Research On Process Of EDM Low Electrode Wear Milling For Dificult-to-machine Materials

In the21st century, many industries such as aerospace, military, marinedevelopment, biomedical applications and nuclear industry have put forward higherrequirements to materials. In these industries, many structural materials or functionalmaterials with excellent performances are applied in special working experiment. Whilethese excellent performances the materials have led to a big problem that they aredifficult to machine, so they generally be called “difficult-to-machine-material”. Amongall of these difficult-to-machine-materials, titanium alloys are widely used in industrialmachining. Nowadays, it is really hard and expensive to machine titanium alloys. Thispaper aims at improving material removal rate (MRR) and reducing tool wear rate(TWR) in machining titanium alloys based on EDM milling technology.Firstly, the discipline about electrode wear in EDM milling titanium alloys wasinvestigated. The distribution of energy between anode and cathode, adsorption effect,the properties of electrode, optimal input process parameter, types of dielectric werediscussed respectively, which provided the theoretical foundation for further research.Secondly, The central composite rotation orthogonal design (CCD) had beenutilized to plan the experiments, and response surface methodology (RSM) wasemployed for developing experimental models. Analysis on machining characteristics ofEDM milling was made based on the developed models. In this study, pulse on-time,pulse off-time, peak current, rotation speed of electrode, dielectric flushing pressure andmilling thickness were considered as input process parameters. The processperformance such as MRR and TWR were evaluated. Analysis of variance test had alsobeen carried out to check the adequacy of the developed regression models. The optimalcombination of input process parameters were obtained by multi-objective optimizationmethod.Lastly, since the wear of electrode was inevitable, a mathematical model about toolwear was developed, a new tool wear compensation method based on UG-Post Builderwas constructed. Finally, the experimental result showed that the proposed method wasreliable.Through the study of EDM milling on titanium alloy, the material removal rate wasimproved and the tool wear rate was reduced. Overall, the objectives about highefficiency and low wear for EDM milling on titanium alloys was achieved successfully.And the maximum MRR can reach23010mm~3/min while the minimum TWR was only0.055%.