It has to do with supermarkets. Not the kind where you buy groceries, but lean supermarkets where raw materials for manufacturing cells are stored and replenished. I've always treated this concept very casually, as if it's a no-brainer and not something requiring sound execution of fundamentals. But in fact there are 3 key requirements for a lean supermarket:
- Addressing: Every physical location in the supermarket must have a unique address. This might seem trivial or obvious, but a rack with a row of part numbered bins does not meet this requirement. And there are many situations where this is a challenge, as in a refrigerator for example. But management of raw materials, both use and replenishment, rely heavily on this element.
- FIFO: First in, first out. Again this may seem obvious, but all too often we rely on people checking expiration dates and hoping that newer material doesn't get stacked or poured onto older material in a bin. The supermarket must facilitate the proper movement of material. Flow racks help a lot, but there are certain situations where this can become more difficult, as in a refrigerator for example.
- Quantities on the Bin: Inventory management depends entirely on making sure that the quantities you think you have are really the quantities that you have. And that replenishment takes place at the proper time and in the proper quantity. This may be easy with relatively small quantities of relatively small parts that fit neatly in a 2-bin system, but more exotic storage conditions (like a fridge) make it harder to do. We often take some liberties with how we "define a bin" that tax our ability to easily label it. But failing to do so will eventually and certainly lead to a break down.