“Flow.” This is not just a word but a fundamental concept that underpins business. Material flows, information flows, money flows, and time flows. Understanding and managing these flows is crucial for the success of any business.
There are several conditions in which we talk about flow.
1️⃣ Dakuryu【濁流】 and Seiryu【清流】
Dakuryu is translated as “muddy stream.” Daku【濁】means to become turbid or impure. The symbol Daku【濁】 consisted of 【氵】, which represents water, and 【蜀】, which represents ugly-looking insects swarming on a tree. This symbol contains such discomfort.
On the other hand, Seiryu【清流】 is translated as a clear stream. The symbol, Sei 【清】, has blue【青】on the right side. “Blue water” is clean and pure. This symbol is also used for 5S, Seiketsu【清潔】 and Seisou 【清掃】.
These two words have been used frequently outside of water flow. For example, during the Hun Dynasty, the corrupted bureaucrats were called Dakuryu, and the reformists were called the Seiryu.
In operations, we use these words to describe flow with defects. Defects are contaminations in the flow, which we must eliminate. Taiichi Ohno has stated the six rules of Kanban, one of which is to keep the quality at 100%. If not, the flow will be contaminated. We must identify the source of contamination and bring it back to the pure flow. At the same time, we should design the material flow based on Seiryu with zero defect conditions. When a defect is made, it immediately impacts the flow and highlights the problem. From such thinking on quality, we started to say Genryu Kanri 【源流管理】, which means “headwater control” or “source control” of quality.
This comparison between Dakuryu and Seiryu should be considered more than material and quality issues. Another typical example is information. What are the accurate customer orders, and who is changing or “contaminating” those? There are many situations in which different parties add volume during the planning process. When the real operations time came, the actual demand was significantly lower than what they invested for. And then, the high fixed cost is blamed on the operations. However, the critical question is, who contaminated the information? It is not the operations. It was those in the planning stages. At the same time, I am not saying that we shouldn’t “contaminate.” This is a business decision, and the senior manager should know about this. Unfortunately, it is hidden, and most don’t know who hid what, leading to a high-cost structure.
2️⃣ Ranryu【乱流】 and Seiryu【整流】
Ranryu【乱流】 is translated as “turbulence.” Ran【乱】means disorder, confusion, or disarray. This is also used as “war,” which is typically used as a rebellion that failed. This rebellion includes using force, which could lead to political power change.
Seiryu【整流】 is the opposite. It is the transition of rectification. It means changing the turbulence to organize a one-directional flow. Sei【整】 means to organize. It is used for other 5S words, Seiri【整理】 and Seiton【整頓】.
Ranryu is a condition inside operations where volume fluctuates—many divisions and confluence points exist. The pace of flow is random. The layout sequence does not match the work sequence. There is lots of transportation. There are a bunch of stockouts, but at the same time, there is a high inventory level.
Of course, this could happen in the information flow. Or maybe we should not call it a flow—a mess. Because of that, we see many meetings with many people attending, yet there is no outcome—a sign of information turbulence.
3️⃣ Konryu【混流】
Konryu【混流】 is “mixed flow.” And inside the “mixed flow,” we can have Dakuryu【濁流】 & Seiryu【清流】, Ranryu【乱流】 and Seiryu【整流】. Dakuryu in a mixed flow is somewhat easy to understand; it is a mixed flow with defects. Ranryu needs more careful attention. One way to distinguish is the Heijyunka. Mixed flow without Heijyunka is Ranryu. The products are mixed, but there are no rules for mixing. Even if there is a rule for mixing, if that is not visible on the Genba, it is Ranryu. What is dangerous about the mixed flow, Ranryu, is that you will have many fluctuations in each SKU on top of the total volume fluctuations. This is when we have situations of high inventory but many shortages. To prevent this, we must start implementing some level of Heijyunka. And then, we need a mechanism to highlight those on Genba. Providing the information individually is ideal so people won't be tempted to change the sequence.
4️⃣ Flow and 5S
As I summarized the flow conditions, I recognized that we use many symbols in the 5S.
Unfortunately, many 5S activities are separated from “flow.” The typical 5S does not consider flow; it is static. The location of the material is determined without considering how the material should get there. Information is provided in an area where the worker needs to move around. There is a crisscross of materials and human flow. The 5S that does not consider flow is not sustainable or requires much effort to sustain. Instead, we should think of 5S as the shadow of flow. 5S should be designed based on Seiryu【清流】 and Seiryu【整流】.
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