Study Of Mechanical Vibration Aided Submersed Gas- Jetting Edm

EDM in gas is an environmental-friendly machining method due to the use of harmless gas. It has much lower Electrode Wear Rate (EWR) and much better manufacturing flexibility compared with the traditional EDM. Its relatively narrow discharge gap, however, will result in high short circuit rate and low Material Removal Rate (MRR). Based on EDM in gas, a new machining method named submersed gas-jetting EDM is proposed in 2007 and gets its quick development thereafter. Compared with the EDM in gas, submersed gas-jetting EDM can offer significantly higher MRR and better workpiece surface quality in the same machining condition. In fact, the MRR of submersed gas-jetting EDM is still at a low level. With the assisting of the high-speed platform, submersed gas-jetting EDM can get a MRR of 35.2mm3/min with an unexpected high EWR of about 40%. In this paper, a novel machining technology named mechanical vibration aided submersed gas-jetting EDM is proposed to get high MRR, low EWR and good workpiece surface at the same time, In the machining process of vibration aided submersed gas-jetting EDM, the workpiece is fixed on the vibration table.A vibration table using voice coil motor was developed and tested in this paper. A series of experiments were conducted to get better machining performance by optimizing the parameters of the vibration table. The experimental results show that the MRR and finished workpiece surface quality of can be greatly improved when the frequency was 300Hz and the amplitude was 22.4μm. Moreover, the influences of pulse duration, pulse interval, peak current, gas pressure and rotational speed were studied on the processing performance of mechanical vibration aided submersed gas-jetting EDM. The MRR can reach a MRR of 45mm3/min and the EWR still stayed at very low level if proper working parameters are selected. Vibration aided submersed gas-jetting EDM is likely to be one of the most promising machining methods and can be extended to the areas that require high MRR and better surface quality and low EWR.Numerical simulations of the energy distribution between the two electrodes of the submersed gas-jetting EDM were also achieved. The energy distribution of workpiece influenced by the pulse duration and peak current were investigated from theoretical, experimental and numerical perspectives. It was found that the energy distribution coefficient Fa was directly related to the pulse duration and peak current value. The distribution coefficient was 0.3 and 0.4 respectively, corresponding to high and low level of pulse duration and peak current. The diameter of the crater predicted by the numerical simulation coincides with the experiment. This study is helpful in understanding the discharge mechanism of submersed gas-jetting EDM method.