An exact approach for batch scheduling in flexible flow lines with limited intermediate buffers

The paper presents a mixed integer programming approach for makespan minimization in flexible flow lines. The line consists of several processing stages in series, separated by finite intermediate buffers, where each stage has one or more parallel identical machines. The problem objective is to determine a minimum length schedule for a mix of part types, where identical parts are scheduled consecutively. The limited intermediate buffers between the stages result in a scheduling problem with machine blocking, where a completed part may remain on a machine and block it until a downstream machine becomes available. Numerical examples modeled after real-world surface mount technology lines for printed wiring board assembly are provided and some computational results are reported to illustrate the approach.