Automated system for welding-based rapid prototyping

The manufacturing of form-fit-function components, rather than just form/fit parts, is currently a major issue in rapid prototyping (RP). As a deposition process, gas metal are welding (GMAW) has shown promise for RP of metallic parts. In current RP systems, slicing and planning are done based on STL files, and system implementation and post-processing are designed according to the deposition processes used. Due to the significant difference between the welding process and the existing deposition processes, the authors have developed a dedicated technology, including slicing/planning, system implementation, and post-processing for RP using GMAW as the deposition process. For form-fit-and-function testing, a special RP system, including software and hardware, is developed. This system is capable of handling tolerance specifications and material properties. A novel metal transfer control technology is used to precisely control the size and frequency of the droplet in order to improve the deposition accuracy. The part to be prototyped is given by a CAD surface or a solid model in the standard IGES format. A friendly and integrated environment, referred to as welding deposition wizard (WDW), has been developed to slice the part, plan the deposition parameters, and control the deposition process. Test results show that the system can process various models in IGES format with general entities. The model is sliced according to a comprehensive survey of the tolerance, the speed, and the implementation feasibility. The minimization of ignition times, the ignition control, and the crater filling control are incorporated in the planning algorithm for deposition parameters. The slicing and planning algorithm also optimizes the transition from interior to outline pass. The planned deposition parameters ensure the required density and deposition height are achieved. In current RP systems, the deposition parameters, for example, the intensity and travel speed of the laser beam in Stereolithography, are constant. In the developed system, the deposition parameters, including the travel speed. torch angle, welding current, and are voltage, are changed to achieve the required density and geometry. Unlike Current STL-based approximation algorithms, the outline of each layer is deposited with vector motions to obtain the original geometry of the part. The interior is filled with a raster fill pattern to obtain a high deposition speed. (C) 2001 Elsevier Science Ltd. All rights reserved.