Design of Experiments Procedure to Optimize Feedrate in Wire Electrical Discharge Machining

Wire Electro-Discharge Machining (WEDM) is a material removal process that incorporates heat generation through electrical energy and mechanical movement to produce finished designs in electrically conductive workpieces. The WEDM workcenter used in this research is a JAPAX 4G. The unit uses nozzles to guide the wire and apply the dielectric fluid to the workpiece. The wire is the conductive electrode and the dielectric fluid produces a localized ionized field between the workpiece and the wire. The dielectric fluid also, clears the debris and cools the wire. The most common problem in WEDM is the optimization of cycle times. The amount of time needed to produce a finished part determines the profitability of the workcenter. Industry is continually searching for procedures to decrease cycle times and increase profit. This research uses a design of experiments (DOE) method to optimize the WEDM process. The key parameters of the WEDM process are modified during the DOE trials. The results are applied to produce an optimal machining condition. The three conditions: Manufacturers Settings, E-Chip Settings, and Optimized Settings are used to produce the rough-cut of three identical designs. The rough-cut is the first pass to produce a finished workpiece. It is during this pass that material removal rate and the risk of wire rupture are the greatest. The overall cycle time is mainly impacted by the time required to perform the rough-cut. The three designs produced are examined for surface finish. The key parameter settings that are used during the rough-cut must not produce a surface finish that requires the addition of cutting passes to produce the final design. Also, the risk of wire rupture during the rough-cut must be acceptable. If wire rupture were to occur during the rough-cut then all benefits of increased speed are lost.