The Reality of Lean Manufacturing

By: David Meier

When discussing lean implementations there is always a conversation about whether some (or all) of the principals make sense. In reality very few of the principals will make sense to our rational mind for one reason: properly applied, lean manufacturing will create urgency, stress, and discomfort. Our normal human tendency is to seek comfort and calm. These represent safety and security. Urgency, stress and discomfort represent danger and invoke our "fight or flight" mechanism of survival. The problem is that we do not understand the fundamental philosophy (thinking) of lean.

During a review of one facility an engineer proudly stated that he had "eliminated the machine downtime". This was exciting news as the reliability of the equipment had caused many problems in meeting the production schedule. When asked how the problem was corrected his answer indicated a very common misconception regarding the core philosophies of lean. He replied that he had installed a large in-process buffer after the troublesome machine so that the NEXT process would not incur any downtime.

There are really two misunderstandings in this case. First of all the addition of buffers obviously adds inventory and cost (waste), as well as the variety of problems associated with buffers (increased potential for defects, reduced flexibility to changing demands etc.). More importantly is that the use of buffers opposes the concept of the customer directly signaling the need to produce. The direct connection with the customer process is lost. Buffers by nature encourage "push" thinking. The buffer must be kept full at all times regardless of what the customer process actually needs. The basis for single piece flow is to minimize waste by directly responding to immediate customer requirements.

Responding to immediate customer needs via single piece flow will create urgency, stress, and discomfort if the system is not reliable. This points out the second misunderstanding. Perhaps one of the most avoided aspects of lean is that if properly applied lean will drive urgency to actually correct problems rather than cover them. At Toyota buffers and excess inventory are seen as indicators of weakness in the system. Challenges to reduce or eliminate inventory are issued and diligent efforts are made to strengthen the system and improve reliability.

The true benefit then of implementing lean is the overall strengthening of the system. If applied properly the lean methods will make any shortcomings in the system appear quickly, and the shortcomings will have profound impacts. If operations are closely linked utilizing single piece flow and one of the operations fails, how long will it take before all operations are also stopped? Not very long! This will cause the problem to gain immediate attention, and a high level of importance will be placed on correcting the problem and installing permanent preventive measures.

This is an example of the saying "the squeaky wheel gets the grease". In a lean system the idea is for the squeak (the problem needing attention) to be heard as early as possible, and for it to be so loud and obnoxious that grease is quickly applied. To take it a step further we find the root cause of the squeak and prevent the recurrence.

Indications of the success of a lean implementation are:

  • Problems will surface quickly and obviously (at times painfully).
  • A sense of urgency will automatically be created regarding system reliability.
  • The weakest point of the system will be stressed and broken.
  • Operations will be forced to be close to the edge and as tight as possible.
  • Consistent application in all areas and in the thinking and development of our practices.

Simply stated an objective of a lean system is to FORCE the need for waste elimination and continuous improvement. The challenge is to resist our normal human instinct to seek comfort rather that discomfort and the stress of a lean system can be very uncomfortable if it is not reliable. The key is to continually push beyond the "comfort zone" (the sensible level) and drive continuous improvement to develop and strengthen system reliability. The benefits of lean are great, but they come at a price, and the price is hard work and dedicated determination.

David Meier, Senior Lean Manufacturing Consultant, Total Systems Development, can be reach at davidmeier@mindspring.com or 1-800-254-4023.