EWAB Flow Technology
EWAB and Cell Manufacturing
The U-shape Cell, a conceptual metaphor
When experts, authors and consultants describe the difference of an old functional factory with lean manufacturing, the production process is overly simplified, probably in order to fit on one page.
The old process is often described the way production looked in the 1950´s with a number of workstations/machines grouped together based on the type of operation they performed and with a manual workforce loading and unloading each machine. The new Lean approach is often described as the workstations/machines arranged in a U shape according to the process which allows the operators to serve several workstations with the shortest possible walking distance. Already in the early 1970´s, European manufacturing plants were arranged and linked by process and not by function and automation was introduced to reduce labour and improve throughput and quality.
Anyone that has worked in the real production world knows that manual handling of high precision parts and quality demands are counterparts, and that manual handling will create more defects than anything else. Yet, it is interesting to note that so many are taking this conceptual metaphor as the way for manufacturing in times of extreme component quality requirements.
EWAB Flow Technology combining the Functional and the Flow Factory
Different factory principles such as the functional factory and the flow factory both have their advantages but they are contradictions. Both the Transfer line and the Cell approach are attempts for a flow factory but neither provide the level of lean that is required
EWAB Flow Technology is designed with ”pull and re-route” functionality arranged as a functional factory layout for maintenance purposes yet at the same time acts as a flow layout to provide maximum throughput!
U-shaped or In-Line Layout
The U-shaped flow layout configuration is to be preferred as in and out feed can be located in the same end, materials flow is on the “outside” and the operators and maintenance have sufficient space on the “inside”.
Many factories are limited by space which leads to a long and narrow layout. This long and narrow layout imposes both operations and maintenance limitations that, in the worst case, can even become a constraint in regards to optimum throughput.
Even the simplest process can have a multitude of configurations. Most layouts are traditional and will have built in constraints that prevent “pull and re-routing” capabilities.
The transfer line
The sequential transfer line approach was popular for many years, but is today limited to very specific processes. Transfer lines is what often comes to mind when conveying equipment is discussed. The configuration with parallel operations with no cross feeding capability is the one being used most. This configuration can at best provide limited re-routing functionality. The transfer lines tend to be custom made and can rarely be re-used or re-configured.
Another trend has been the work cell approach where each operation/machine is more or less an isolated island. This concept is easy to understand and to implement but very difficult to manage as it needs supervising systems and often computer software to keep track of the process as an uncontrolled flow of batches between the islands will cause chaos. Stand alone work cells does not provide either the cybernetic pull nor the re-routing capabilities that one piece flow requires.
The thinking behind having many independent work cells is to have the flexibility to produce a high variety of low demand products, while maintaining the high productivity of large scale production. The layouts tend to become functional layouts rather than flow layouts when flexibility is the main driver. High flexibility and high volume does not work well together as high volume in a work cell environment will cause a lot of unnecessary movements, a build up of inventory and reduced quality and throughput.
Many companies have tried the cell approach, but realised that in real life it is a contradiction to all of the elements in "the seven wastes" as it requires inventory between the work cells in order to function.
Many consultants are however promoting the work cell approach, as this solution is something a consultant can propose and yet not have to be responsible for.
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