Crane scheduling in batch annealing process

In this paper, we study the crane scheduling problem of batch annealing process to minimize the last job completion (makespan). Some special characteristics of our crane scheduling are contrasted with that of existing two categories. We prove it to be strongly NP-hard and develop a resource assignment problem based heuristic algorithm in a bottleneck level. The heuristics is analysed from an absolute worst-case performance ratio of 3 and an asymptotic worst-case performance ratio is 2 respectively.