3. Is there a difference between TPS and Lean?

I’d like to say that there isn’t. At least there was not suppose to be when the term “Lean” got coined and various parties started trying to codify some of the knowledge. But if you look at what passes for Lean today versus what Toyota calls its production system there are some pretty important differences. I don’t think that any of this has been intentional it is just the way things have developed in the U.S. and other parts of the world. I will list a couple of the chief differences. First off the Lean movement seems disturbingly preoccupied by the abstract notion of achieving “flow” in all aspects of business. While this is a nice analogy for having smooth running operations it is not a quantifiable goal or even an economic one in many cases. In actual TPS the concept of “flow” is just listed as one of four elements of a Just in Time System (flow, takt time, pull, and level production). And JIT is just one part of the still larger overall system. This preoccupation with flow is why several Toyota executives including the former President Mr. Cho have commented that people in the U.S. seem preoccupied with merely the logistical aspects of TPS. The emphasis on quality, equipment availability, product development, supplier development, and people development is sadly lacking.

Second the lean movement is characterized by its zealousness in drawing Value Stream Maps in order to identify waste and drive improves in any system. There is nothing inherently wrong with drawing these maps. The maps are an excellent 10,000 foot level tool to look and see what is going on in your facility from raw material to finished goods and highlight certain wastes. The problem is that practitioners seem to think that this is the only way to do lean and that the tool will show all problems in production. Unfortunately the tool was never intended within Toyota to do all this. The original English name for the tool was Material and Information Flow Analysis and it was developed by consultants in Toyota for working with suppliers mainly and not internal parts of Toyota. The tool shows the overall lead-time from the stage of raw material at the supplier and into the supplier parts area for Toyota’s final assembly shops. Used correctly it can help show disruptions in flow, levels of inventory, delays in conveyance, problems in scheduling and other matters pertaining to elements of Just in Time production. The tool is not designed for and does a poor job of highlighting issues let alone root causes of quality problems, equipment availability, tooling, human resources, or other key items. As the former head of the Toyota Supplier Support Center Hajime Ohba has remarked on more than on occasion all the emphasis on drawing maps in the U.S. is missing the point and becoming an immense waste itself in many cases.

The third key difference that I will mention is the core belief in the lean movement that you just have to apply the tools of lean and you will get results and thus somehow magically create a system in the process. In other words you must draw value stream maps, you must have a supermarket and kanban, you must have U-shaped cells, and you must have standardized work charts posted on all machines, etc. Unfortunately this is putting the cart before the horse and actually causing problems in quite a few companies that I visit. What is important in TPS is adhering to principles (building in quality, balancing work to customer demand, avoiding overproduction, etc.) and achieving results. Emphasis in Toyota is mainly put on recognizing problem situations and resolving the issue right away in TPS. I have no doubt that lean practitioners want to solve problems as well but when the emphasis starts first on applying the tool without solving the problem then there is conflict and often a waste of time despite the best of intentions.