Information flow = production flow
Production takes place on demand and on call!
The flow of information runs counter to the flow of production.
If you let your production run in a continuous flow, the first effect you get is how much time it takes to design a product and bring it to market. Products take months or years to be designed and finished. In a flow, products can be brought to market within weeks. Womack and Jones claim that by using continuous flow, most productions can save up to 75% of their time. In fact, with a lean system the producer can also react quickly to customer requirements, which brings us to the pull principle.
The common approach of a production process is to produce from left to right. This means that the information flow is the same as the production flow and is not dictated by the end customer. This type of production makes it impossible to determine the actual demand. The consequences are often large inventories or the wrong performance at the wrong time in the wrong place. By the pull principle the customer triggers the production. The production is thus carried out according to demand and on call. The information flow from right to left ensures that only what is actually required is produced. Starting from the end customer, the next link in the process chain always requests the performance of the upstream station. In the context of the construction industry, a trade triggers the required advance performance. In this way, considerably fewer resources are tied up and the process can be brought into a continuous flow.
Pull principle through technical innovation
The push principle is used in book sales, for example. It is difficult for publishers to assess the demand for a book before it is published. However, in order not to be sold out when a book is published, they produce a large number of books as a precaution. Even if the book sells very well at the beginning, it is not possible to predict when these sales will collapse. So production is kept up as long as people buy the book. However, a slump in sales usually occurs very quickly, while the adjustment of production is delayed. For this reason, publishers throw away vast quantities of new books every year because there is no demand for them. In contrast to this are eBooks which, due to their digital availability, are only "produced" when the customer wants them. Here, the application of the pull principle means that eBooks are usually much cheaper than the book in paper form.