The performance of most manufacturing processes depends on numerous parameters and their interactions. Most of the time, selection of an appropriate set of machining parameters is done based on experience, trial and error or both. Electro-discharge machining (EDM) process is complicated and random in nature. The large number of parameters and the inherent complexity of removal mechanism taking place in EDM make it even more difficult to select machining conditions for optimal performance. The objective of this study is to provide information on the relationships between the key input variables and resultant surface roughness and to develop a response model for surface roughness optimization utilizing factorial designs, direction of steepest descent method and response surface methodology (RSM). Experiments were setup and executed to understand the individual and combined impact of factors that included the following input variables: gap voltage, depth of penetration, electrode type, and average current and pulse duration. Six iterations were executed in the direction of steepest descent for minimization of surface roughness. Pulse duration and average current have been shown to have significant effect on surface roughness. Depth of penetration was found to be insignificant and was eliminated in the subsequent experiments. Graphite electrode gave better surface finish than copper electrode at given factor level combination. The results shows that graphite electrode can be used in finishing operation while achieving the unprecedented surface quality that was only attainable with copper electrode in such operations. The best surface roughness 0.96um Ra was achieved. Response surface model based on a central composite experimental design was established to give better idea about the relationship between significant parameters, their interactions and surface finish. A higher order model is developed that can relate process inputs to response. The results obtained may be used to recommend process setting to improve process robustness and to get the desired surface roughness.
Library of Congress Subject Headings
Electrolytic polishing--Mathematical models; Grinding and polishing--Mathematical models; Response surfaces (Statistics)
Department, Program, or Center
Industrial and Systems Engineering (KGCOE)
Mehta, Bhairav, "Response surface methodology of Die-Sink-Electro-Discharge machined surfaces" (2002). Thesis. Rochester Institute of Technology. Accessed from
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