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By Root 3077 0

a new perspective on the two production methods that have defined this field in the last 100 years—the Henry Ford assembly line system and the Dr. Ohno TPS. Everyone knows that Henry Ford is the father of the modern assembly line mode of production, but most have focused on how this system enables better utilization of resources (material is brought to the worker) and it achieves the dream of balancing capacity. Goldratt took a different point of view. Henry Ford’s real objective was to improve the flow of products through his factory. He was so successful at improving flow that in 1926, the elapsed time between unloading iron ore from the boat to the same iron being loaded on a freight train as a finished automobile was an astonishingly fast 81 hours (Ford, 1928). The magnitude of this achievement is underscored by the fact that eight decades later, no automobile manufacturer can come close to Ford’s achievement. Contrary to the traditional belief that one cannot achieve maximum or full output without ensuring that all resources are productive and producing all of the time, Ford’s method produced far more output from the factory as a whole. In fact, a focus on flow can result in some resources running out of work occasionally. However, system Throughput is not compromised, but actually enhanced. The success of Henry Ford clearly demonstrated that the resource centric view had led to false assumptions, but this lesson was mostly lost in history from 1926 to the 1970s and the emergence of TPS.

Goldratt concludes that both Henry Ford’s assembly line and Taichi Ohno’s TPS were systems in which achieving smooth flow through production was a prime objective and that the generalized method they followed can be summarized by the following four principles:

1. Improving flow (or equivalently lead time) is a primary objective of operations.

2. This primary objective should be translated into a practical mechanism that guides the operation when not to produce (prevents overproduction).

3. Local efficiencies must be abolished.

4. A focused process to balance flow must be in place (Goldratt, 2009).

Of particular significance is the second statement. Goldratt points out that the assembly line and the Kanban system of Toyota are essentially systems that tell workstations when not to produce. For instance, in an assembly line if one workstation stops, all others have to stop because the line stops and there is no place to put material if any of the other stations continue to produce. Similarly, in a Kanban system when there are no Kanban cards, work centers stop working. In contrast, in most traditional production operations one of the key arguments for maintaining significant work-in-progress (WIP) queues is to decouple each work center from other work centers and their possible disruptions.

Henry Ford relied on space to limit production while Taichi Ohno developed the Kanban system3 to do the same. Of course, if we are introducing a system that intentionally stops resources from producing, then clearly Principle 3 (abolish local efficiencies) is unavoidable. What is interesting is that both Henry Ford and Taichi Ohno did not simply stop at limiting production, but leveraged these situations into opportunities for improving processes that streamlined and increased the volume of flow. When the built-in mechanisms—space or inventory—create a line stoppage, one has clear visibility about what caused the stoppage and, hence, points to the problem that needs to be solved to better balance the flow. The magnitude of improvements that both Ford and Toyota were able to achieve over their competitors in increased speed and reduced total cost stands as testimony to the effectiveness of their approaches.

In spite of the tremendous success of their methods and the volumes of articles and books written about their methods, the focus on flow did not spread to all parts of the manufacturing industry. In a small country like Japan, given the clear success of Toyota as a business and their attribution of this success to TPS, one would expect