Integer programming models for the design and balancing of flexible assembly systems

The paper presents several integer programming formulations for the design and balancing of flexible assembly systems in which different product types are assembled simultaneously. The system is made up of a set of assembly stations linked with an automated material handling system. Each station consists of a single machine or of identical parallel machines, usually assembly robots. The problem objective is to assign tasks to stations with limited staging capacities in order to balance station workloads and station-to-station product movements subject to precedence relations among the tasks for a mix of product types. Integer programming formulations are also proposed to simultaneously select the number of stations and the number of parallel machines at each station and to allocate tasks to stations. Numerical examples are presented to illustrate applications of the various models proposed.