Finding Cutter Engagement for Ball End Milling of Tessellated Free-Form Surfaces

In fabricating free-form surfaces, ball end mills are mainly used to reach the final surface finish requirements. In the milling processes, cutter engagement value measures what portion of the cutter is involved in machining at a given instant of time. This paper presents geometric algorithms for estimating cutter engagement values for ball end milling processes of tessellated free-form surfaces. The cutter engagement value calculated here can be used later on in generating efficient cutter paths, as well as performing adaptive feed rate controls.

Implicit Solid Modeling for Mesh Free Analysis

In traditional solid modeling the boundaries of the solid are represented using parametric equations. Even though the application of implicit equations has also been explored, they have not been widely used. Interest has been rekindled recently due to application of implicit equations to mesh free engineering analysis. In this paper, an implicit representation scheme for solids is presented where the boundaries of primitive solids are defined using implicit equation of surfaces. To ensure that the equations are axis independent, the characteristic functions for the implicit equations are defined by interpolating within hexahedral elements. Primitive solids are defined by sweeping closed 2D profiles. The boundaries of these profiles are defined using implicit equations of curves. Implicit equations can be used for constructing “step function” of the primitives and their Boolean combinations. The step functions of a solid has a unit value inside the solid and zero outside and can be used for computing volume integrals needed for mesh free analysis.

A Methodology for Creating Ontologies for Engineering Design

This paper describes a methodology for developing ontologies for engineering design. The methodology combines a number of methods from social science and computer science, together with taxonomies developed in the field of engineering design. A case study is used throughout the paper focusing upon the use of an ontology for searching, indexing and retrieving of engineering knowledge. An ontology for indexing design knowledge can assist the users to formulate their queries when searching for engineering design knowledge. The root concepts of the ontology were elicited from engineering designers during an empirical research study. These formed individual taxonomies within the ontology and were validated through indexing a set of ninety-two documents. Relationships between concepts are extracted as the ontology is populated with instances. The identified root concepts were found to be complete and sufficient for the purpose of indexing. A thesaurus and an automatic classification are being developed as a result of this evaluation. The methodology employed during the test case is presented in this paper. There are six separate stages, which are presented together with the research methods employed for each stage and the evaluation of each stage. The main contribution of this research is the development of a methodology to allow researchers and industry to create ontologies for their particular purpose and to develop a thesaurus for the terms within the ontology. The methodology is based upon empirical research and hence, focuses upon understanding a user’s domain models as opposed to extracting an ontology from documentation.

Fractal-Agent Based Cooperation Style of Industrial Alliance

Internet technology provides a convenient and low-cost platform for the cooperation among two or more manufacturers. Industrial alliance is a networked cooperative enterprise group linked by the similar product and technology relying on such an Internet platform coupled with supporting cooperation system. However, with increasing bulkiness and complexity of the cooperation system, it is a significant issue in industrial alliance to simplify the cooperation style among these manufacturers. The hierarchical industrial alliance is always classified into alliance level, enterprises level and departments level. Based on the self-similarity principle of fractal, the paper analyzes the similarity concerning both function structure and workflow of the industrial alliance. To describe these self-similar organizations at different levels while developing information system, fractal-agent theory is raised here. Moreover, based on the fractal-agent theory, a new cooperation style of industrial alliance is put forward, by which a cooperation pool of fractal-agents and the multi-level nested dynamic sub-alliance can be established to simplify their cooperation activities. It’s practically proved that the technology can efficiently enable the industrial alliance to fulfill rapid reconfiguration.

Converting Molecular Meshes Into Smooth Interpolatory Spline Solid Models

The study and understanding of molecules, once the domain of blackboards and stick-and-ball models, has become more and more exclusively linked to the use of computer-aided visualizations. Our project seeks to return the physical facsimile to the biologists, allowing the use of tactile senses while interacting with and manipulating a physical model, thus aiding educational and research endeavors. To increase the effectiveness of such a tool, the model is constructed such that multiple levels of information are viewable within the single physical form, stressing the interaction between the assorted components within the molecule. We use the term 3-D physical visualizations to refer to the fabricated model, to avoid confusion with the common usage of model as a virtual representation on the computer. To effectively combine multiple components into a smooth manufacturable physical visualization, all components of the model must be in a homogeneous format. Our research sets forth a method for converting triangulated mesh data, as provided by the molecular modeling packages, into spline models. Spline models have the attractive qualities that they are smooth without triangular facets, can be combined using traditional boolean operations (and, or, not), and can be directly fabricated using modern CAD/CAM techniques. Our method divides the polyhedral representation into multiple rectangular grids, then fits interpolatory spline surfaces to the data in each region, while focusing on smoothly stitching the boundaries and corners of the spline surfaces in order to create a near G1 continuous model.

Rule-Based Process Selection of Hole Making Operations for Integrated Process Planning

Process selection as a part of CAPP has captured significant attention in CAPP research. Procedures have been developed for backward and forward algorithms in process selection. Most of these procedures lack the complete integration of process selection into CAPP system. In this paper, we present the results of the development and prototype implementation for process selection module for hole making operations for integration with Math Based Manufacturing System already in use in industrial partner. We have developed architecture and implemented module for rule-based machining process selection of hole making operations. The architecture enables the interface from the Process Selection prototype to Math Based Manufacturing System (APPS). The prototype also includes the user interface for interaction with the process selection procedure. Actions for starting prototype from APPS, performing process selection steps and sending the result back to APPS have been developed and implemented.

Usability of Web-Based Design and Manufacturing Systems: Case Study of Micro Machining

In this paper, web-based design and manufacturing systems are compared with a commercial CAD/CAM system from the point of usability. The web-based systems included in this study were MIcro Machining System (MIMS) and SmartFab. In the MIMS architecture, a 3D model in STL format was read via a web browser, sent to the web server for toolpath planning, and NC codes were generated to be fed back to the designer through the web connection. In the SmartFab system, SolidWorks was used as the design interface with provided modified menus for micro machining. These additional menus were created by SolidWorks API that also provided web-based links to the toolpath planner. In the commercial CAD/CAM case, without using any web connection, SolidWorks or CATIA was used for design, and PowerMill was used as a CAM tool. For each design and manufacturing system, accessibility, user-friendliness, toolpath-reliability, and processing time were compared. Total 91 students tested these systems in undergraduate CAD class, and the feedback showed better performance of the web-based system in accessibility, user-friendliness, and processing time. However, reliability of the web-based system showed necessity of further improvement.

Simulation of Mating Between Non-Analytic Surfaces Using a Mathematical Programming Formulation

In this paper we describe a new method for simulating mechanical assembly between components that are composed of surfaces that do not have perfect geometric form. Mating between these imperfect form surfaces is formulated as a constrained optimization problem of the form “minimize the distance from perfect fit, subject to non-interference between components.” We explore the characteristics of this mating problem and investigate the applicability of several potential solution algorithms. The problem can be solved by converting the constrained optimization formulation into an unconstrained problem using a penalty-function approach. We describe the characteristics of this unconstrained formulation and test the use of two different solution methods: a randomized search technique and a gradient-based method. We test the algorithm by simulating mating between component models that exhibit form errors typically generated in end-milling processes. These typical component variants are used as validation problems throughout our work. Results of two different validation problems are presented. Using these results, we evaluate the applicability of the mating algorithm to the problem of mechanical tolerance analysis for assemblies and mechanisms.

Metrics for Degree-of-Openness of Engineering Information: Recognizing the Value of Standards-Based PLM — Part 2

Over a product lifecycle, many engineering tools are used to create computer-based models that need to interact. This poses interoperability problems because of the conflicting formats of the models and differing scopes of the tools. One proposed solution is an open standards-based product lifecycle management (PLM) framework. However, the use of open standards is hindered by the lack of knowledge regarding their actual and potential usage in current engineering processes. To overcome this hurdle and evaluate the opportunities and extent to which open standards can be used in such PLM frameworks, we develop three metrics for degree-of-openness of engineering information: compatibility, coverage, and completeness. To demonstrate the usefulness of the proposed metrics, we assess circuit board design information that is transferred between native models of an electronic CAD system and the STEP AP210 standard (ISO 10303-210). This preliminary experience shows that each of the three useful metrics provides a limited aspect of degree-of-openness, and the combination of these metrics provides a single more holistic degree-of-openness indicator.

A Cooperative-Collaborative Design System for Multi-Disciplinary Mechanical Design

The emergence of computer and network technology has provided opportunities for researchers to construct and build systems to support dynamic, real-time, and collaborative engineering design in a concurrent manner. This paper provides an understanding of the product design in a distributed environment where designers are in different geographic locations and are required to be involved in the design process to ensure successful product design. A design process model that captures the major interactions among stakeholders is presented, based on the observation of cooperation and collaboration. The stakeholders’ interactions are divided into activity and system level to distinguish the interactions in group design activities and design perspective evolution. An initial computer implementation of the design model is presented. The design system consists of a set of tools associated with design and a management system to facilitate distributed designers to support various design activities, especially conceptual design. Our research emphasis of design collaboration in this paper is: (i) Model a Cooperative-collaborative design process; (ii) Support synchronized design activities; and (iii) Structure the complex relations of various design perspectives from engineering disciplines.