Difficulties in estimation the quality of assembly line balancing problem

The paper describes difficulties in estimation of the quality of assembly line balancing problem (ALBP). The mentioned problem is NP-hard and even optimal solutions can contain idle times. The objective of optimization ALBP is to minimize the number of workstations on an assembly line for a given cycle time (TYPE 1) or to minimize the value of cycle time for a given number of workstations (TYPE 2). Since more than 50 years many exact and heuristic methods were introduced to solve the problem. As a result we get sequence of assigned tasks to the workstations of the assembly line. The additional problem is to choose appropriate solutions because of existing idle times. Some quality performances help to estimate the final results. In this paper efficiency line, smoothness index and time of the line are discussed. Author underlines the problem of differences between cycle time and maximum station load. Numerical examples are presented and conclusion are given.