Lean Production System ◾ 33
scheduled at each department—or pushed along—regardless of the needs of
the downstream process. These schedules are based on the inventory and
WIP levels recorded in the database, which usually vary widely from actual
levels. Thus, workers and supervisors make extra, “just in case,” and WIP
accumulates.
Overproduction
Taiichi Ohno saw overproduction as the root of all manufacturing evil.
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Overproduction means making things that don’t sell. Here are some of the
related costs:
◾ Building and maintenance of large warehouses
◾ Extra workers and machines
◾ Extra parts and materials
◾ Extra energy, oil, and electricity
◾ Extra forklifts, tow trucks, pallets, and skids
◾ Extra interest payments on loans
◾ Hidden probl ...