assigned to her.  The stopwatches said it “should” be possible for the operator to get everything done right in the right amount of time (I like to call this “shoulding on people”).  They weren’t happy with that.  They moved a little work from this operator to a less burdened one.  The operators in question did this themselves even the person with the ‘new’ responsibilities.
  3. You can push that drastic up turn of the Muri curve to the right by increasing stability. I am not sure if this is an implication or something else but it is worth mentioning.  The more stable your process is the less your lead time will increase with burden – or at least the elasticity of the curve won’t increase until you get into higher levels of utilization.  We want to push that part of the curve where my calculus professor from college would say “it begins to really hold beer”, meaning that it begins to increase at an increasing rate out to the right.

Don’t forget to look for muri when you are looking for muda.  You might as well look for mura or unevenness or inconsistency while you are watching.  Maybe I’ll talk about mura and how it changes the muri curve later.

Do you agree that lead time increases with overburden?  If so, why do you think it does?  Is this often overlooked while we are searching for muda?  I’d like to hear your thoughts on this.

Bruce

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2 Responses

  1. […] Read Posts Hurry Up and Wait! – MuriThe Great Jackass Fallacy – Dan Pink and W. Edwards DemingIt's All About the Why, the Other […]

  2. […] would overburden the organization’s problem solvers.  This would be a form of dreaded muri right?  I’ve read and heard much about the Toyota staffing levels required to operate TPS […]

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