A Dynamic Programming Based Process Planning Selection Strategy Considering Utilisation of Machines

Computer-aided process planning (CAPP) has been recognised as a key element in computer-integrated manufacturing (CIM). Despite the fact that tremendous efforts have been made to develop CAPP systems, the benefits of CAPP in real-life manufacturing environments are not obvious. One of the main difficulties in applying CAPP in real manufacturing settings is the missing link between generated process plans and shop-floor activities. The assumptions that the shop floor remains static and there are unlimited resources available have caused a typical CAPP system to make a repetitive selection of the same most desirable machines for manufacturing different parts. When process plans for various parts are finally sent to the shop floor, process bottlenecks normally arise, making the generated plans ineffective. Some efforts have been made in the integration of process planning and shop floor activities; however, the problems associated with the lengthy time and impractical attempts at the generation of process plans, remain unsolved. Since in most cases, it is possible that several alternatives exist for machining a part by using different equipment, a stage-type network structure can be constructed. This paper introduces a dynamic programming based process plan selection strategy, enabling the efficient solution of this stage-type network prob-lem. In this proposed strategy, the use of workstations is also taken into consideration so that the resulting plan is valid for the conditions that exist on the shop floor at the time an order is released. A case study has been provided to substantiate the effectiveness of this proposed strategy.