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Study on characteristics of Micro Electrical Discharge Machined surface

Jayakumar Narasimhan, University of Nebraska - Lincoln

Abstract

Micro-Electrical Discharge Machining (EDM), one of the non-traditional machining processes, generates highly complex 3-D features needed in industrial applications. However, surface integrity (such as surface finish and recast layer of the machined surface) critical to the functionality of the product is very difficult to measure without destructive testing. The models developed through this research work predict the surface characteristics and provide guidelines to control them. ^ The results from the tool path generation models demonstrated that accurate surface profiles can be machined by appropriately compensating for tool wear in micro-EDM. A readily available thermal model for macro-EDM was utilized to predict the radius of the crater generated on the surface by micro-EDM and an analytical model was developed to predict the surface roughness. The statistical comparison showed that calculated value from the mathematical model was comparable to the experimental results. The results also showed that the capacitance and the voltage significantly affected the surface roughness. ^ A first order Data Dependent Systems (DDS) model was developed that characterizes the micro-EDMed surface profiles. The experimentally validated model proved that capacitance and voltage played a significant role in the volume of material removed per discharge that correlates to the surface finish. ^ The developed regression model from the metallurgical study can be used to estimate the thickness of recast layer from the surface finish. Thereby, the thickness can be estimated without any destructive analysis. A linear correlation exists between the thickness of recast layer and the surface roughness. ^ To bridge the gap between the research and the industrial shop floor application, an online monitoring system was developed that captured the voltage signal during the actual machining and determined the surface integrity. The subsequent off-line analysis results show that the average gap voltage and the pulse on-time were the significant contributors to the surface finish. ^

Subject Area

Engineering, Industrial

Recommended Citation

Narasimhan, Jayakumar, "Study on characteristics of Micro Electrical Discharge Machined surface" (2011). ETD collection for University of Nebraska - Lincoln. AAI3466534.
http://digitalcommons.unl.edu/dissertations/AAI3466534

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