POUS and Water Spiders -
Key Elements in One Piece Flow
The Ideal Process
One Piece Flow is the optimal manufacturing process. All the resources get aligned and the product literally flows in a stream towards the shipping dock. Not always and not all products can be manufactured with this system, but the closer we can get to it, the better the business will run.
Change of mind-set, and willingness to continuously improve are all that this system requires.
In order to achieve this smooth process (NUMMI-like), the old concept of a central warehouse needs to be changed. From now on we should operate like a supermarket. The supplies must arrive to the closest possible point of use, so there is no excessive movement-transportation of the parts by the manufacturing operators. In some cases the materials will be delivered directly by an external supplier, in some other cases an internal supplier will do the function of "water-spider" constantly replenishing materials exactly where they are needed, when they are needed and in the amounts required for a short period of operation. Some of these replenishments of supplies take place each hour or even fewer than 60 minutes.
The role of the Water Spider is a key element in this process. It is Not an Entry Level position. Water Spiders need to be familiar with the needs of each workstation and the process in general. An authentic Leadership attitude is required to sense the delicate mission and a feel for the intricacies of each process will really help big time. This is only achieved with continuously improved Communication - yes Communication Again!
When the gurus from Toyota observed the operation of a Safeway supermarket in New York, they discovered the power of this process that they have called "pull" since it is the "pull" of parts from the bin that will trigger the new supply. Just as consumers in the supermarket pull from the shelves the products they want to buy and a supplier replenishes in the appropriate amounts for the next day or few hours. It woks like a clock!
The opposite of this is the traditional "push" when you get more than you need, and sometimes causes waste of space and uncomfortable conditions.
Of course there is much more to One Piece Flow achievement, however, POUS is a critical piece of it. To support this concept, almost everywhere is applicable the use of "Kambans" or Signals that help suppliers see the level of product. Tilted bins that can be fed from the back while operators pull pieces from the front are also a great help in this conversion. A two-bin system can also be used, when one bin is empty the operator sends it to the back and that is the Kamban for the supplier.