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Wire electrical discharge machine cutting (EDM) offers a higher degree of precision compared to other fabrication methods. It involves submerging the subject to be cut in dielectric liquid and using a highly charged carbide wire to remove material across a very small cutting face. Similar to other subtractive manufacturing methods, there is an assumed level of error and imprecision. The most common within the scope of wire EDM cutting is referred to as “bulge error”. This asymmetrical error is largely attributed to the relaxation and dispersion of residual stresses within the cut object relaxing and deforming along the cutting geometry, exasperated with time and length. The contour method is used to map and identify residual stresses within a machined specimen across a plane of observation. Based on Hooke's Law, these stresses can be mapped by evaluating the displacement from the cut plane and specified material properties. The asymmetric nature of bulge error introduces bias within contour mapping analyses by displacing the contour planes beyond the calculable displacement caused by residual stress. Furthermore, adequate fixturing of a specimen is a foundational step in the fabrication process for desirable production processes and reduced machining inaccuracy. This research serves to justify a fixturing solution of test objects cut by wire EDM. A finite element model emulates residual stresses and the wire cutting process to derive a simulated strain. From this simulation, physical experiments can be compared using similar wire cutting scenarios, fixturing, and test specimens to validate the fixtures capability of reducing bulge error.
Engineering | Mechanical Engineering
James Worth Bagley College of Engineering
Department of Mechanical Engineering
Downs, Will and McGee, Sterling, "Bulge Error Reduction Analysis in Wire EDM Cutting Scenario" (2022). ME 4233/6233 Fundamentals of FEA. 34.