Sunday, January 18, 2004

Lean Manufacturing (2)

I found interesting material on the net about Lean Manufacturing. It also leads me to the history of Toyota Co. This is what I found, plus more things that I'm adding:

1)At the end of the World War II, Toyoda Sakichi, founder of Toyota Spinning and Weaving company, dreamed of providing cars for the general public, much like Henry Ford’s dream thirty years earlier.
He chartered (hired) Taiichi Ohno to put in place an efficient production system to produce high quality automobiles. Over the next three decades, Ohno developed the Toyota Production System, now known world-wide as Lean Manufacturing. The foundation Ohno’s system was the absolute elimination of waste.

Ohno studied the US manufacturing techniques, and learned a lot from Henry Ford’s pioneer work in assembly line flow. However, the assembly line produced large lots of identical cars. Ohno didn’t have the customer base to imitate the US practice of manufacturing in economic (i. e. large) lot sizes. He was captivated by the US supermarkets, however, where a small quantity of every product was placed on shelves, and as shoppers removed products, the shelves were rapidly replenished (filled or made complete again). He decided to place inventory supermarkets throughout his plant, and found that this technique dramatically lowered the waste of in-process inventory. He named these inventory supermarkets kanban.
Because Ohno was converting a spinning and weaving company to an automobile manufacturer, he already knew how to avoid making bad product. Founder, Toyoda Sakichi had invented an automatic shut-off mechanism that stopped a weaving machine the minute a flaw such as a broken thread was detected. Ohno moved this concept to car manufacturing, where he insisted that each part be examined immediately after it was processed, and the line stopped immediately if a defect was found.
To maximize product flow, standard work sheets were created, but these were not developed at a desk by engineers. They were developed on the shop floor by the workers who know the process. Standard cycle times and kanban shelf space for each item was determined and workflow was leveled. Production workers were like a relay team, handing off the baton (product) to the next person. The handoff required 100% quality and tight timing. If things got delayed, teammates were expected to help each other set up a machine or recover from a malfunction.
Ohno’s aggressive elimination of waste led him to the twin values of rapid product flow and built-in quality. Over time, Ohno discovered that these two values led to the highest quality, lowest cost, and shortest lead time products possible.

2)Traditional manufacturing philosophies stress high utilization of machinery and manpower with little concern for cycle time or manufacturing waste. Conversely, Lean Manufacturing is a philosophy of production that focuses on creating greater production efficiencies through maximizing value-added activities while minimizing waste.

Therefore Lean Manufacturing employs differet methods to minimize the waste and lead time. The methods include:

• The 5S System
• Value Stream Mapping
• Setup Reduction
• Total Productive Maintenance (TPM)
• Cellular/Flow Manufacturing
• Pull Systems/Kanban