The techniques used in the “pull” production system
The "pull" manufacturing system is characterized by producing only what is required, minimizing inventory in process. To achieve this end, several particular approaches have been created, such as those described below:
Just-in Time: In which only the appropriate components, at the precise moment they are required, are manufactured.
Kan-Ban: It is a paper record that enforces just-in-time, moving with each batch of components. This can be automated using barcodes, QR codes, etc.
Manufacturing cells: Combine the requirements of a variety of products so that a set of equipment can produce each of them, as needed. This mainly applies to manufacturing and sometimes to assembly.
Batch-of-One: Refers to the ability to make any combination of items with a batch size as small as one.
Continuous improvement: Refers to the ability to find ways to improve current processes, often by combining and/or eliminating manufacturing activities.
Statistical process control: Referred to monitoring how well the process is working.
The manufacturing process had played a secondary role in product design for most of the 20th century, resulting in many problems when it came to manufacturing the products. While major aspects of manufacturing processes have been researched and implemented in physical devices for many years, the assembly process had very little beyond the rules of thumb to guide it.
Ideas for improving assembly capability and for designing cost-effective manufacturing systems only began to flourish in the late 1970s. During this period, many individuals and companies began to realize that the most rational course of action involved design. of products and the design of manufacturing systems together, which is called concurrent engineering or simultaneous engineering. A more recent term, which involves the entire company as well as suppliers and customers, is known as collaborative engineering.
Manufacturing methodologies – the pull and push systems
Traditionally, there has been a clear separation between the creation of a product and the means through which it is produced. In much of the 20th century, manual production methods were used in different processes, especially those in which assembly was present. However, many important design decisions were worked on behind a desk.
Between the late 1970s and throughout the 1980s, manufacturing industries of all types and sizes wanted to know how they could replace their manual production methods with better processes. In this way, large companies that produced larger volumes of a product determined that automation was the best solution. In this way robots and other programmable machines were developed. Manufacturing plants of this era were characterized by having work-in-process inventory that took up large amounts of space, creating significant costs that did not generate revenue.
In the 1990s, up to the present day, industries of all sizes need to be agile and flexible, so a new paradigm in the field of production was introduced. This approach means that companies are looking to have the ability to respond to any customer very quickly, while minimizing their costs. Thus, the production philosophy changed from making a stock of some product to manufacturing on demand, which required rethinking the way in which production processes should be carried out.
In this framework, Toyota introduced the approach of producing only what is required, with which the "pull" method replaced the "push" method.
In the “push” production method, each stage of the manufacturing process ran at the highest possible speed, regardless of what happened in subsequent stages, which meant having significant batches of inventory in process. To optimize these processes, elaborate simulation methods were created.
In the "pull" method of production, each stage of the manufacturing process works only when the next stage provides notice that it requires inputs. Viewed another way, each step in the process has a customer, either internal or external, to which it responds. Using this system, inventories in process are minimized, being completely eliminated in many cases. The analysis of such a manufacturing system is much less complex than traditional simulation methods.
Producing only what is required is a fundamental concept of "pull" manufacturing systems, which minimizes in-process inventory. Work is not done in any area until the next level says it is ready for input.
