An object-oriented bill of materials system for dynamic product management

In this paper, the bill of materials (BOM) system is defined as the central hub of a general product data management (PDM) system that provides essential data for running a manufacturing system to produce products. Information that is relevant to products and their components is defined in the BOM. The information is critically related to data from product design, manufacturing planning, production management, procurement, inventory control, and accounting within a company. A conventional BOM structure (or product configuration), which manages data only in a stand-alone relational database management style, cannot satisfy the needs requested by all departments within a company. A BOM should relate to and communicate with other domains of the information system. In this research, a newly designed BOM system uses the object-oriented programming (OOP) concept to represent product information. The object-oriented BOM (OOBOM) system can capture and encapsulate data that will simultaneously serve the information needs of various departments. In order to manage product data dynamically, the system provides several interfaces for easy data access and manipulation. The linkage between BOM and its corresponding CAD/CAM system is enabled through the X-window manager: thus an integrated PDM environment is developed. This product management approach improves the consistency and efficiency of product data representation.     

Applying case-based reasoning for product configuration in mass customization environments

Product variation and customization is a trend in current market-oriented manufacturing environment. Companies produce products in order to satisfy customer's needs. In the customization environment, the R&D sector in an enterprise should be able to offer differentiation in product selection after they take the order. Such product differentiation should meet the requirement of cost and manufacturing procedure. In the light of this, how to generate an accurate bill of material (BOM) that meets the customer's needs and gets ready for the production is an important issue in the intensely competitive market.

The purpose of this study is to reduce effectively the time and cost of design under the premise to manufacture an accurate new product. In this study, the Case-Based Reasoning (CBR) algorithm was used to construct the new BOM. Retrieving previous cases that resemble the current problem can save a lot of time in figuring out the problem and offer a correct direction for designers. When solving a new problem, CBR technique can quickly help generate a right BOM that fits the present situation.     

Modeling and fabrication of artistic products based on IFS fractal representation

Contemporary computer-aided design (CAD) and computer-aided manufacturing (CAM) theories and systems are well developed for analytical and free-form objects, but neither can deal with all artistically appealing objects efficiently. Artistically appealing objects are common in, for example, jewellery and furniture decoration. Therefore, it is valuable to explore more suitable modeling and manufacturing method for artistically appealing objects.Fractal geometry has been employed for modeling natural objects that cannot be described easily by Euclidean geometry. In this paper, one type of fractal solid — the Iterated Function System (IFS) fractal — is proposed for modeling artistically appealing objects in a computational form. A Radial-Blossoming Tree (RBT) data structure is worked out for fractal solid modeling in a CAD platform. Traversal algorithms have been devised to extract necessary information from the RBT for generating the toolpath for a layered manufacturing (LM) process, so that a physical fractal object can be built and the fabrication of a fractally represented artistic product can be realized.     

Applying case-based reasoning for product configuration in mass customization environments

Product variation and customization is a trend in current market-oriented manufacturing environment. Companies produce products in order to satisfy customer's needs. In the customization environment, the R&D sector in an enterprise should be able to offer differentiation in product selection after they take the order. Such product differentiation should meet the requirement of cost and manufacturing procedure. In the light of this, how to generate an accurate bill of material (BOM) that meets the customer's needs and gets ready for the production is an important issue in the intensely competitive market.The purpose of this study is to reduce effectively the time and cost of design under the premise to manufacture an accurate new product. In this study, the Case-Based Reasoning (CBR) algorithm was used to construct the new BOM. Retrieving previous cases that resemble the current problem can save a lot of time in figuring out the problem and offer a correct direction for designers. When solving a new problem, CBR technique can quickly help generate a right BOM that fits the present situation.     

X international conference “systems for computer-aided design,manufacturing, and product data management” (CAD/CAM/PDM-2010)

Information

X international conference “systems for computer-aided design, manufacturing, and product data management” (CAD/CAM/PDM-2010)     

一个基于知识的二维模具CAPP／CAM系统MEKCAM

ＣＡＤ／ＣＡＰＰ／ＣＡＭ系统的一体化是计算机智能制造管理系统和计算机集成制造系统等的核心部分和重要研究课题，本文论述一个基于知识的柔性电路板模具ＣＡＰＰ／ＣＡＭ系统－ＭＥＫＣＡＭ。首先讨论ＭＥＫＣＡＭ的结构及功能，然后介绍该系统所使用的有关知识和算法，最后，我们给出ＭＥＫＣＡＭ的实现方法及系统评价。     

An integrated manufacturing planning assistant — IMPA

In this paper, we describe our development of a fully integrated manufacturing planning assistant (IMPA) system, which is able to: (1) interpret the finished part requirements directly from the designer's CAD systems or solid modelers without user intervention or special feature coding; (2) check the machinability of a designed part; (3) automatically generate a process plan, a tool path and an NC (numerically controlled) code, and (4) support interactive user modification of the resulting plans, tool paths and NC code. A demonstration version of the system was designed to provide automated assistance for the planning of machining processes on three-axes NC machine tools. The underlying architectural concepts and reasoning algorithms can be extended to more complex machines such as four-or-more-axes NC machines. CAD, CAE, and CAM including robotic, FMS (flexible manufacturing system) and NC machines are widely used in industry today. There is increasing interest in automation of factory control software Merchant, (1988); this includes automating the generation of the control programs — that is, in developing systems which will automatically produce the NC code for machining the part, given a model of the part, the shape of the raw material, and the machine specifications. With such systems, there are several difficulties in the manual preparation of an NC program code such as, long and tedious calculations, high risk of error in data preparation, etc., which need to be eliminated. This is a critical step toward the integration of CAD and CAM into a truly concurrent engineering and manufacturing environment.     

A Visibility Sphere Marching algorithm of constructing polyhedral models for haptic sculpting and product prototyping

This paper presents a Visibility Sphere Marching algorithm of constructing polyhedral models from Dexel volume models for haptic virtual sculpting. Dexel volume models are used as the in-process models representation during interactive modification in a haptic virtual sculpting system. The stock material represented in a Dexel volume model is sculpted into a designed model using a developed haptic sculpting system. The sculpted Dexel volume models are converted to polyhedral surface models in STL format by the proposed visibility sphere marching algorithm. The conversion turns out to be an interesting and challenging problem. The proposed visibility sphere marching algorithm consists of three sub-algorithms: (i) roof and floor covering, (ii) wall-building, and (iii) hole-filling algorithms. The polyhedral surface models converted from the Dexel volume models can then be input to and processed by available computer-aided manufacturing (CAM) or rapid prototyping systems. The presented technique can be used in virtual sculpting, CAD/CAM, numerically controlled machining verification and rapid prototyping.     

Robust uniform triangulation algorithm for computer aided design

This paper presents a new robust uniform triangulation algorithm that can be used in CAD/CAM systems to generate and visualize geometry of 3D models. Typically, in CAD/CAM systems 3D geometry consists of 3D surfaces presented by the parametric equations (e.g. surface of revolution, NURBS surfaces) which are defined on a two dimensional domain. Conventional triangulation algorithms (e.g. ear clipping, Voronoi-Delaunay triangulation) do not provide desired quality and high level of accuracy (challenging tasks) for 3D geometry. The approach developed in this paper combines lattice tessellation and conventional triangulation techniques and allows CAD/CAM systems to obtain the required surface quality and accuracy. The algorithm uses a Cartesian lattice to divide the parametric domain into adjacent rectangular cells. These cells are used to generate polygons that are further triangulated to obtain accurate surface representation. The algorithm allows users to control the triangle distribution intensity by adjusting the lattice density. Once triangulated, the 3D model can be used not only for rendering but also in various manufacturing and design applications. The approach presented in this paper can be used to triangulate any parametric surface given in S(u,v) form, e.g. NURBS surfaces, surfaces of revolution, and produces good quality triangulation which can be used in CAD/CAM and computer graphics applications.     

An Application of Computer Graphics and Networks to Anatomic Model and Prosthesis Manufacturing

Computer graphics has now matured in medical applications from 2D and 3D presentations for diagnosis and the planning of surgery and therapy to become the key step in making hand-held models of custom prostheses. The system described here delivers 3D shape information to create skeletal models, plan corrective surgery, and directly manufacture prostheses. Implants and anatomic models are manufactured using computed tomography (CT) image data and a system to generate Instructions for numerically controlled machines. The system combines clinical imaging, an algorithm for 3D edge detection, computer communications, and computer-aided and manufacturing (CAD/CAM). This integration of technologies brings recent advances in computer-aided design and manufacturing to the local community CT scanning clinic in a cost-effective manner. Via computer communications, several hundred remote medical imaging centers can have their CT scanners connected on-line to CAD/CAM facilities that one could not support alone. Operators of the remote CT scanners bear only the cost of computer communications equipment to being their patients this service. We use the clinical course of several patients in whom prostheses have been implanted to describe this technology.     

Interchanging spline curves using IGES

Current CAD/CAM systems employ a variety of spline types, spline representations, and curve design algorithms. The IGES (initial graphic exchange specification) was designed to enable interchange of the more commonly used spline types among CAD/CAM systems, independent of the design algorithms originally used to create them. IGES supports parametric cubic splines through a piecewise polynomial representation. This paper describes the design considerations leading to the interchange common spline curve types. A short introduction to splines and spline representations is included.     

Book Reviews

Chasen and Dow's text is a collection of selection guides for computer-aided design and manufacturing systems. Approaching CAD/CAM evaluation with a highly mechanical, "hand-holding" okbook of forms, checklists, and timetables the book appears geared toward nontechnical managers. Readers looking for a discussion of particular CAD/ CAM systems, trends, or technical information should look elsewhere (the Proceedings of the Design Automation Conference, for example).     

Guest editorial

Attention has recently focused on improving the information and knowledge flow between design and manufacturing. Interfacing Computer Aided Design (CAD) with Computer Aided Manufacturing (CAM) systems has helped this information flow while also improving both processes. Once CAD and CAM systems were introduced the obvious next step to (1) decrease a product's time-to-market and its costs, while (2) increasing the product's quality, has been to utilize knowledge based system technology during both the design and the manufacturing phases of a product. Unfortunately, the knowledge based systems that we have developed have been designed as stand-alone components. These have been built using a variety of implementation philosophies, styles of reasoning and are deployed over distributed computing environments. The companies with large investments in design and manufacturing automation, as well as in expert system technology have come to realize that achieving the two goals stated above will require the integration of such diverse systems in ways that will allow their coordination and cooperation. This special issue of theJournal of Intelligent Manufacturing has brought together reports of recent research whose goal was this type of integration.     

The 3D geometry modelling system (GEMO)

The Geometry Modelling System (GEMO), developed at Dresden University of Technology, covers the area of definition and manipulation of geometrical objects with regard to a further processing in a CAD/CAM system. The programming system GEMO has been designed modularly. The implemented algorithms are based on analytic and constructive geometrical methods. All modules have clearly defined interfaces, permitting a direct integration in CAD/CAM systems. Implementations for PCs and 32-bit computers are now available.     

Adding draft angles on mechanical components containing constant radius blending surfaces

The automation of mould design and manufacturing using computer-aided design and computer-aided manufacturing (CAD/CAM) draws the attention of many researchers. However, little attention is given to the automation of draft angles addition process. Draft angle is an important feature that facilitates the ejection of moulded parts. Existing algorithms for draft angles addition are still having limitations, especially for geometry with blending surfaces. A new approach for draft angles addition is introduced. It reduces the workload of users by automatically producing inclination on surfaces that require draft angles.     

BOM—致性维护

BOM是企业里不同部门，不同流程间传递数据的基本形式，由于企业内各部门的需求不一样，为满足不同的需求，企业内存在的众多的BOM形式，这些形式的存在阻碍了企业信息的有效传递，并可能导致数据不一致，文中给出部件关系，部件约束，以及部件配置等基本概念的形式化定义，并在此基础上给出BOM的一种柔性的定义，该形式化定义可有效地减少BOM的数理与种类，虽然此定义以制造业为基础，然而只有稍加推广，便可适用于其它领域，最后，针对BOM可能出现不一致的几种情况进行分析，并相应地提出一些算法。     

A proposal for CAD/CAM interface with expert systems

In the computer-integrated manufacturing (CIM) environment, the key technologies, CAD and CAM, should be fully integrated with high operability. It is claimed, however, that CAD and CAM have so far been developed independently. Although much effort has been made to integrate CAD and CAM, this reality is far from completion.

Therefore, to establish a CAD/CAM interface with higher integration, the concept of a computer-aided drafting procedure with expert systems has been proposed on the basis of analysis of the information explicitly and implicity described on the part drawing, and also of the required knowledge of the designer to produce the part drawing. The CAD/CAM interface proposed here is available for producing not only the part drawing but also the process plan for the corresponding part, by effectively utilizing the knowledge of the expert. A prototype CAD/CAM interface deals with axi-symmetrical rotational parts implemented on a workstation.     

Growth, crisis and future of the factory

The process of industrialization in the 19th century was coupled with the existence of the factory. The organization of the work within factories through the combination of manual and mechanical activities led to a substantial productivity increase and a significant improvement in living standards. The satisfaction of basic needs and consumer demands led initially to the refinement of products and production processes; while at a later stage they contributed to the crisis of the factory. Presumably a new period of growth for the factory starts due to the thrust of innovation in the information technology. The key element of the future production renewal is the computer integrated and flexible automated factory of the future, which provides a continuous production flow and ties together energy, materials and information. Substantial parts of the computer integrated production are communication networks, intelligent generation systems, computer-aided design (CAD), computer-aided planning (CAP), computer-aided manufacturing (CAM), computer-aided quality control (CAQ) and stimulation systems. These combine intelligent machine-tools, intelligent robots, intelligent assembly machines, intelligent inspection machines and intelligent means of transportation within the factory of the future. The artificial intelligence and the possibility of remote control due to the developments in the information technology are the prerequisites for the setting-up of new production schemes. Next to the central organized factories, new decentralized production structures can be developed which would make possible drastic changes in the social life.     

A traceability information model for CNC manufacturing

This paper proposes an information model for tracing CNC manufacturing operations. The objective of the model is to assure that traceability data is comprehensive and available for every CNC machined product, independent of the relationship between the subcontractor and the contractor. The prominent feature of the model is a link between CNC report data for a product instance, the CAD design and the CAM data. This link enables users to browse the traceability data and understand the relationships between the manufacturing process, the CAD design and the CAM data. The link is independent of the systems used to build the CAD and CAM data, and allows the users to be sure the manufactured product contains the required characteristics. Then if a product instance fails, this linkage will make possible to analyze the trace data and identify any exceptions or unusual conditions in the manufacturing process.     

Surgical and interventional robotics: part III [Tutorial]

Part I of this tutorial described two broad paradigms of interventional assistance: surgical computer-aided design (CAD)/computer-aided manufacturing (CAM) and surgical assistance. Part II focused on the underlying concepts of surgical CAD/CAM, with a particular emphasis on percutaneous procedures. This final installment of our three-part tutorial series discusses surgical assistance. In this section, we introduce the basic concepts of a surgical workstation and briefly review several core robotic technologies used in surgicalworkstations