Models are used to describe how the system works. A "theory" or equations that describe the system's boundaries and behavior through its input parameters is needed to get a mathematical model for the system.

What is a manufacturing system?

DeGarmo, Black and Kohser, in their book Materials and Processes in Manufacturing, define a manufacturing system in the following general terms:

A manufacturing system inputs materials, information, workers, and energy to a complex set of elements known as machines or machine tools which can be characterized. The materials are processed and gain value. Manufacturing system outputs may be either consumer goods or inputs to some other process.

Manufacturing systems are subject to continous change. They are very interactive and dynamic.

We distinguish four kinds of classical manufacturing systems and one new manufacturing system:

• The classical systems are the job shop, the flow shop ( or transfer line), the project shop, and the continous shop.
• The new system is known as cellular manufacturing system.