ULINO: Optimally balancing U-shaped JIT assembly lines

Traditionally, assembly lines are arranged in a straight line. The design of such a line requires tasks to be grouped into stations such that the line efficiency is maximized. This problem is known as the assembly line balancing problem. However, as a consequence of introducing the just-in-time production principle, it has been recognized that arranging the stations in a U-line has several advantages over the traditional configuration. For solving different versions of the U-line assembly line balancing problem, we propose the branch and bound procedure ULINO which is applied directly and in the framework of search methods. Experimental results indicate that these procedures perform well and that the U-line configuration frequently improves the line efficiency compared to traditional lines.