A flexible manufacturing system (FMS) is a manufacturing system in which there is some amount of flexibility which allows the system to react in the case of changes, whether predicted or unpredicted. This flexibility is generally considered to fall into two categories, within which are numerous other subcategories.
The first category, machine flexibility, covers the system's ability to be changed to produce new product types, and ability to change the order of operations executed on a part.
The second category of flexibility within an FMS is called routing flexibility, which consists of the ability to use multiple machines to perform the same operation on a part, as well as the system's ability to absorb large-scale changes, such as in volume, capacity, or capability. The whole FMS is commonly controlled by a central computer. It is not always necessary that on increasing flexibility it also increases productivity.