In Chapter 4 we discussed in some detail the concept of pull zones. Now that we've gone through the four drivers you may better appreciate how essential it is that you establish these zones. It has been utterly amazing to me how many efforts in applying pull zones (or supermarkets) falter and then fail and how many consultants and plants pursuing globally competitive manufacturing simply choose to ignore this most important step. You must implement these zones at the outset of your change effort (pull zone is a tool in both WPO and U-flow) or most likely all your efforts will come tumbling down like a house of cards.

First, it is important to remember that pull zones are not meant to be some long-term initiative, though they are often required for some time. Essentially they begin the process of eliminating all centralized stores areas in the factory and they end when the factory has progressed to a point that material is brought in the smallest quantities possible directly to the point of use without intermediate storage of any kind required.

But achieving this often requires a considerable amount of time and effort and usually is not fully accomplished until a factory has achieved at least a Level III in WFM. Therefore, pull zones become a necessity for a factory trying to move from a conventional mode of operation to waste free. There are a number of ways to set up pull zones but...