Getting Out of Line with Lean
The lean manufacturing approach was born as a challenge to the familiar

"The technical achievements of the industry have been remarkable, but whether it has been possible for anyone to approach the industry with an absolutely open mind, free from tradition, is another matter."
—Henry Ford

WHY do people resist beneficial change? Anyone engaged in the lean manufacturing transformation will ask that question more than once. There are some obvious answers – wariness, politics, lack of imagination, sheer mulishness – but Peter Senge, a brilliant analyst of organizations, has a more subtle and useful one. New insights are rejected, he says, "because they conflict with deeply held internal images of how the world works, images that limit us to familiar ways of thinking and acting." Senge’s interesting point is that the new insight might be rejected even when the familiar ways aren’t very effective. All they have to be is familiar.

Take standing in line, something about as familiar as breathing. Think back to your last trip to the mall or the grocery store. Was there a line at the register? Of course. There always is. But why are there lines in the first place? Essentially, it’s because of randomness. The store doesn’t know exactly when you are coming or when you are going to finish your shopping. They have a rough idea of how many people shop on which days at which hours, of course. But only a rough idea. They don’t know exactly when or how long it will take or which line you will choose or how many items you will buy. For them, you are a random event.

Back in 1905 a Danish telephone engineer named A. K. Erlang studied the predictability of such things. Eventually, he invented a theory of lines – or queues, as the Europeans say. Among other things, he even devised a formula that could be used to calculate the expected waiting time on a given line.

Accepting lines and waiting as inevitable, traditional manufacturing depends on Erlang’s brainchild and its successors in queue theory. And it’s true that in a traditional approach there is plenty of randomness. Customer behavior is often random. Parts and supplies arrive in a random fashion. Randomness also creeps into production. The result, as we all know, is frequent fire-fighting, a certain amount of yelling and screaming and the inevitable waste of time and energy.

But lines aren’t inevitable. Lean manufacturing’s pull system approach is essentially a way to eliminate as much randomness as possible. The kanban communicates a customer’s need exactly. In a well-run lean system, production will equal demand, so again randomness is reduced.

Why try to eliminate randomness? Because, according to lean thinking, it creates waste. Lean manufacturing draws heavily on the Toyota Production System, brainchild in many ways of Toyota’s Taiichi Ohno. Ohno was dedicated – some might say obsessed – with removing waste from the process by any means necessary.

One waste that especially outraged him was waiting: machines and workers idled by a delayed part, a slower station or a change-over. Like his idol Henry Ford, Ohno felt quantity and speed were overrated by manufacturers. For him, the answer was not to go faster and make more but to remove as much randomness from the process as possible. Production leveling, kanban, visual management and other lean techniques were the result.

Ohno praises his inspiration Henry Ford for his refusal to take things for granted. "Ford," he says, "thought flexibly about things without ever getting caught in existing concepts." As for Ohno himself, he describes his approach even more radically: "I have always tried to view things upside down." Is randomness (and waste) really inevitable?

Or is it time to stand that idea on its head?

Dr. Arlie Hall is an adjunct professor for the Center for Robotics and Manufacturing at the University of Kentucky College of Engineering.

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