A knowledge-based manufacturing and cost evaluation system for product design/re-design

Various research studies have concluded that most new design projects are actually re-design activities. This re-design may be for improvement or for reprovision of existing products. Most research efforts for providing computer tools for supporting conceptual or early design mainly concentrated on the design of new products. In practice manufacturing plans generated when an order was placed may quickly become out-dated as the manufacturing environment and constraints often change. It is therefore equally important to regenerate manufacturing plans and re-evaluate design every time a product is changed, re-designed or reordered. This project focuses on manufacturability analysis and provides re-design support for conceptual design of discrete single-piece mechanical parts with emphasis on machined processes. This limitation of implementing the prototype system for re-design activities is not a system design or methodology restriction. The condition has been imposed by the authors as a prelude to validating the system and its results. A novel hybrid approach using a combination of sequential flowchart logic and an expert system has been developed which uses a user-defined feature tree as the input for its analysis. The system allows the designer to estimate manufacturability according to criteria of time and cost, and also to explore different scenarios of parametric variation in the design. A case study has been presented to validate the system’s practicality and usefulness.     

A STEP AP224 agent-based early manufacturability assessment environment using XML

Early design assessment activities have a significant impact on reducing the cost of manufacture. The efficient utilisation of the product development time and the level of coordination of the early design activities between the major stakeholders are becoming key factors for success in manufacturing today. The paper reports on a new distributed early design manufacturability assessment methodology using collaborative autonomous agents. A product data model compliant with STEP AP224 and corresponding process and facility data models are proposed to support the decision-making process. XML was used as a medium for exchange of requests and information between design, manufacturing, and facility planning agents. A prototype Web-enabled system for rapid product manufacturability assessment in the extended enterprise has been developed using distributed multi-agent CORBA objects. The reported research is a step towards the development of a generic prototype tool for collaborative design evaluation and rapid assessment of the manufacturing feasibility and resource availability at different stages of the product development process.     

A concurrent manufacturing strategy for One-of-a-Kind Products with complicated sculptured surfaces

In this paper, we propose a computer-aided system for concurrently designing and manufacturing a customised or One-of-Kind Production (OKP) mould or die which has complicated sculptured surfaces. Considering the OKP production characteristics of high customisation and concurrent product development and production, we believe that the concurrent consideration of both the design and the manufacturability of a mould or a die would be necessary. This concurrence can be realised by providing timely manufacturability information feedback after a design is completed or a feature is modified or added in the design. The other problem is that the sculptured surface geometry model of a mould or a die does not contain any machining information. Hence we developed an intermediate data model for capturing manufacturing features when we are modelling the geometric form of a mould or a die. The system is based on CADDS5 which is a commercial CAD/CAM system. Two modules for data extraction, coverting and modelling as well as for manufacturability analysis have been developed and added to CADDS5. Using this computer-aided system; a designer can interrogate geometry and machining constraint information through a user friendly interface to avoid defects and inefficiency resulting from an earlier design, and can finalise the design by making quick incremental adjustments. The system has been implemented in a mould and die manufacturing company in China. This implementation leads to less rework and shorter lead time.     

基于特征Agent的并行设计系统

并行工程的主要目标之一在于对产品和过程进行并行评价,以缩短产品上市时间和降低产品成本。为了有效地在产品的设计过程中对产品的可制造性进行评价,本文提出了特征Ａｇｅｎｔ的概念。特征Ａｇｅｎｔ在自身状态或者外界环境发生相关变化时,实时地进行可制造性评价,给设计者提供反馈意见,从而有助于改善产品设计质量。在特征Ａｇｅｎｔ的基础上,文中介绍了一种由多Ａｇｅｎｔ构成的并行设计系统     

A manufacturability advisor for spun and rollformed sheet metal components

In today’s manufacturing scenario, accounting for manufacturability considerations at the product design stage is not an option but a necessity. When CAD/CAM tools are used to reduce design lead times, accounting for manufacturing process related considerations implicitly is often difficult. Availability of manufacturability advisor systems that analyze part geometry and other product related information for ease of manufacturing could be a solution to this problem. The purpose of a manufacturability assessment is to give feedback to the designer in order to make the product/process more effective. Present research is concerned with the development of an automated manufacturability advisor for sheet metal components. Unlike most of the work done in the past that concentrated on bending and other forming processes, present work deals with sheet metal components manufactured by two different processes, namely “spinning” and “rollforming”. Effectiveness of the proposed manufacturability advisor is demonstrated by taking the number of industrial parts as examples.     

面向可制造性评价的虚拟制造资源建模

虚拟制造是一种新的制造模式，可制造性评价是其关键技术之一，在虚拟制造中进行合理有效的可制造性评价具有重要意义。可制造性评价是与制造资源密切相关的，脱离具体的制造资源环境进行的可制造性评价没有任何意义。利用模糊分组技术和面向对象技术，建立了制造资源的功能单元和设备工艺能力双层模型，为后续的可制造性评价和成本评估提供信息支持。     

Developing a PDM/MRP integration framework to evaluate the influence of engineering change on inventory scrap cost

Quick response to market change has become a critical strategy for businesses in the global competitive environment. Since product design usually occupies a major time period of the product development process, shortening the time spent in the re-design stage has become an important issue for businesses. In this research, an environment integrating a PDM and an MRP application was proposed. By applying the concepts of Activity Based Costing (ABC), this environment can be used to support designers in a part re-design project to analyze inventory scrap costs. Using ARIS software, an eEPC model describing the re-design process in PDM, as well as the scrap cost analysis process, was developed. The major function of this integrated environment is to support the designer in making quick and proper decisions to reduce the inventory scrap cost of existing parts during the product re-design project.     

An ontology-based product design framework for manufacturability verification and knowledge reuse

To achieve efficient development of high-quality product, manufacturing constraints must be fully taken into account at the early design stage. However, designers lack in-depth knowledge of manufacturing and production. Many time-consuming iterations of design changes are required between designers and manufacturing engineers. In order to minimize this knowledge gap, this paper presents an ontology-based product design framework for manufacturability verification and knowledge reuse to support the sharing and reuse of design and manufacturing knowledge. It aims at providing advices and feedback of restraints of manufacturing processes to the designers during the design process. The proposed framework consists of three major layers which include a foundation layer, a domain layer, and an instance layer. We use the Web Ontology Language (OWL), a standard of ontology representation language, to formalize the foundation layer. It contains the core product model and the standard ISO 10303 AP224 application protocol. The domain layer comprises extensional concepts and relationships for design and manufacturing integration and a rule base for manufacturability verification, which is represented in Semantic Web Rule Language (SWRL). In the instance layer, an inference engine is developed based on ontology and rule inference. It provides recommendations of manufacturability. Two case studies are provided as application examples to demonstrate the effectiveness of the framework.     

Design for economic manufacture of small sheet metal parts

Arguments are presented for a consideration of the DEM of pressed parts on a basis of equipment and tooling used to produce the parts rather than consider a categorisation based on ‘type’ by industry. It is also suggested that a combination of both generative and variant techniques of process planning, in conjunction with a good classification system and data base, should be used by the designer to develop, store and retrieve the type of information used in cost-optimising the design of pressed parts. This paper outlines the elements of cost involved in the production of pressed parts and presents details of a computer-aided process planning system which will assist the designer to quickly obtain the information necessary to optimise the designs. Typical computer program inputs and outputs are presented together with rules that have emerged in pressing design to reduce the number of tooling stages required and therefore the component manufacturing cost.     

A heuristic algorithm for cell formation problems with consideration of multiple production factors

For the design of manufacturing cells, numerous mathematical models and various algorithms have been extensively investigated in the literature. However, most of the proposed models and algorithms have more or fewer drawbacks on the issues with real-life situations. In this paper, we propose a mathematical model that incorporates multiple key real-life production factors simultaneously, namely, production volume, batch size, alternative process routings and perfect coefficient of each routing, cell size, unit cost of intercell/intracell movements, and path coefficient of material flows. Then, to solve this NP-hard model, we develop a heuristic algorithm with three stages: (1) form the temporary machine group plan according to the alternative process routings of each part, (2) select the appropriate process routing of each part with respect to the over-all material movement cost, and (3) configure the regular manufacturing cells based on the appropriate process routing. A simple numerical example and an industrial case are used to test the computational performance of the proposed algorithm. The test results imply that it is useful for manufacturing cell design in both quality and speed.     

面向制造的零件设计：理论与实现

在传统生产模式中，设计与制造（或工艺）的脱节造成了设计返工多，加工难，效率低，成本高的弊病；面向制造的设计（DFM）同步考虑产品的功能和工艺要求，有利于设计决策在制造系统的全局趋于最优。在分析了主要的DFM方法论之后，本文着重阐述了计算机辅助DFM的优势及其实现方式，并对零件设计的DFM系统的体系结构进行了讨论。     

Design for pressure die casting—A DFM example

The designer makes many maufacturing decisions that influence the production cost and the quality of the product. It is therefore important to ensure that the designer has a good foundation for these decisions. When talking DFM, it is important to realise that there are large differences between companies in how product design and production are carried out. The objective of the present research is to investigate and to improve the communication flow between design and production for a selected area: pressure die casting. This area is characterised by many subcontracting producers, and design and production are therefore often placed at different geographic locations. This makes an efficient communication flow even more important and it also makes the communication interface more visible. This paper discusses how manufacturing considerations are made in different design situations and how information supporting tools should be formed accordingly. Results from an investigation of DFM in a number of pressure diecasting companies and companies that design products for pressure die casting are presented. The investigation focuses on the type, the detailing level and the accessibility of the part information passing from design to production and on the manufacturing guidelines and suggestions coming from production to design.     

基于图论的可重构制造系统重构策略

可重构制造系统(RMS)是针对零件族设计的既具有定制的柔性,又具有高生产率的制造系统。RMS通过重构来适应市场需求的变化。RMS的设计目标是基于重构条件下寻求制造系统在全生产周期内的系统成本最优。首先建立RMS的各生产周期成本模型、重构成本模型与全生产周期成本模型,构建RMS在各生产周期的组态有向图,利用Dijkstra算法与双向扫视算法求得RMS在各生产周期的最优成本组态与K-1个次优成本组态。根据所求得各生产周期的最优成本组态与K-1个次优成本组态,重构成本模型与全生产周期成本模型,计算上下生产周期各组态间的重构成本,并构建RMS全生产周期的重构策略有向图,再次利用Dijkstra算法与双向扫视算法求得 RMS全生产周期的最优重构策略与K-1个次优重构策略。最后用实例验证了方法的有效性与可行性。     

并行工程下基于特征的零件可制造性研究

结合并行工程的思想，对零件可制造性进行较详细的分析，提出并行工程环境下基于特征的可制造性分析方法，研究并建立基于特征的可制造性零件定义模型及评价体系，全面合理地对零件的可制造性进行评价和反馈，从而指导产品设计。最后以涡轮叶片榫头特征的可制造性分析为应用实例，说明该方法的有效性和实用性。     

面向制造的曲面设计系统

为了支持面向制造的曲面设计,提出了一个基于计算机辅助设计／计算机辅助制造系统的嵌人式计算平台,该计算平台主要包括约束信息建模和可制造性分析2个功能模块。通过对曲面可制造性判据的抽象,建立了应用信息模型,用于从曲面几何形状中提取制造约束信息。应用于曲面加工问题,给出了根据约束信息计算可行刀具方向的具体方法。面向模具零件分型曲面的设计,建立了可制造性分析工具。针对一个雕塑曲面零件设计实例,通过对模具分型方向和加工约束进行分析,给出了可行的分型曲面设计结果,验证了所提出的曲面可制造性分析方法的可行性。     

Developing manufacturing response models to predict the manufacturability of new modular products

Product developers usually rely on their experience and knowledge during the design process to generate manufacturable products that can fulfill the required functions. Product developers make various decisions during the course of developing a modular product that affect the functional, physical, and operational structures, which either enhance or reduce the manufacturability of the products. This paper proposes constructing manufacturing response models by modeling the behavior of the manufacturability as a response to the series of decisions made during the design process. The manufacturability response models are mathematical models used to relate the product manufacturability to the different metrics used to quantify the results of the design decisions made during the development life cycle. Decisions made during the design process includes specifying the product functionalities needed to meet customer needs, the physical components capable of delivering the required functionalities, and the manufacturing processes needed to produce the physical components. Manufacturing response models can be used by product developers to predict the effect of the decisions made during the course of developing a modular product on the final modular product manufacturability. Furthermore, this paper demonstrates the construction of the manufacturing response models and their usage in new product design by using an illustrative example.     

A knowledge-based design advisory system for collaborative design for micromanufacturing

The manufacture of microproducts differs from that of conventional products in many ways, not only in the sizes, but also in issues concerning the effects of material properties, tools, and manufacturing equipment. There was a need for a new design methodology and associated design tools to aid designers in assessing the design of their microproducts by considering new micromanufacturing capabilities and constraints. A knowledge-based design advisory system (DAS) was, therefore, developed in MASMICRO in which the knowledge-based system with dedicated assessment modules and knowledge representatives based on the ontology was created to implement the distributed design and manufacturing assessment for micromanufacturing. The modules address the assessment on geometrical features relating to manufacturability, manufacturing processes, selection of materials, tools, and machines, as well as manufacturing cost. The Microsoft C# programming language, ASP.NET web technology, Prolog, and Microsoft Access database were used to develop the DAS. The test on the DAS prototype system was found to provide an increase of design efficiency due to more efficient use of design and manufacturing knowledge and afforded a web-based collaborative design environment.     

基于STEP的制造资源能力建模及其应用研究

分析了并行工程对制造资源的需求特点,基于ＳＴＥＰ建立了制造资源能力模型,采用面向对象技术,建立了制造资源库和制造知识库;基于制造资源和制造知识,进行零件可制造性评价与反馈,从而指导产品设计。     

Development of a concurrent mold design system: a knowledge-based approach

This paper presents research that establishes a systematic methodology and knowledge base for an injection-molding mold design in a concurrent engineering environment. This methodology is, in general, analogous to the methods of design for manufacturing, and is, however, in collaboration with activities of molding product design and mold manufacturing process planning. The practical goal of this research is twofold: to develop a mold-development process that facilitates concurrent engineering-based practice and to develop a knowledge-based design aid for injection-molding mold design that accommodates manufacturability concerns, as well as requirements of products. The research approach includes (i) process modeling and reengineering for concurrent mold design, (ii) identification of functional requirements with a computer-based system, (iii) system framework design, and (iv) system modeling and implementation. The framework supports concurrent engineering based mold design by providing advisory tools that are able to resolve relevant issues at the early stages of mold design. The results of this research will facilitate the rationalization and automation of the mold development process, thus improving the efficiency and quality of, and reducing the cost of, mold development.     

并行工程下的面向制造的设计

结合并行工程的思想,对面向制造的设计进行了较详细的分析,指出面向制造的设计与并行工程的关系,提出了并行工程环境下面向制造的设计技术中存在的问题及对策,全面合理地对零件的面向制造的设计进行了评价,从而指导产品设计。