Kamran Shahanaghi - Department of Industrial engineering, Iran University of science and Technology, Tehran, Iran
Unes Bahalke - Department of Industrial engineering, Iran University of science and Technology, Tehran, Iran
Hasan Gholami Mazinan - Department of Rail way engineering, Iran University of Science and Technology, Tehran, Iran
Javad Nouri - Department of Computer engineering, Iran University of Science and Technology, Tehran, Iran

In more former studies on assembly line balancing, processing times of tasks were fixed assumed and the problem of assembly line balancing was defined as assigning tasks in work stations with objective functions of minimizing the number of work stations (SALBP-1), minimizing the cycle time (SALBP- 2) and minimizing the cycle time and number of work stations, simultaneously (GALBP). But with considering deteriorating tasks in assembly lines, the processing time of tasks are not be fixed and will be depend on their starting time in the assembly line. Indeed, with consideration the deteriorating tasks in assembly line, the problem of assigning tasks in to work stations changes to assigning and scheduling tasks in work stations. A mathematical model is developed based on 0-1 integer programming with objective functions of minimizing the number of work stations, cycle time and work load deviation. However, these optimization problems fall into the class of NP-hard problems. Finding an optimal solution takes a long time which will be out of acceptable range. For this aim a genetic algorithm is developed approach to the problem of simple straight assembly line balancing. Several examples were presented to illustrate the proposed approach.

Assembly line balancing, Task deterioration, Multi-objective, Genetic algorithm