The Toyota Production System, or what we call sometimes call Lean management, is simply the practice of planning, trying out your plan, reflecting (hansei) on what worked and what did not work and making adjustments through problem solving.
Everyday skills in practical problem solving are required for Lean management to work because there will be problems every day. No plan goes according to plan, and what we don’t know is always greater than what we know. In addition, for a Lean system to work, problems must be exposed and swiftly addressed.
However, traditional management behavior can reward hiding or smothering problems by adding more resources. Can you see the problem in this process? No? Operation #5 (fifth paper clip from left, below) is an incapable process.
In the process below, it is business as usual, and traditional management gets through it by using scientifically determined buffers, expediting, throwing more money at it, or all of the above. These are expensive solutions that do not address the problem.
Perhaps experienced manufacturing managers with decades of MRP-push management experience can get through this with no problem. But “no problem” is a problem. It is either an indication of satisfaction with the status quo or a lack of awareness of what an ideal condition looks like.
Invisible problems are worse than visible problems because you cannot eliminate invisible problems, except by chance. Here we know we have a problem, but it is not possible to grasp the situation fully and accurately. We need to start at the point of problem detection and work upstream.
We need to pull to find the point of cause. In this case there is a bottleneck at operation #4 (fourth paper clip from left). When you attempt to pull, the problem becomes visible. Now we can isolate and eliminate the problem. It’s even OK to buffer around this problem – just don’t push.
Overproduction, inventory and various “just in case” hedges all covers up problems. Hiding problems undermines the Lean management system. That is why we pull.
Most elements of the Toyota Production System, sometimes called Lean tools, have the dual function of improving safety, quality, delivery and cost as well as making problems visible. This is true of 5S, kanban, just in time (takt, one piece flow, pull), standardized work, jidoka, and TPM. If everything is going so smoothly with your Lean implementation that you are not seeing problems, you have a problem.