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This paper presents an overview of the recent advances in modeling, simulation and structured synthesis that are pushing ahead the capabilities and efficiency of CAD tools for integrated data converter design. First, a hierarchical design methodology and a common framework with standardized interfaces are shown to be essential to create a design environment that is flexible enough to cover a wide range of specifications and applications. The different approaches for data converter modeling and simulation are then reviewed and compared, ranging from purely electrical simulators to state-of-the-art behavioral analog-digital simulators. In particular, it is shown how behavioral models of data converters are emerging as a powerful solution for complex system simulations with highly reduced computational requirements. Next, the key steps in the automatic synthesis of data converters are discussed, and state-of-the-art synthesis systems are compared and illustrated with some practical design examples. Finally, the progress in tools for testing and design for testability of data converters is described.

An indirect method of using a CAD-CAM system for ceramic restorations may have advantages over the direct method. The direct method of producing CAD-CAM ceramic inlays and onlays involves one long patient session. A camera is used to scan the cavity and the computer records the parameters. Then the computer guides a milling machine to form a ceramic block into the proper shape. Adjustments are sometimes necessary and can be time-consuming. In the indirect method, dentists prepare a stone model of the tooth with the cavity and adjacent teeth. Then the CAD-CAM system can be used to mill the ceramic inlay between patient appointments. All adjustments can be made by fitting the inlay in the stone model instead of the actual tooth. The final ceramic filling can then be set into the patient's cavity at a second session. This method allows for shorter appointments which may be more convenient. Also, more than one dentist can share the CAD-CAM machine.

A computer software has been developed to speed up the design process of automatic degating molds used for injection molding of plastic balls. Following an introduction to the ball making process and the associated mold design consideration, the algorithm and formulation of the software are presented. To demonstrate its versatility, the software developed is adopted to design both testing and production molds that best meet the design and production requirements. Two testing molds were built. While one was used to verify the gate size predicted, the other was built to confirm the workability of the automatic degating design. The results of testing runs have also been used to finalize the details for designing the production mold. The software developed is compact enough to be run on an IBM/PC compatible and has the capability to communicate with commercial CAD/CAM systems to provide necessary drawings or CNC files for mold fabrication.

The generation of correct and efficient plans for machining mechanical components requires the identification of features such as holes, slots and pockets, which are associated with distinctive manufacturing processes. This paper discusses an automatic feature recognizer that extends the state of the art in several directions. The recognizer decomposes the total volume to be machined into volumetric (i.e., solid) features that satisfy stringent conditions for manufacturability, and correspond to operations typically performed in 3-axis machining centers. Unlike most of the previous research, our approach is based on general techniques for dealing with features with intersecting volumes. Feature interactions are represented explicitly in the recognizer's output, to facilitate spatial reasoning in subsequent planning stages. The feature finder's architecture combines partial evidence from various sources such as nominal surface geometry, tolerances, attributes (e.g., threads), and design form features. A generate-and-test strategy is used. OPS-5 production rules generate hints or clues for the existence of features, and post them on a blackboard. The clues are assessed, and those judged promising are processed to ensure that they correspond to actual features, and to gather information for process planning. An incompletely-specified solid feature, represented as a partially-filled frame, is associated with each promising hint. Computational geometry techniques are used to produce the largest volumetric feature compatible with the available data. The feature's accessibility, and its interactions with others are analyzed. Interactions are represented by segmenting the feature into 'optional' and 'required' volumes. Because some of the proposed features may rely on faulty hints, these are tested for validity in a verification phase. The validity tests ensure that the proposed features are accessible, do not intrude into the desired part, and satisfy other machinability conditions. The process continues until it produces a complete decomposition of the volume to be machined into fully-specified features. The recognizer is implemented in a rapid prototyping test bed consisting of the KnowledgeCraft(TM) environment tightly coupled with the PADL-2 solid modeler, and running on Sun workstations.

An optimal approach to the rough machining of sculptured parts with least machining time is presented. The contour map cutting method is used to generate CNC tool paths based on the CAD model of sculptured parts. The part and stock geometry related parameters, including the number of cutting layers and the distributions of cutting depth, and the process parameters of feed rate and depth of cut, are optimized. The method can automate CNC programming for sculptured part rough machining, considerably improve productivity, and lower production costs. Two examples are used to illustrate the approach and its advantages.

This article presents research into automating some lift planning practices common to industrial construction contractors and owners. A detailed investigation of heavy-lift planning methods was conducted through a series of interviews and lift studies with expert lift planners. This investigation documented a wide variety of manual and computer-aided lift planning methods to perform similar types of planning tasks. Based on the information collected from these interviews and lift studies, a structured systems model was developed of the typical heavy-lift planning process. This structured model is used as an architecture for the development of computer software to aid key planning tasks. An examination of major planning tasks indicates that significant reductions in direct planning costs and indirect construction heavy-lift costs are possible through the implementation of computer-aided planning procedures. Computer-aided procedures would also improve the overall quality of lift planning practices through the automation of tasks which are difficult to perform and are critical to heavy-lift planning accuracy.

Interested in rapid prototyping (RP) systems, but can't justify the $50,000 to $550,000 purchase price? No problem. Consider one of many service bureaus that specialize in producing models and prototype […]

Various finacial considerations are forcing hardware vendors to adapt an interconnected computer-aided designing/computer-aided manufacturing (CAD/CAM) system. This new network system allows interplatform access to companies' data, thus, resulting in a much faster marketing and documenting of consumer products. Different networking technologies aimed at enhancing the performance of such systems are continually being introduced commercially.

The Space Shuttle Columbia's Remote Manipulator System (RMS) was developed using highly-advanced computer-aided designing/computer-aided manufacturing (CAD/CAM) tools. SPAR Aerospace of Canada employed CAD/CAM technology to simulate the complex maneuvers to be performed by the RMS in outer space duringthe Shuttle's mission. The technology has enabled design engineers to give the RMS all six degrees of freedom which account for its excellent maneuverability.

The CAD-CAM (computer-aided design/computer-aided manufacturing) technique may be an effective method for making ceramic veneers to fit the teeth of patients requiring restorative dentistry. Restorative dentistry is the replacement by artificial means of a missing, damaged or diseased tooth or teeth. A study compared the use of the CAD-CAM method to the refractory method for making ceramic veneers for 30 human maxillary central incisors. The ceramic veneers made using the CAD-CAM method were comparable to those made in the laboratory using the refractory method. The interfacial gap was approximately the same for CAD-CAM veneers and laboratory-processed veneers. Veneers made in the laboratory frequently needed contouring of facial surfaces. CAD-CAM veneers often required contouring of the internal surfaces of the veneer next to the prepared tooth.

We were a company struggling to learn to ride a tricycle, and we went out and bought a bicycle. After buying a bicycle, the aspiring cyclist must learn to ride [...]

An analysis of the growth and control of the microstructure and properties within a computer-aided design/computer-aided manufacturing (CAD/CAM) system is given. A mathematical model is used to forecast the microstructure and properties from the material processing used and the material composition. The material studied is a specially hardened Al-Li-Zr alloy from the Aluminum Company of America. The particle size, distribution, the free zone width, the critical resolved shear strength and yield strength were all computed by using the model.

This article reports on ten field studies of the implementation of CAD/CAM in Canadian manufacturing firms of a three-year period, focusing on the implementation efforts of the sponsors (patriarchs) and champions (evangelists) in each case. Although the patriarch appeared critical in the new technology involved, it was the evangelist who stayed with the project throughout its life and whose efforts were critical to its successful implementation and integration. The successful evangelists were those who fulfilled three basic roles (pathfinding, problem solving, and implementing) and who demonstrated faith and persuasion. The authors offer prescriptions for senior management with regard to the selection and management of project champions in the implementation of Advanced Manufacturing Technologies. (Reprinted by permission of the publisher.)

Aircraft designers are using digital design tools such as CAD and software development systems to combine the physical and functional characteristics of a product. With today's design tools, it is much easier to alter and customize designs. Details of models and simulation of aircraft designs are presented.

The details of in-office computer aided design/computer aided manufacture (CAD/CAM) devices, that allows fabrication of tooth-colored inlays and onlays, crowns and veneers in one appointment, are presented. CAD/CAM devices are best suited to dentists who accomplish many single-tooth or single quadrant restorations. The advantages and disadvantages of CAD/CAM are also presented.