The Ohno Circle: Watch & Learn!


The most important responsibility a manager has is to continually improve the system of work so his or her people can work more effectively and efficiently, producing higher quality and greater value for the customers. We surface and eliminate the waste in a variety of ways, asking people close to the work for their input, studying how other companies have achieved improvements, bringing in consultants and studying journals.

However, the most effective and least expensive process improvement method may be the simple method of looking and thinking about what you see.

For example, a small team of professionals was asked to determine how to fix the problems with a multi-million-dollar robotics line. This robotic line was designed to prevent stock-outs and excess parts inventory on the assembly line by using bar-coded totes, an overhead conveyor belt, and scanners and switches to send a new tote of replenishment parts to exactly the right workstation.

When a tote was emptied, it was placed on the return conveyor and when the return scanner read the barcode, the tote number would be captured. The scanner would record the emptied tote numbers, and every three minutes this list would be transmitted to the inventory software. Inventory would be decremented for workstations that had been assigned that tote number and a replenishment order would pop up at the material handling station.

The system failed so miserably that the supervisors had to take a complete physical inventory at the start of every shift to correct the inventory records.

The improvement team spent several weeks conducting interviews and studying the floor layout diagram, the process flows, and the computer code to crack a mystery that, as it turned out, could have solved in 20 minutes using the ‘Ohno Circle’ method.

As you may know, Taiichi Ohno is credited for much of the thinking behind the Toyota Production System, and he invented a novel method of making improvements. He would go to where the work was being done, draw a chalk circle on the floor, and stand in it.

He would stand for hours, watching and thinking about what he was seeing. He would look for what was getting in the way of people creating value and he would study the situation to determine what was causing it. This gave him the insight he needed to make lasting improvements.

Of course, the team of problem solvers had toured the line, but while they had looked, they had not watched. If one or more of them had stood in one place long enough to watch carefully, they would have seen the returned totes drop off of the return conveyor and nest one inside another. The next minute, they would have seen someone take the newly dropped empty tote from the top of the stack and use it for the next order. The material handler would key in the tote number, the new workstation destination, and the part numbers being sent there and send the tote on its way — often less than a minute after the tote had dropped off the return conveyor.

That is, the observers would quickly have realized that the tote re-use process was too fast for the information flow — which reported the list of emptied totes only once every three minutes.

Whenever a tote was reused before the list was sent, the inventory of the new workstation would be decremented instead of the inventory at the workstation that had returned the tote. With this insight, the problem was easily solved — change the frequency of the systems updates or change the return tote process so that no totes were refilled within 3 minutes of dropping off the belt. The latter was the easier solution, and a poka-yoke was quickly implemented to make it impossible for a recent tote to be selected and keyed in.

A little bit of watching can tell us a lot.