OVERVIEW

The Lean manufacturing methodologies separate product into two components: its labor or work content and the component parts. Lean manufacturers seek to achieve balance with the work content and physically link the manufacturing processes together so that the output of one process is directly consumed into the next downstream process. Resources are then staffed to match the daily customer requirements so that demand is met without the accumulation of finished goods inventories.

Work content represents only half of what is necessary to produce any product. Component parts are also required for the manufacture of a product. The Lean manufacturing methodologies recommend using a kanban material-handling strategy to make necessary components available to the manufacturing processes.

The most common usage of kanban is the "two-bin" material-handling system. Two-bin systems have been around for a long time. Lean manufacturing did not invent the two-bin system. Their use is not a new invention. However, as with many manual noncomputerized systems, they fell out of favor with the advent of modern MRP systems. Japanese manufacturers can be credited with resurrecting and improving upon the earlier two-bin systems by putting them to work in their post World War II noncomputerized manufacturing systems.

In a two-bin system, when the first container becomes empty through consumption by production, the empty container itself becomes a "signal," indicating that the container needs to be refilled or replenished. During the time required for replenishment of the first container, the second container remains at the workstation, continuing to supply manufacturing. In...