Thermodynamic Simulation And Process Test In Powder Mixed EDM Of SiC/Al Composites

The SiC/Al composites have attracted much attention due to their good process performance and are widely used in mechanical and electrical engineering,chemical materials,aerospace and other fields.For all that,because of its high hardness,the method of traditional machining will lead to serious tool wear,difficult processing and low processing efficiency.Although electrical discharge machining(EDM)can realize the processing of the composites,it also has the disadvantages of low processing efficiency and poor surface quality.In order to effectively improve the machining quality and efficiency of the SiC/Al composites,this paper proposed a method of the powder mixed electrical discharge machining(PMEDM).Based on the comprehensive analysis of the relevant literature at home and abroad,taking the SiC/Al composites as the research object,the thermodynamic simulation of the powder mixed EDM of the SiC/Al composites was carried out,the polarity effect of the powder mixed EDM was studied,process experiments of the conventional EDM and the powder mixed EDM were completed,and the multi-process target parameters were optimized by grey correlation method.The specific research contents are as follows:Firstly,the development and application status of the powder mixed EDM method and the SiC/Al composites were studied,and the thermodynamic simulation model of the powder mixed EDM of the SiC/Al composites was established.The thermodynamic variation law of the powder mixed EDM of the SiC/Al composites under different peak current and the volume fraction of SiC was analyzed,which provides a theoretical basis for process test research subsequently.Secondly,the positive and negative polarity of the powder mixed EDM of the SiC/Al composites was studied.Under the processing conditions of pulse width of 75 ?s,pulse interval of 125 ?s,peak current of 8 A and powder concentration of 6 g/L,the SiC/Al composites with SiC content of 5%,10%,15%and 20%were used to conduct the positive and negative polarity comparison tests of the powder mixed EDM,and the influence law of different processing polarity on processing time,material removal rate,relative electrode wear rate and surface quality of workpiece was studied.Finally,the experimental study on the powder mixed EDM process of the SiC/Al composites was completed.By comparing and analyzing the orthogonal test results of EDM and the powder mixed EDM,the superiority of the powder mixed EDM in efficiency and performance is intuitively demonstrated.The effects of pulse width,pulse interval,peak current and powder concentration on machining time,material removal rate,relative electrode wear rate and surface quality of workpiece were studied.The grey correlation method was used to optimize the multi-process objective parameters of the experimental results of the powder mixed EDM.And the optimal combination of parameters were obtained are as follows:pulse width of 25 ?s,pulse interval of 125 ?s,peak current of 16 A,powder concentration of 10 g/L,and the influence on the comprehensive process index was ranked as follows:powder concentration>peak current>pulse width>pulse interval.The theoretical research and experimental results shown that the material removal rate is increased by 69.88%,relative electrode wear rate is reduced by 34.91%,the surface roughness is reduced by 41.77%,and the grey correlation degree is increased by 10.47%by using the method of the powder mixed EDM,which effectively improved the processing quality and efficiency,and provided theoretical and experimental basis for the powder mixed EDM of the SiC/Al composites subsequently.