Printed Circuit Board (PCB) assembly plants face growing product diversity and shorter product life cycles, making production planning in these plants increasingly complex. A specific part of the planning process is allocation of PCB-types to machines. Under certain circumstances this allocation cannot be changed very frequently, and therefore it should be decided carefully. A heuristic algorithm is described which can support a planner in the allocation process. PCB-types often have similar parts lists. In the first step of the procedure, this characteristic is used to group PCB-types into clusters in order to reduce total changeover time. In a second step clusters are allocated to machines. Test results show that the procedure allocates the PCB-types efficiently.