Flow operations

Flow works or operations—the core principle of Just In Time.

The root of “flow operations” is Ford’s conveyor assembly line, which is undisputed. Toyota learned from Ford about the use of conveyor lines. However, the conveyor line spread to Germany, and the concept of “Fliessarbeit” or “Fliessende Arbeit” emerged. The idea is that by connecting the workstations and not using the conveyor, we can create a smooth flow works without stagnation. In 1930, this concept was introduced and translated as "Nagare" (流れ; Flow) and "Sagyou" (作業; Work or Operation) to Japan.

In 1938, when Toyota opened its first plant, Kiichiro Toyoda introduced “Just In Time.” Here, he provided training on flow work. According to Eiji Toyoda, the brochure for this training was about 10 cm thick. He conducted the training for the managers. We don’t know exactly what he wrote in that brochure. However, by the time he conducted such training, there was only one book titled “Flow Work,” written by Kyuzo Suzuki in 1930. After this book was published, we suddenly saw the term 'flow work' appearing in many Japanese documents.

Kyuzo Suzuki wrote that he referenced seven books from Germany.

Reuter, Handbuch der Rationalisierung. 1930.

Mackbach u. Kienzle, Fliessarbeit. 1926.

Lauke, Die Leistungsabstimmung bei Fliessarbeit. 1928.

Lang u. Hellpach, Die Gruppenfabrikation. 1922.

Ermanski, Theorie u. Praxis der Rationalisierung. 1928.

Dunn. Labor and Auttomobiles. 1929.

Roy, La formule allemande de Production nationalle dans l’industrie, 1929.

I don’t know how to type German, so there are mistakes. Still, it’s clear that many contributions to this topic came from Germany. However, my post is based on Suzuki’s 1930 book.

1️⃣ Categories

In his book, Suzuki discussed three types of production systems.

By work production (Job shop)

By group production

Flow work

Conveyor

No-conveyor

The interesting concept is this: “By group production.” “Gruppenfabrikation.” Here, this group is formed by a component. Processes needed for components are grouped to create a flow. However, this is not one-piece flow. Each group can have a different batch size. According to Suzuki, Daimler’s machine shops were organized in this way.

2️⃣ Rhythm

Suzuki explains that the core of Flow work is that it moves in rhythm. He introduced the equation for “rhythm,” which is t = 60/n, where n represents the required hourly volume. Although the equation resembles takt time calculations, he offers a more detailed and different explanation. “If the rhythm is too slow, increase sales, or abandon the product, or mix with a high-volume product.” Here, he suggests that t = 3 minutes is too slow. By the way, he refers to this t as “Albeit Takt.”

3️⃣ When the process doesn’t fit the rhythm

Not all processes will fit within this rhythm. In such cases, Suzuki suggests dividing, paralleling, or combining processes to improve efficiency. While this may make sense, it does not align with the flow from the TPS perspective. When we have parallel processes, there are split and merge points that alter the takt time.

Additionally, the book describes many unusual scenarios. For example, Suzuki suggests increasing the flow by 10% in the afternoon. In other words, Suzuki proposes that the rhythm should change based on the time of day, which could be pretty complicated.

Suzuki's writing differs greatly from what TPS states. Since it was written nearly 100 years ago, it includes many odd descriptions. But don’t we see similar mistakes today?

“Conveyor” does not mean “Flow Works or operations.” A conveyor might be used for transportation or storage, but it does not add value as products are in motion. In those cases, this is not a flow work.

“By group production,” and as we draw this group as a “box,” we assume that work flows inside the box. But inside a box, there is chaos.

Within a flow, you suddenly mix parallel processes, or a single-piece flow becomes a two-piece, three-piece, or other quantity process. We often overlook this and pretend that everything is flowing smoothly.

On the other hand, a concept never moves in one piece or in a constant flow. It is interesting to trace the source and see how things have evolved.

Reference

鈴木久蔵. (1930). 産業合理化講座 第5巻 (流れ作業). 日東社.