Study On Surface Roughness Of B₄C Ceramics By EDM And Multiobjective Optimization

The advanced ceramic possess high hardness, high wearable, corrosion resistance, low density, lower thermal conductivity as well as friability .In spite of their exceptional mechanical and chemical properties, ceramic materials have only achieved a partial acceptance in the field of industrial applications due to the difficulties in processing and the high costs associated with their manufacture. Take a wide view both here and abroad scholastics' research and theory,toward conductive ceramics electrical discharge machining is a good processing method.The boron carbide (B 4 C) ceramic was used in the experiments in the text ,the research is about EDM of small holes on B 4 C ceramic .The conclusions which based on lots of experiments and be founded of analysis of the data show that the surface roughness has relative to processing parameter ,and a multiobjective optimization has been carried out.First ,the comparative study has been carried out on the influence of the design factors of pulse time ,pulse interval and intensity on surface roughness. For the sake of showing the impact tendency more clearly, the data to be show by figure .As can be observed in figures Ra parameter tends to increases significantly when pulse time and intensity increase. Conversely, Ra parameter tends to decrease with the increase in pulse interval.Monofactorial test and analyses is the foundation of the next step multifactor analyses .after finding out the influence of the design factors of pulse time ,pulse interval and intensity on surface roughness, we having considered the influence of the interaction of factors to surface roughness .Using the orthogonal polynomial regression design method obtained a three-element and three dimensional regression model. The model shows the tendency of each factor and the interaction of them in roughness .For the sake of validate if the model is accurate , the curve should been optimized and analyzed .And carried out another experiments to proof the result which the model shows is tally with the fact. The conclusion is that the interaction of pulse time , pulse interval and intensity can not be ignored ,they all have influences in surface roughness .The curve on the one hand it could control the surface roughness, it be able to select process parameter according to the accuracy requirement; on the other hand it can prediction the process outcome by the process program , reduction in the numbers of rejects and accident rate.In addition to surface roughness, material removal rate and electrode wear were studied in the text. By the orthogonal polynomial regression design method obtained two models the one shows the influence of the design factors of pulse time ,pulse interval and intensity on material removal rate, another shows the influence on electrode wear .According to each objective significance level match with homologous weight coefficient ,combined the three models to a big one. Then apply MATLAB to solve minima and the processing parameter. The experiment proved that the outcome was credibility,and could be used to guiding the practice work .This multiobjective optimization model can option quotiety according to manipulator's various requirements, in turn to gain various process variables under various requirements.In all, the reasonable electrical parameter can improve ceramics surface quality. The influence of the design factors of pulse time and intensity on surface roughness is stronger then pulse interval, Ra parameter tends to increases significantly when pulse time and intensity increase. Conversely, Ra parameter decrease with the increase in pulse interval. After adjusting the electrical parameter and their combinations, be able to obtained better surface quality and as best as one can to depress electrode wear, also can complete work quickly.