A Hybrid-Coded Genetic Algorithm Based Optimisation of Non-Productive Paths in CNC Machining

In order to optimise the non-productive paths in CNC machining under entry or exit constraints (such as in laser engraving and flame cutting), a hybrid-coded genetic algorithm (HCGA) is proposed in this paper. There are two chromosomes in the HCGA. One chromosome, called the master chromosome, uses a natural number-coded mode, and represents the sequence of productive contours. The other chromosome, called the slave chromosome, uses a binary-coded mode, and represents the entry or exit nodes of the productive contours. The two chromosomes use the same evaluation function and selection mechanism, but the crossover and mutation operators are different. The coding and genetic operators for open, closed and mixed productive contours are discussed in detail. The result shows that the HCGA is simple but effective for the optimising of non-productive paths in CNC machining.