Assembly line is a flow-oriented production system where the productive units performing the operations, referred to as stations, are aligned in a serial manner. Any assembly line comprises a finite set of work elements called tasks. Each task is characterized by an operation processing time and a set of precedence relationships, which specify the allowable orderings of the tasks. To develop a good assembly system, good observation is required. However, observing real manufacturing system is very expensive and sometimes cumbersome. The rapid rate at which the whole process takes place, the interaction between workers, and the different transition times between workers make it increasingly more difficult for a human being to make correct decisions regarding how fast each operator should work in order to continue the process while at the same time keeping productivity high and throughput at an acceptable level. However with a simulation models, we can explore how an existing system might perform if altered, or how a new system might behave before the prototype is even completed. Thus modeling and simulation technique help managers in decision making by saving on costs and lead times
