This lesson introduces the basics of “lean” thinking. What “lean” is, is difficult to define. In a nutshell, “lean” refers to a mental framework that not only help you to do more with less, but also helps you to evaluate what “more” and “less” mean. As this definition is pretty fuzzy, it is difficult to learn lean thinking from a book. Instead, lean is best experienced at what the Japanese refer to as “genba”, literally “the actual place”, or the “crime scene”. This does not mean that you cannot experience and learn “lean” by immersing into a good narrative or by putting theory into practice at home. In fact, the most successful books on lean of all time come in the form of “business novels”, which might really be the only way to appreciate the holistic aspects of the lean mindset. In this spirit, this lesson uses a daily chore, unloading your dishwasher, as a motivating example to prepare you for “the five steps to lean” and “the seven deadly wastes“, both core-concepts of lean organization.
What is your goal?
What it is that makes unloading the dishwasher so annoying? Is it that putting dirty dishes away and starting the machine is simply more rewarding? Do we know that we are trapped in a highly inefficient process, akin biking uphill on a slight incline, just steep enough to slow us down and never get us “flow”? Or, does the task always happen at the wrong time when the rest of the family has already moved on to the next fun activity?
As we cannot really pinpoint what it is that makes unloading the dishwasher so unrewarding, let’s focus on getting it done as quickly as possible. Time is easy to measure using a stopwatch. How can we go about decreasing time then? Is it to try to move as quickly as possible, risking that we are completely exhausted and dishes break every now and then? We are rather interested in simple changes that do not lead to increased tear and wear on both dishes and people, but being able to do more with less.
Map out the value chain
Let’s look at what emptying the dishwasher actually entails. The first is taking items out. Second, items need to be moved to their storage locations. Third, we need to place items in cupboards and shelves. What is the first thing that we can optimize here? This leads us to our first improvement: Storage locations should be as close to the dishwasher as possible.
For example, left or right above the dishwasher for light dishes and left or right next to the dishwasher for heavy pots minimizes not only transport, but also motion. Optimally, one would elevate the dishwasher just enough that bending motions are reduced. All of this is often not possible in most kitchens, and most adventures into “lean” often end when the obvious improvements are not applicable. Fortunately, the dishwasher problem – as most trivial looking problems in manufacturing – is surprisingly deep.
Also, giving up now is actually fatal. Not having access to an optimal storage location is already a problem. Even more effort should therefore be put into optimizing your second choices. Most people don’t do this, however, as they are frustrated by not being able to do the obvious and underestimate the big impact that the sum of small changes can have in the long run.
The next question you should ask yourself is whether you can get away with a more compact assortment of dishes and cutlery that can indeed be stored in a more optimal location. While the answer here is “no” for most people, and there indeed is an occasional need for even the fanciest sauciere, this leads to a consideration of frequency of use. With this, we can derive our second improvement: Frequently used items should be stored in the closest location, those less often used should be stored in the furthest available location.
This is probably already the case for most people and if it is not, this has probably been one of the most useful articles you have read in a year. But there is more we can do.
Now that we have minimized transport that is required to solve the problem by optimally assigning item groups to a set of locations (a computationally hard optimization problem known as the “quadratic assignment” problem), it is worthwhile to take a closer look at what actually happens during the remaining transport.
Our first realization is that we would want to carry as much as possible everytime we go. This becomes pretty clear when imaging that walking back and forth between the drawer and the dishwasher for every single spoon will take much longer than moving the cutlery by the handful. This directly informs how we carry out the emptying task – we should try to grab as much items as we can before going anywhere. This leads to a third suggested improvement: Many more items can be carried when stacking them, we should therefore focussing on unloading items in groups of identical objects.
It turns out that some items stack better than others. For example, one can easily grab 10-15 spoons in a single hand or stack 10 or so dishes, but I have a much harder time with glasses, moving only two in each hand. Glasses also don’t stack well with mugs, which don’t fit with wine glasses and so on. This introduces a second “frequency” in our consideration. Some groups of items, such as dishes, can be moved during one or two trips, whereas glasses and mugs require many trips. This can be condensed into a fourth piece of advice: Groups of items that require many trips from dishwasher to storage location should be closer than groups of items that can be stored in fewer trips.
Now that we better understand how to speed up the unloading process, we might also want to think about how to load the dishwasher. In an ideal scenario with storage to the left and the right of the machine, we should load items accordingly. As we want to grab as many items as possible and stack them, items should also be loaded this way. This can usually be achieved without any additional cost, but pays off downstream.
Has everything been said about the dishwasher unloading problem? Far from it.
For example, now that you have minimized transportation, it might make sense to think about moving item groups on a tray. This bears the question whether reduced round trip time justifies the additional manipulation (placing and picking from the tray). This problem can probably only be solved using a stopwatch. It is also interesting whether transport could be completely reduced by working with a partner who is strategically placed and to whom you can hand over items. Whether this approach is more than double as fast as when you do it alone (super-linear!) will depend on whether you can balance your line, that is reduce waiting for either you and your partner while one is storing or retrieving an item. Also, now that every second counts, opening and closing cupboards and drawers becomes a nuisance. While good organization and planning can help to open and close each cupboard only exactly once, some might start thinking about structural changes and remove unnecessary doors.
Lean makes it easy to get carried away in details, however. There are two very big no-nos that would trip off even the leanest approach. First, not everything in the dishwasher might actually need washing, but instead could have been stored right away or after a quick wipe-off. But what is really the dumbest thing one could do? Putting dishes away right before setting the table. Therefore, always grab dishes from the clean dishwasher and only start it once you start running out on critical items.
So what about all the dishes waiting in the sink? An obvious solution would be to replace one of your cabinets with a second dishwasher. This dishwasher would then serve as a “buffer”, while you are living out the “clean” dishwasher, and will need to be started once you begin running out of necessary items – a triggering event known as “pull” in lean organization. This might also require starting to fill the “clean” one with dirty dishes before it is empty, which is not very ecological. This brings us back to our first question: what is your goal?
You should now have a pretty good idea about a typical lean optimization task looks like. What looks like a simple task with little room to improve actually has tremendous optimization potential, depending on what your goals and constraints are. Surprisingly, new ways of doing things also shed light on new potential targets and constraints, making your journey to lean a never-ending process. The “five steps to lean” that you have just went through are explained in more detail in the next lesson.
The main reason is that what initially appears as a collection of rules turns out to be a set of contradictions. Toyota has understood that and describes it with the “true north” analogy. A compass needle gives you very good directions to the North pole until you get actually close. Then, the compass needle will point you to the magnetic north pole (which is not quite where the geographic pole is) and eventually let you turn in circles. Analogous, the closer you approach optimality, the less you can rely on simple rules of thumb.