Up to now, we really have only seen one example of a lean process, optimizing the daily chore of unloading the dishwasher. What might have seemed like a random exploration, actually follows a proven five step process. Also known as the “five principles of lean manufacturing”, these have been defined by Womack and Jones in their book “The machine that changed the world“. Nowadays, these five principles are not only applied in manufacturing, but are well known management techniques to improve workplace efficiency. They are:
- Define Value
- Map the value stream
- Create flow
- Use a pull system
- Pursue perfection
These might sound pretty abstract, unless you have a “genba” (the Japanese word for “crime scene”) like your kitchen or manufacturing floor in mind. The five principles of lean are often depicted on a circle, as true optimality cannot be achieved in practice and most improvements let you discover additional opportunities.
Define Value is much more difficult than it sounds, and often changes during the process or as your business evolves. When we started to think about how to unload the dishwasher as fast as possible, we quickly realized that we don’t want to put too much strain on people and excluded them to simply move faster very early on. We have also realized that we don’t want to give up the cultural values of maintaining a diverse inventory of dishes and tools. Once we optimized the process around these constraints, we found that storing items in shelves can be mostly eliminated by mixing clean and dirty dishes at the expense of additional water and energy usage. These are all the same problems a business has. We need to increase throughput, minimize cost, protect workers and the environment and so on. It is very difficult to keep all of these in mind at once and they change more often than not.
Map the value stream is to identify what the activities are that are creating customer value. In the dishwasher example, these were taking things out and putting them away. Moving them across the house is an activity that does not directly create value, but is so-called “waste”. The goal is to reduce waste as much as possible. Digging deeper, “taking things out” is also a sequence of actions considering of value-adding and necessary activities, each with their associated wastes such as motion, defects, etc. Clearly, there are wastes that stand out right away, whereas others take time to get discovered. What exactly the different kinds of waste are is introduced in the next lesson “The seven deadly wastes“.
Create flow emphasizes the idea that any stand-still is waste. Instead, a process needs to keep moving, preferably exclusively relying on activities that actually add value. Waiting for something is the most obvious source of waste that stands in the way of “flow”. Often, tasks can be rearranged, work loads across stations can be balanced, and employees can be trained to be multi-skilled and adaptive to jump in where they are needed to keep things flowing. Having “flow” does not mean that we are done, however. This can be easily seen in the dishwasher example, where “flow” might mean quickly moving single items between the dishwasher and stations, an activity that looks “busy”, but is very wasteful.
Establish pull is the idea to trigger processes based on customer input, for example an order. In the dishwasher example, we found that starting to use items from the clean dishwasher can reduce overproduction. We only unload the dishwasher once we start to run out of clean dishes. This is an example of a “pull system”. Another household example is to put cards at the location of a consumable to trigger reordering. Pull therefore helps to reduce inventory and work-in-process, while adding information to the system. An efficient way to manage pull in a manufacturing system is to use so-called “Kanban” cards. We will pick-up on “pull” and “Kanban” in the second part of this course “Lean in the line“.
Pursue perfection requires to continuously re-evaluate a running system. In Japan, this is done during so called “genba walks” where workers and management look out for waste. While you might be able to detect waste on your way to the water fountain, genba walks should also involve a discussion on whether the current process still meets customer and business needs, or whether the performance metrics that you aim for have changed.