Path optimization for multi-axis EDM drilling of combustor liner cooling holes using SCGA algorithm

Abstract

Multi-axis electrical discharge machining (EDM) drilling technology is widely used in the manufacture of film cooling and jet cooling holes of combustor liners. However, there can be more than 3000 film cooling holes with variant orientations in a typical combustor liner. Drilling of thousands of holes without process planning will result in a low machining efficiency. Traditional path optimization methods are carried out in a workpiece coordinate system, which is usually not optimal when applied to multi-axis machining processes. Aiming at minimizing the total non-productive time in a combustor liner multi-axis EDM drilling process, a mathematic model, which takes tool traveling time, tool switching time, and compensation moving time into consideration, is firstly derived. To solve the optimization problem efficiently, a spectral clustering/genetic algorithm (SCGA) is applied as the model has a large number of 0–1 variables. To improve the search performance, pairwise inter-reshuffle (PIR) based initial population and modified mutation are utilized. The performance of SCGA is evaluated by solving a 3616-hole optimization problem and the results are compared with those by other heuristic methods. Comparison results show that the SCGA significantly outperforms other comparison algorithms in terms of minimum non-productive time and convergence speed.