Preliminarily Experimental Study on Servo Control Strategy for Dry Electrical Discharge Machining

In traditional liquid EDM, huge carbon emissions, and the process is not environmentally friendly. The emergence of electric discharge machining in gas (DEDM) has unfolded a new situation of sustainable development of EDM. However, the problems of poor discharge stability and low machining efficiency have restricted the application of DEDM. Considering that servo control is an important factor affecting the discharge state and machining performance, while related research is rarely reported up to now, we make an exploratively study on the servo control of DEDM to understand its feature and aim to improve the discharge stability and machining efficiency. The relative discharge ratio, machining efficiency, electrode wear and surface roughness with different control strategies were compared and analyzed using a self-built ball screw EDM servo system, and obtained a more effective improvement compared with traditional servo strategy in DEDM. It is found that PD control strategy improved the effective discharge ratio by 40.4% and machining efficiency by 136.55% compared with conventional control strategy. This work also analyzed the servo characteristics under different gas media (oxygen, nitrogen, argon) and putted forward servo optimization scheme, the experimental results verified the effectiveness of improving DEDM from servo strategy, which indirectly proved the matching characteristics of medium and servo in EDM.