Gemba Keiei by Taiichi Ohno, Chapter 35: The Monaka System

How many Japanese words do we have in the Lean lexicon? Do we really need another? It’s a rhetorical question, but would you rather have “sweet azuki bean jam wafer system”? I thought not. “Replaceable core system” also works, if you must. However, Taiichi Ohno gives us the monaka system.

“Dies are not general purpose items. So here is something we did.” Taiichi Ohno goes on to explain the challenge of making dies that are reusable as general purpose tools rather than specialized tools. While the press machine is general purpose (can be use to make many different types of products by changing the die) the die itself is typically for only one type of part.

The monaka is a Japanese sweet that is made from a sweet bread-like crust and a sweet bean filling in the middle. The same crust can be used and filled with different “monaka” center to make different varieties of this Japanese sweet. So Ohno is making an analogy of the outer part of the die being similar to the outside crust of this food and the core of the die being the monaka or sweet bean part of this food.

Here is a picture of gourd-shaped monaka snack from a store in Tokyo. The black in the middle is the sweet azuki bean. Click on the links in blue letters between the two red squares on the bottom of this page to see other examples of tasty monaka.

Ohno says that while the sweet bean spoils if cooked ahead (overproduction) you can make the crust ahead an then cook the sweet bean filling to demand when you get the order. He also says it is a waste not to make the crusts in advance, and wait until you have an order and then struggle to make them all at once. It sounds very much like he is saying “build ahead” for the crusts, even when you don’t have orders, in anticipation of orders. It is a very odd thing that he is making an exception here and actually promoting overproduction of crusts.

The idea with the die is to have the middle section hollow so that a core can be replaced and the “crust” of the die reused. Ohno admits there are challenges to this, but that this idea is being attempted in some areas. He says it will take five or ten years to go completely in this direction. As he said this back in 1989, I would be interesting in hearing from someone at Toyota just how far they did go with the monaka system.
Ohno says that this type of versatility and the ability to reuse general purpose dies and equipment is characteristic of the Toyota method.

He goes on to say that there are three elements to running a business: man (people), materials (or more broadly “things”) and money. Companies must generate a profit in order to be able to continue to exist and contribute to society. Ohno says you can make money in three ways. First by being good at selling things, second by being good at managing money, and third by reducing cost.

When making sales is easy, the gemba gets lazy about reducing cost. As long as times are good you may not notice but as it becomes more challenging to make sales and as it gets harder to make money through financial instruments, engineering work and work on the gemba become most important, says Ohno.

Ohno points out the difference between having 500,000,000 yen in cash or 500,000,000 yen in the warehouse as inventory. On the one hand you can use the cash to to make money through investments in financial instruments while the inventory will cost you 10% interest to the bank. You can pay dividends on profits to shareholders on one hand, interest to the bank on the other.

“When people hear cost reduction they tend to think of it as an accounting function. But accounting can’t do cost reduction.” Taiichi Ohno says it’s all up to what you do on the gemba to make a profit, pay your taxes and contribute to your country.