Evaluation of multi-stage electro discharge machining (edm) parameters

Electrical discharge machining (EDM) is a well-established machining process for manufacturing geometrically complex and/or hard parts that are extremely difficult-to-machine by conventional machining processes. However, the process is a complex task due to the nonlinearities of the process parameters. In a whole EDM process, multi-stage machining is generally carried out from rough to finish for minimizing the machining time. In this thesis, the effects of the most important electrical parameters such as discharge current (I), pulse on time (Ton) and pulse off time (Toff) to material removal rate (MRR), electrode wear ratio (EWR), surface roughness (Ra) and average white layer thickness (AWLT) were experimentally investigated for different machining stages. The experimental data was modelled using artificial intelligence techniques and the alternative EDM parameter sets were generated by the help of these models. A multistage strategy and a computer program were developed to determine the required number of stages for minimum machining time. The resulting average white layer thickness of the previous stage was taken as a criterion to determine the machining depth. The machining depth and the corresponding parameters set in each stage according to the desired surface quality, volume and area of the workpiece can be defined by using the alternative EDM parameter sets which were generated by the models. The developed multi-stage EDM strategy and the computer program were experimentally verified.