Modeling and Control of Wiresaw Manufacturing Process

The objective of the current research is to model and control the wiresaw manufacturing processes in wafer slicing. Other than a few patents in industrial management of wiresaw, the wiresaw manufacturing process has remain poorly investigates. The purpose of this research is to investigate and understand the fundamental mechanism of this critical technology in slicing silicon wafers and ceramic materials. The accomplishments to date include: rolling-indenting model of the ÒFree Abrasive MachiningÓ (FAM) process, elasto-hydrodynamic interaction, stress analysis of the rolling-indenting process, vibration analysis, stiffness control, and FEM analysis of elasto-plastic analysis. The results of the research have provided basis for building the US-based technology in wiresaw slicing process for large silicon wafers. Introduction: Wiresaw has become the technology for future, replacing the current Inner Diameter (ID) saws, for slicing large (3 300mm) silicon wafers for microelectronics fabrication. Wiresaw has also been employed to slice other brittle materials such as alumina, quartz, glass, and ceramics. It is also a very efficient wafer slicing process for its minimal amount of kerf losses and high overall production rates. The process, however, was poorly understood and remains a black art in practicing industry. Since the inception of this research, many industry and research institutes have inquired information about the process. The research results have been well accepted and facilitated the improvement of the process. Three recent areas of recent research results will be reported in this conference. Please refer to the web site http://dove.eng.sunysb.edu/~kao/wiresaw for more details. We have collaborated with our industrial partner, http://www.gt-equipment.com/, on the experimental work to complement and validate the theoretical analysis. Modeling: The manufacturing process of wiresaw is a free abrasive machining (FAM) process. Specifically, the wiresaw cuts brittle materials through the Òrolling-indentingÓ and Òscratch-indentingÓ processes where the materials removal is resulting from mechanical interactions between the substrate of the workpiece and loss abrasives, which are trapped between workpiece and wire. Built upon results of previous investigations in modeling of wiresaw, a model of wiresaw slicing is developed based on indentation crack as well as the influence of wire carrying the abrasives. This model is used to predict the relationship between cutting rate and the mechanical properties of the workpiece together with the process parameters. The rolling, indenting, and scratching modes of materials removal are considered with a simple stochastic approach. The model provides us with the basis for improving the efficiency of the wiresaw manufacturing process by changing the process parameters. Figure: the Òrolling-indentingÓ model Figure: modeling indentation and stresses rolling-indenting Crystal Abrasive Wire V0