Research On ECM-EDM Combined Machining Processing

Electrical Machining Technology have recently been wide employed in the automotive, aviation ,aerospace and other manufacturing industries ,especially plays a significant role in the field of aviation and aerospace manufacturing .Electrical discharge machining(EDM) can be used to machine various hard processing materials,and it can machine the special and complex shape surface and parts.However, the recast layer will be generated by EDM processing.The recast layer which is one type of quenching tissue formed by the molten material under rapid-cooling circumstance, often contains micro-cracks, which tend to spread under alternating loads and then result in fracture failure of the component.Electrochemical machining(ECM) removes materials based on the principle of anode electrochemical dissolution. ECM is often used for machining difficult-to-cut materials because electrochemical dissolution is independent of the material hardness and toughness. Additionally, ECM generates no burrs, no stress, and has a long tool life, high material removal rate and good surface quality.In this paper, a combined process for machining profile holes is proposed, in which ECM is employed to remove recast layer formed in EDM. The following work has been done:1. The influence of the EDM parameters on the recast layer has been investigated. The results show that thinner recast layer can be obtained by using positive polarity, narrow pulse-on duration, and low discharge current.2. The effect of the ECM parameters on the removal of recast layer are discussed. The result shows that using high current density,high frequency, low duty ratio, and low concentration of non-liner electrolyte are helpful to improve surface quality .3. The irregular holes without recast layer are obtained by using the optimized parameters of this combined process.