Reconfigurable Feature Recognition for an Adaptable, Maintainable CAD/CAPP Integration

This paper presents MEDIATOR, a feature recognition system which is designed to be maintainable and extensible to families of related manufacturing processes. A problem in many feature recognition systems is that they are difficult to maintain. One of the reasons may be because they depend on use of a library of feature-types which are difficult to update when the manufacturing processes change due to changes in the manufacturing equipment. The approach taken by MEDIATOR is based on the idea that the properties of the manufacturing equipment are what enable manufacturable shapes to be produced in a part. MEDIATOR’S method for identifying features uses a description of the manufacturing equipment to simultaneously identify manufacturable volumes (i.e. features) and methods for manufacturing those volumes. Maintenance of the system is simplified because only the description of the equipment needs to be updated in order to update the features identified by the system.

Distance Learning of Skills

With the increasing globalization and expansion of the people’s activities, distance learning is getting wide attention. Distance learning is not a computer aided education system alone. What is important is that collaboration over the network is a prerequisite for that, so that the technology developed there will be easily utilized for distance manufacturing and other collaborative activities over the network. When we come to think of integrating design and manufacturing over the network, the problem of skill comes up. Skill plays a very important role in manufacturing. But most of the systems developed so far have been focusing their chief attention toward how rigously they can represent design and manufacturing knowledge and experience in terms of symbols, and non-symbolic approaches are still few. It is believed that motion occupies a large portion of skills, but the present systems being such, and in additon, such media as TV, video, etc are one way from a teacher to a student so that it is still very difficult to learn skills over the network, since skill learning requires much interactive processes. Otherwise, students find it very difficult what part of the model motion they should concentrate their focuses. If a teacher can edit the motion of a student and a student can watch how his or her motion is edited, the student will understand more easily what is wrong with his or her motion., and can identify where his or her attention should be focused. Based on this idea, we have developed a preliminary system for distance learning of skills to demonstrate the effectiveness of the approach.

Computer Supported Product Development Through Integration of CAD, Rapid Prototyping and 3D-Digitizing Helps the Productivity of Former East German Companies

In socialistic countries, customer satisfaction and the market conditions were not of high priority: Some selected parts of the market products were of satisfactory costs and quality to customers. Quality and costs of a product decide on its success in the world-wide market. The wishes and expectations of the customer for a high-quality and low-priced product continue to grow, however, with the desire for faster availability of this product. The customer determines also the delivery time and other competitive factors as the durability of the product. At present the trend goes towards shorter product life cycles, which in turn requires reduced time spent on the product development. With these complex market requirements and growing diversity of the products the engineer faces new challenges in his development tasks. It can be paraphrased as follows: In reduced lifecycles a quality-assured and advantageous product has to be developed despite increasing complexity of the design and demands for reduction of material used, manpower and monetary spending. For the solution of this complex problem the following suggestions are tested and implemented: • Structured design process for the development process, • Simultaneous work where ever possible during the development stages, • Employment of modern resources for the product development, • Use of information technology and • Implementation of rapid prototyping for models and in secondary manufacturing processes. An important research field at the Department of Mechanical Engineering Design at the Otto-von-Guericke-University Magdeburg is research and further development of productive procedures and tools for the realization of a computer integrated product development process. This process includes the effective application of technologies to produce the prototypes for presentation, producibility analysis and production. Of particular interest is the closed process chain (loop) from Solid Modeling via Rapid Prototyping and 3D-Digitizing where the entry point of this process chain depends on the needs of the application or particular interest of the innovating company. Information for faster and more competitive preparation, verification and Re-Engineering of existing and established products, which have to be adjusted to the world-market needs, will be made available. The results of this applied research offer opportunities to display new developed products for the lagging industries in the former East Germany, and furthermore arranging for necessary venture capital to produce the product, to gain information about possible suppliers and manufacturing opportunities in order to minimize the investors’ risks of an enterprise.

The Role of Compliance in the Design of MEMS

A great majority of the available micro devices and systems use compliant (or flexible) structures and mechanisms. This trend in design takes advantage of micromachining techniques while satisfying the constraints imposed by them. By citing relevant literature, this article briefly notes the influence of compliance on the mechanical design and analysis of Micro-Electro-Mechanical Systems (MEMS).

Application of Convex Hull for Tool Interference Avoidance in 5-Axis CNC Machining

In this paper, a methodology of applying convex hull property in solving the tool interference problem is presented for 5-axis NC machining of free-form surfaces. Instead of exhausted point-by-point checking for possible tool interference, a quick checking can be done by using the convex hull constructed from the control polygon of free-form surface modeling. Global tool interference in 5-axis NC machining is detected using the convex hull of the free-form surface. A correction method for removing tool interference has also been developed to generate correct tool path for 5-axis NC machining. The inter-surface tool interference can be avoided by using the developed technique.

Characteristic Measures for the Representation of Manufactured Surface Quality

In this paper, we investigate four methods that yield mathematical measures to analyze the precision of surfaces of manufactured parts. These four methods, namely the autocorrelation function, the Fourier spectrum, the Karhunen-Loève expansion, and a fractal-wavelet representation, are applied to surfaces produced from grinding processes. The first two methods are standard methods used in the surface analysis literature for qualitative signal characterization. The Karhunen-Loève expansion method, used in various signal processing applications, has never been applied to the field of surface characterization and representation. The fractal-wavelet representation has been previously proposed by the authors; its suitability to generate characteristic measures is investigated in this paper. The existence of characteristic measures of surface precision should aid designers in choosing process and design parameters and in comparing the precision between competing machining processes. The use of such measures is essential in taking a forward step towards integrating the fields of design and manufacturing.

Collaborative Design System for Electromechanical Products

This paper gives an overview of a collaborative design system (CDS) for electromechanical products. To reduce design costs and to manufacture high-quality products, it is well known that concurrent engineering (CE) is a very efficient approach. Three-dimensional (3D) CAD system and engineering database system are essential components of CE. The CDS is an environment to realize CE. By creating 3D models in a computer and performing some simulations such as mechanical, electronic, software simulation and integrated simulations, it is possible to estimate functions, assemblability, manufacturability and so on, before making prototype models. In this paper, we outline the CDS and mainly discuss the total information management system (TIMS) which makes an important role of the CDS. This paper describes the implementation experience of some functions of the TIMS.

An Investigation of Vector and Parallel Processing Applied to Solid Modeling

Solid modeling is a very useful industrial tool in the manufacture and design of industrial parts and assemblies. As a tool in the industrial workplace it has to be able to respond quickly to changes in design. To do this, the intersection algorithms between the solids have to be speeded up. Optimizations such as vector and parallel processing traditionally supported by supercomputers have the potential to solve this problem. A solid modeler was developed based on the boundary representation approach using a half-edge data structure. Those parts of the solid modeler code that could be vectorized were identified. A method was tested which allows loops involving linked lists to vectorize. It was also shown that this solid modeler has an inherent parallelism that can be exploited. Results are presented for vectorization and parallelization. The practical limits to both vectorization and parallelization are highlighted. Improvements to the geometric intersections algorithms are suggested to take advantage of vector and parallel processing. Results of the speedups possible using these algorithms are presented.

A Parallel Solution Strategy for Finite Element Models

This paper presents a method for naturally decomposing finite element models into sub-models which can be solved in a parallel fashion. The unique contribution of this paper is that the decomposition strategy comes from the geometric features used to construct the solid model that the finite element model represents. Domain composition and domain decomposition methods are used to insure global compatibility. These techniques reduce the N2 behavior of traditional matrix solving techniques, where N is the number of degrees of freedom in the global set of matrix equations, to a sum of m matrices with n2 behavior, where n represents the number of degrees of freedom in the smaller sub-model matrix equations.

A Knowledge-Based System for Machining Operation Planning in Feature Based, Open-Architecture Manufacturing

Within the Integrated Design And Manufacturing Environment (IMADE), operation planning provides a mapping from geometric design primitives to machining operation sequences for manufacturing processes. Operation planning includes tool selection, machining parameter selection, and tool path generation. An object oriented approach to program structure is adopted, whereby features, operations and tools, inherit behaviors and attributes from the appropriate class-hierarchies for the part, the manufacturing operations, and tooling classes. A detailed example is presented illustrating the operation planning search algorithm. Scripts are generated by the individual machining operations for execution on a machine tool. Tooling information is maintained in an object-oriented database through the FAR libraries for Common LISP. Examples of particular process plans show that the inherent trade-offs between specified precision and machining time can be investigated. An Open Architecture Machine Tool (MOSAIC-PM) has been used to machine the parts created by the feature based design and planning system. The novel contributions of this paper relate to the demonstration of “seamless” links between, a) design, b) planning, and c) actual fabrication by milling.