Abstract: Methods, systems and apparatus, including computer programs encoded on computer storage medium, for processing parts using machine tool workstations. The machine tool workstations are grouped into multiple groups, where each group includes workstations of the same type. For each of the multiple groups, data representing parts to be processed by the type of workstations included in the group are transmitted to a combinatorial optimization problem solver. Data representing a sequence of ordered subsets of the multiple parts that produce a reduced setup time for the workstations in the group are received from the solver. An average delay time associated with the generated sequence of ordered subsets of the collection of parts is computed. If the average delay time is less than the predetermined threshold, parts are released according to the generated sequence of ordered subsets of the collection of parts to the group for processing.