Lean manufacturing

Jidoka

Providing machines and operators the ability to detect when an abnormal condition has occurred and immediately stop work. This enables operations to build in quality at each process and to separate men and machines for more efficient work. Jidoka is one of the two pillars of the Toyota Production System along with just-in-time.

Jidoka highlights the causes of problems because work stops immediately when a problem first occurs. This leads to improvements in the processes that build in quality by eliminating the root causes of defects.

Jidoka sometimes is called autonomation, meaning automation with human intelligence. This is because it gives equipment the ability to distinguish good parts from bad autonomously, without being monitored by an operator. This eliminates the need for operators to continuously watch machines and leads in turn to large productivity gains because one operator can handle several machines, often termed multiprocess handling.

The concept of jidoka originated in the early 1900s when Sakichi Toyoda, founder of the Toyota Group, invented a textile loom that stopped automatically when any thread broke. Previously, if a thread broke the loom would churn out mounds of defective fabric, so each machine needed to be watched by an operator. Toyoda’s innovation let one operator control many machines. In Japanese, jidoka is a Toyota-created word pronounced exactly the same (and written in kanji almost the same) as the Japanese word for automation, but with the added connotations of humanistic and creating value.

Heijunka

Think about this: Lean promotes pull, and at the same time pushes for standard work. In truth, the two concepts don’t play very well together. Standard work promotes rhythm. Pull promotes responsiveness. If your customers don’t buy at an even pace…well, you can see the problem.

In Lean, Heijunka aims to find a way to level the demand on the factory to prevent having wild shifts in production. In effect, a heijunka system uses actual demand from customers over a long period to set production rates, and then stabilizes the short term demand based on those average rates. That way, you only have to shift production schedules to match long term changes in customer demand. You don’t chase the small, day-to-day fluctuation.

In the example above, the average demand is 205 units. If you set your production at 41 per day, you would be balanced with your demand, on average. In the example above, though, you would end up with 4 extra units the first Monday (overproduction), and then run 20 units behind the second Monday. But, at 41 per day, you’d end up flush on the third Friday-even though you might have only gotten the daily demand to match production a couple of times.

For the three week period, you were right on the money. Plus, you kept from having to wildly shift production around in your facility. Just remember–during those three weeks, you were either pulling from a finished goods inventory, or increasing your order backlog whenever your demand wasn’t identical to your production.