Wire electrical discharge machining (WEDM) as a subtractive rapid manufacturing tool

A modern Wire Electrical Discharge Machining (WEDM) system is capable of producing more complex geometry than 2D, 2½D or ruled surface parts. The improved geometric capability and the other well-known advantages, such as capability of cutting hard materials, ignorable cutting force, make WEDM a potential Rapid Prototyping (RP) process. Unfortunately, limited capability in process planning automation for six-axis WEDM requires significant process planning time and effort. This research presents the development of a methodology and the associated algorithms for using WEDM as a subtractive rapid prototyping process. Specifically, an automatic process planning system is built for six-axis WEDM process. A boundary representation is used to model part geometry and the manufacturability of a part on a six-axis WEDM machine is addressed in this research as well. In particular, a stereolithography (STL) file is used as the input for the algorithms. Global tangent visibility, fabrication orientation, and the setup requirements and numerical control code are the output. Similar to the importance of visibility analysis in the automation of the milling process planning, global tangent visibility analysis is the foundation in the automation of WEDM process planning. In this research, an algorithm to calculate the global tangent visibility for polyhedral computer-aided design (CAD) models was developed. A greedy algorithm is also developed to classify the global visibility results and to determine the setup plans for producible geometries on six-axis WEDM. Number of setup orientations is determined automatically for six-axis WEDM machines. A method to generate machine instructions automatically based on tangent visibility results and setup plans was also developed. In order to verify the methodology, a verification system is built; and several sample parts are fabricated. The methodology and algorithms developed in this research result in a systematic automatic process planning method for applying WEDM as a subtractive RM tool. Those results are not limited to WEDM process; it can be applied to other in-line cutting systems such as laser, water jet and hot wire foam cutters.