Heijunka - production levelling
- Details
- Written by: Super User
- Category: Heijunka - production levelling
- Hits: 28
The greatest dilemma of the world of production is the gap between the nature of customer demand and the requirements of efficient production. The customer wants to find the desired product, at exactly the desired moment, without trouble; production lines struggle to protect their efficiency in the face of constantly changing orders. This tension often results in excess stock, rushed deliveries, low machine efficiency, and exhausted teams. It is exactly at this point that Heijunka, the heart of the Toyota Production System, comes into play: the art of standardizing and balancing production.
So why is Heijunka so vital? As earlier articles have also indicated, the answer lies in the trio of "Muda," which means "waste" in Japanese, "Mura," which means "irregularity," and "Muri," which means "overburden." Heijunka directly targets Mura (irregularity). By holding production volume and mix as steady as possible over a given period of time (for example, a day or a week), it smooths the ups and downs in the system. Thanks to this regularity, overburdening of the machines (Muri) is prevented, and the wastes (Muda) that appear in moments of overload or of waiting idle are minimized. Just as Taiichi Ohno said, we prefer to be the slow but steady tortoise rather than the fast but irregular hare.
So where does this fluctuation come from? As stated in our previous articles, fluctuations in demand are inevitable. The rush at lunchtime in a restaurant, a construction company's increasing workload in the summer months, the seasonal patterns felt at every level of the supply chain. These are natural phenomena. The real problem is reflecting this fluctuation onto the production line as it is. If you release a large order from the customer into production as it stands, everyone works overtime that week, the machines run without stopping, and the following week everything is dead calm. This is destructive both for labor and for machine efficiency.
- Details
- Written by: Super User
- Category: Heijunka - production levelling
- Hits: 33
Today's subject is how the general fluctuation in orders should be managed, one of the questions asked most often about Heijunka and lean production. At root, in every business there is always a phenomenon of decrease and increase that we can call periodicity or seasonality. In some sectors this periodicity occurs within the day, while in others it occurs within the week, the month, and the season. For example, in restaurants orders concentrate at mealtimes and fall at other hours. In the construction sector, by contrast, work slows in periods when the weather is cold and increases rapidly in periods when it is warm.
- Details
- Written by: Super User
- Category: Heijunka - production levelling
- Hits: 27
Balancing production, or the practice of Heijunka*, is from time to time described by some groups as unattainable or imaginary, because it is not fully understood. Yet throughout all the processes in which value is flowing, there are three important causes that do not produce added value. They have been named: Muda (waste), Mura (irregularity), and Muri (overburden). These three phenomena directly affect the system in connection with one another. For example, Mura is at the same time one of the basic causes of Muda. Taking an example from nature on this subject, Taiichi Ohno said the following:
“The slow but consistent tortoise produces less waste and is more desirable than the hare that races ahead and sometimes stops to nap. The Toyota Production System can be realized only when all employees become like the tortoise.”
- Details
- Written by: Super User
- Category: Heijunka - production levelling
- Hits: 32
What is the cost of preparing the production and material plans of a medium-sized business?
In answering this question, many company managers describe this cost as limited to personnel cost. In reality, however, the costs are not limited to personnel cost. What is worse, the plans that are made themselves generate a cost. In particular, main-industry companies cause additional cost for their suppliers with the plans they send.
Let us try to explain the situation with an example. Let us consider a company that, in order to produce a product, must process it one after another on five separate machines. Let the company's planning officer give the plans he has prepared to the machine foremen, and let the foremen produce on the machines according to the plan. What are the losses here? Let us examine them now.
- Details
- Written by: Super User
- Category: Heijunka - production levelling
- Hits: 33
Our customer never wants to know what, when, and how much they will want. They are such a being that, the moment they cannot find even the smallest thing, they become very upset and their satisfaction falls at once. They never forget the difficulty they experienced, and every time we have to negotiate on price they set what they went through in front of us, one by one. And, inevitably, we have to give a discount.
Production always wants to know what, when, and how much it will produce. It has such constraints that, with the smallest change, its efficiency falls, and it takes a long time to reach its former efficiency again. Meanwhile, we too have to work overtime. Costs get out of hand.
Under these conditions, producing, selling product, and giving a delivery date is a miracle; even so, if we are able to sell product, we owe this only to the sales team. Well, in that case, nothing we do for them is enough. So that they can easily find what they want, when they want it, we rent separate warehouses and fill them with stock.
Do you think this situation describes a utopian company?
