I really enjoyed writing this chapter! My goal was to illustrate the extent to which things can look radically different and yet share the same underlying principles and philosophy. The excerpt below comes after a description of a production line at Toyota; the “TPS” of the chapter title is the Toyota Production System.
Beyond the already-familiar “Kanban“, a number of Japanese terms are introduced. I use them freely in this chapter but rarely elsewhere (and I explain why).
This [preceding] description is rather simplistic, but there’s enough here for some striking characteristics of the system to be noted:
- All three tools (kanban, heijunka, and andon) are examples of visual management.
- Inventory of all kinds is limited. Neither basic supplies nor WIP (the subassemblies, or partially-built products) will be replenished until equivalent amounts have been pulled from downstream.
- Even though, perhaps, it might seem more efficient to do so, the production line doesn’t work in large batches of similar items. Instead, it produces a variety of products spread over the course of the day.
- Workers on the production line would rather stop the line (for everyone) than allow work of inferior quality to proceed.
- This system and the kanban boards from Part I work very differently. On the production line, the kanban [1] are sent upstream to signal that there is demand to be fulfilled. On our boards, the cards represent work items as they flow downstream; signals are implied by the gaps between the actual amount of work in progress in each state and the corresponding WIP limits.
- The heijunka box and our kanban boards both allow the mix of work to be managed.
It seems perverse, not only setting things up to work in this deliberately difficult and seemingly inefficient manner, but empowering workers to bring it all to a halt at any time! Clearly there must something special about the company’s culture for this to work at all, but why would they choose to do things this way?
TPS and Lean in Perspective
To answer that question you must understand TPS as a magnificent example of systems thinking.
It starts with a vision, a true north that gives the direction for change:
- Single-piece flow, in sequence, on demand, with zero defects; 100% value-adding activities and security for the people performing them
The technology does not yet exist to make it economical to run the entire production line in batches of one (which is what single-piece flow means), but the pursuit of this perhaps impossible vision is what propelled Toyota from its struggles in postwar Japan—where land, factory space, plant, and materials were all in short supply—to the global market leadership position that it now occupies.
The tools support one or both of two purposes:
- Satisfying customer demand as quickly and as smoothly as (currently) possible with the minimum amount of inventory
- Evolving the company to take it closer to its vision, harnessing the abilities of its entire workforce to smooth flow, reduce inventories, prevent defects, eliminate other forms of waste, and (not least) design new products that customers really want and that can be produced both profitably and sustainably
The two pillars of just-in-time and respect for people are shorthand for those sub-goals.
Often missed is this crucial point: The pillars and the tools can been seen in their proper perspective only once it is grasped that Toyota’s pursuit of perfection is a multi-generational challenge. Toyota works not only to build cars, but also to build the company capable of delivering on its vision.
Divorced from that kind of thinking, the tools of Lean can seem shallow. Without the tools, it can be even worse—too often we hear Lean reduced simply to a short-term focus on waste (perhaps to dress up exercises in cost cutting), or to continuous improvement (important, but very hard to sustain in isolation). The challenge of the Lean movement is to make sure that the thinking is packaged up with the tools so that people can apply them appropriately in context.
[1] “Kanban are like sheep” – One kanban, two kanban, …
