Study On The Additive And Technology In Powder Mixed EDM

Powder-mixed electrical discharge machining (PMEDM) is a novel technologywhich is introduced from electrical discharge machining (EDM). Through addingpowder particles in pure processing oil, these particles are involved in dischargeprocess, hence, having a significant impact on the EDM process. It plays animportant role in the precise manufacturing and aerospace. Therefore, it has becomeone of immediate areas of research focus in electro-machining field nowadays.This paper mainly analyzes the research prospect and the development ofPMEDM after scanning a lot of literature and data. It discusses the influence ofpowders on discharge process, the PMEDM technique and surface properties ofsamples. Finally, a study has been carried out to optimize the process parameters ofPMEDM. Response surface methodology has been used to analyze the expertiments.This work will perfect the system of PMEDM theory.Firstly, we studied the function of powder particles in electric field during thedischarge process based on PMEDM mechanism.With the change of dielectriccoffecient and the distortion of electric field in the particle surface, it has a biginfluence on the discharge state, enlarges discharge channel and decreases theinterelectrode capacity. Therefore, it significantly increases the working stability.Weexplained the state of the discharge process by the plasma theory, analyzed thedischarge process and reasonably expound the influence of powder particles on thedischarge process with the fluid light theory and Townsend theory.Secondly, we analyzed the properties of powders and the major components ofthe imported powders. Besides, a new powder additive wa s fabricated. Comparingthe self-made powder additive with the imported powder additive and the domestic,we get the influence of a variety of powder additives on the peak current to therough degree of surface, in addition to pulse on time to electrode wear, gap voltageto processing speed and the different electrode area to surface roughness. Then,some tests had been carred out to analyse the surface properties, including themicro-structure of surface, the micro-hardness of surface, the elemental compositionof surface and the corrosion resistance. It is necessary to summarize the effect ofdifferent powders through theory analysis of the test consequence.Finally, we have made optimization design to the process parameters ofPMEDM, peak current, pulse on time, concentration of the powder and electrodediameter were chosen as variables to study the process performance in terms of Response surface methodology has been used to plan and analyze the experiments.The’Design Expert8.0.7’ software was used for the analysis of ANOVA andregression model. The experimental results indicate that the most importantparameters are peak current and pulse on time for the responses. MRR shows anincreasing trend with the increase in powder concentration which shows that MRRwill increase further with further decrease in concentration. EWR decreases withlower range of electrode diameter but then decrease. There is discernibleimprovement in surface roughness of the work surfaces after increasing theelectrode diameter. However, SR decreased when the electrode diameter exceeds acertain value. Most important parameters affecting selected performance measureshave been identified and optimum process conditions have been found. Besides,recommended optimal conditions have been verified by conducting confirmationexperiments. After optimizing the parameters and a full set of processing craft, a diesteel Asp-23and SiC/Al composites surface(50mm) is successfully machined withRa0.175μm and0.450μm.