Quantitative evaluation of product disassembly for recycling

This paper presents a method for evaluating the ease-of-disassembly of products. Its primary use is in designing products for recycling, but it also facilitates consideration of servicing and maintenance, and making environmentally-related decisions. The method is developed and discussed in the context of relatively small products that can be disassembled by a seated person using hand-held tools. The evaluation procedure is centered around a spreadsheet-like chart and uses a catalog of task difficulty scores. The scores were derived from work-measurement analyses of standard disassembly tasks, and provide a means of identifying weaknesses in the design and comparing alternatives quantitatively. The structure of the evaluation chart and the derivation of difficulty scores are explained, followed by a demonstration of analyzing a computer central processing unit. The limitations of the method and future extensions are outlined.     

Automated manufacturability analysis: A survey

In the market-place of the 21st century, there is no place for traditional over-the-wall communications between design and manufacturing. In order to design it right the very first time, designers must ensure that their products are both functional and easy to manufacture. Software tools have had some successes in reducing the barriers between design and manufacturing. Manufacturability analysis systems are emerging as one such tool — enabling identification of potential manufacturing problems during the design phase and providing suggestions to designers on how to eliminate them.In this paper, we provide a survey of current state-of-the-art automated manufacturability analysis. We present the historical context in which this area has emerged and outline characteristics to compare and classify various systems. We describe the two dominant approaches to automated manufacturability analysis and overview representative systems based on their application domain. We describe support tools that enhance the effectiveness of manufacturability analysis systems. Finally, we attempt to expose some of the existing research challenges and future directions.     

Modelling engineering change management in a new product development supply chain

The changes within a new product development (NPD) process are handled differently depending on the stage of the project. The changes during the initial stages of the project are addressed by design iterations, while the changes after the product design is complete are addressed using a formal engineering change management (ECM) process. The ECM process is a complex process, especially under a collaborative environment, where various independent entities work together for a common cause of product development. The interactions between the NPD and ECM processes have rarely been investigated in the research community. In this paper, we attempt to study the interactions between the various NPD and ECM process parameters by modelling the processes and simulated the model to understand the parameter interactions. The organisations in a supply chain have been characterised based on their interactions with the original equipment manufacturer (OEM) during the NPD process. The organisation process templates representing the NPD and ECM processes of each type of organisation in the supply chain have been modelled. The templates have been used to develop a simulation model representing the NPD and ECM processes for a supply chain. The process variables, such as processing rates, resources, resource composition, resource allocation priority, processing quality and phase overlap, have been included in the model. The results indicate that most of the variables and interactions among the variables have a significant influence on the NPD lead time. By identifying the status of?the NPD process, the decision-makers can use these results to develop appropriate management policies to govern their product development projects.     

面向并行工程的知识管理研究

知识经济和大规模定制等概念的提出,使得企业把知识财富作为获得竞争优势的战略要素来看待,企业知识管理由此受到学术界和企业界的共同关注。知识管理方法和工具集同并行工程现有方法和工具集的结合,产生了一个新的研究和应用领域,作者在跟踪国外研究和并行工程实践经验的基础上,对这一新兴领域的基本内容,实施方法和关键技术作了初步的讨论,以期引起国内学术界和企业界对该领域的关注,促进我国企业形成自己的核心竞争能力。     

Managing the integrity of design data generated by multiple applications: The principle of patching

The purpose of this work is to develop automatic methods of semantic integrity maintenance, in support of concurrent engineering. Semantic integrity relations in any final engineering design are built up incrementally, through the use of different computer applications. Here, the structure of these integrity relations are formalised for representation within a database. When changes to a design have to be made, they can invalidate integrity relations in other parts of the design. Formal methods are defined for identifying what data and integrity relations are invalidated by any change. Methods for making changes that minimise re-design are described and formalised. Opportunities for using semantic integrity to assess progress on a design are reviewed.Research supported by NSF grant IRI-9319982.     

A network approach to parametric design integration

This article presents a method for the integration of multiple computing processes used in design and design assessment for a parametric design problem. The method is based on a representation in which the processes are regarded as performing transformations between model states representing attributes of the designed artefact. A classification of attributes and of transformations is presented. The sequences of transformations and model states are modelled using Petri nets, and these models are used as a basis for the development of a computer-based controller that manages the interprocess interaction. The controller directs the concurrent and sequential operation of a number of computing processes operating on different workstations in a network. These processes include geometric modelling and a variety of design analysis actions that exchange data with each other in the optimum design of parametric parts. The example of an automotive crankshaft design is given.     

面向制造的设计系统中的可制造性评价方法与应用

对面向制造的设计系统中的可制造评价进行了深入地探讨，     

Case studies of coordination activities and problems in collaborative design

The design and engineering of large, complex electromechanical artifacts for use in space requires the integration of many engineering groups, spread across the components of the artifact and across the customer and suppliers. And within each engineering group there is a need to integrate the many diverse skills required, such as electrical, mechanical, thermal, software and materials. This paper describes the results of a study conducted from the Summer of1992 through the Fall of1993 at a medium sized aerospace company. The study had two goals. The first goal was to identify project delays that were due to poor coordination and integration. The second goal was to identify the activities which occupy engineers at the company and to rank the activities by the level of frustration and wasted effort encountered in performing them. The first goal was accomplished by studying25 problem cases, compiled and classified into six problem categories: information acquisition (24% of cases), information access (32% of cases), knowledge access (4% of cases), decision interdependence (8% of cases), activity management (12% of cases) and agent access (16% of cases). The delays associated with information acquisition, information access and knowledge access range from 1 day to as much as a year; they range from 1 day to a week for the other categories. The second goal, to identify the activities which occupy engineers and to rank the activities by the frustration and wasted effort encountered, was accomplished by conducting a survey, circulated to 30 engineers across five different departments. The participants were required to track the time spent in seven different activities over an actual 5 day week. They also estimated the time they would spend on these activities in a typical week on a percentage basis. The percentages of time spent were: information gathering (13.7%—actual; 12.2%—typical), problem, solving/thinking (28.0%—actual; 29.8%—typical), documentation (23.5%—actual; 19.5%—typical), planning (7.8%—actual; 8.5%—typical), negotiating (7.6%—actual; 9.8%—typical), support and consulting (17.1%—actual; 18.1%—typical) and other (2.3%—actual; 2.1%—typical). The participants also rated the activities from 1 (most frustrating) to 7 (least frustrating). The average scores, beginning with the most frustrating, were: 3.33-information gathering, 3.48-negotiation, 3.56-documentation, 3.67-support/consulting, 3.9-planning, 4.52-problem solving/thinking and 6.67-other.     

Information hiding in product development: the design churn effect

Execution of a complex product development project is facilitated through its decomposition into an interrelated set of localized development tasks. When a local task is completed, its output is integrated through an iterative cycle of system-wide integration activities. Integration is often accompanied by inadvertent information hiding due to the asynchronous information exchanges. We show that information hiding leads to persistent recurrence of problems (termed the design churn effect) such that progress oscillates between being on schedule and falling behind. The oscillatory nature of the PD process confounds progress measurement and makes it difficult to judge whether the project is on schedule or slipping. We develop a dynamic model of work transformation to derive conditions under which churn is observed as an unintended consequence of information hiding due to local and system task decomposition. We illustrate these conditions with a case example from an automotive development project and discuss strategies to mitigate design churn.

A method for imprecision management in complex product development

Managing uncertainty levels is important for organizations carrying out complex product development processes since it fosters design process improvements and optimization. Among the different uncertainties, design imprecision is known to represent uncertainty in decision-making that typically triggers changes to the value assigned to design variables during the early stages of the development process. This paper presents a method aiming to support large organizations understanding, quantifying and communicating this type of uncertainty. The imprecision management method that is proposed relies on five main steps: collection of historical records of change, time evolution reconstruction, statistical characterization of the typical levels of imprecision that should be expected, communication to new projects and continuous knowledge update. In addition, we present results from a case-study performed at Rolls–Royce that tested the method’s applicability in practice. The study shed light to interesting empirical findings about the typical level of imprecision in design variables and its evolution during real product development projects. The results from this initial evaluation suggest that the method provides useful support for design process management and thus has industrial value.     

Nippondenso Co. Ltd: A case study of strategic product design

Nippondenso Co. Ltd (NDCL) is Japan's foremost manufacturer of automotive components. Over the past twenty-five years it has developed a variety of approaches to automating the assembly of products in order to meet the high-variety, just-in-time production requirements of its customers, notably Toyota. The approach evolved by NDCL is to design the product intelligently and to make massive use of the simplest automation technology possible consistent with the technical challenges of the product and its production strategy. The result is the capability to manufacture products with considerable model mix at high volume, with little or no changeover time between models. This is essentially a technological response to a business environment challenge.In pursuit of this strategy, NDCL has categorized the problems of assembly automation into distinct classes, identified applicable solutions for each class, and successively attacked and solved increasingly difficult problems. This paper describes this strategy, gives examples of its evolution, and indicates how NDCL has managed production technology, notably robots, as part of the overall attack. NDCL's approaches to concurrent engineering (CE) and new product risk management are also described. The paper is based both on seven personal visits to NDCL during the period 1974 to 1991, which included extensive interviews with NDCL engineers and managers and plant tours, and on papers published by NDCL and interviews with their authors.     

产品开发过程管理系统

分析了PDM系统对产品开发过程管理的基本功能和不足,提出了一种集成产品数据管理和开发过程管理的工作流管理系统,提出了一种以过程活动为核心,集成了产品结构,组织,资源,成本和时间等视图的集成化产品开发过程模型。针对此模型,设计并实现了一个集成工作流建模,工作流执行和产品数据管理的产品开发过程管理系统。     

并行工程中的产品开发过程规划方法研究

从产品开发各过程单元之间的依赖关节出发,详细研究了识别产品开发中的耦合过程集合的有效方法。提出了以耦合过程集合识别为基础的产品开发过程规划策略,为并行工程的实施提供了基础。     

A method for evaluating functional content in mechatronic systems using optimisation

This paper presents a method to support designers and product planners in determining the functionalities that should be implemented in a product and those that should not. The proposed method identifies the set of customer functions and technical implementations that maximise the potential product profit. The customer functions represent the functionality of the product, and the technical implementations are the hardware and software components needed to realise these functions. For industrial applications, the numbers of possible combinations of customer functions and technical implementations are extremely large. We present a mathematical framework that handles this problem. Furthermore, optimisation is employed to find the set of customer functions that will maximise profit when subjected to a restricted development budget in order to find the best possible business case. The method was evaluated on an industrial case study of active safety systems performed at Volvo Cars. Based on this case study, the proposed method shows a substantial potential compared to the methods presently used.     

Producibility Analysis Using Metrics Based on Physical Process Models

This paper presents an approach to evaluating producibility which is intended to enhance the ability of engineers to quickly design low-cost and high-quality parts. We divide all production processes into two categories: trajectory-dominated processes in which a generic tool is moved in a trajectory to form the part shape, and process-physics-dominated processes in which shaped tools are used to form similarly shaped parts. We focus on process-physics-dominated processes and on producibility problems that arise because of part shape. We argue that for these processes the currently popular approach of representing parts as collections of geometric features may be inappropriate for evaluating producibility. We propose an alternative approach and representation. Our approach consists of first identifying the different failure modes of the process and then defining producibility metrics corresponding to the likelihood of encountering each failure mode. This set of metrics is used to represent the degree to which a part is easily manufactured. Finally, we demonstrate this approach by developing a set of metrics for evaluating the producibility of aluminum extrusions. We use extrusions from the Boeing 777 to validate the metrics.     

A method for assessing the impact of product development on the company

Because of competitiveness, the problem of product and production system developments is becoming increasingly current. From the point of view of products and production systems, companies must have tools to redesign, analyse, choose and manage their developments. After analysing which tools and methods exist in the scientific literature, we present in this paper a general method for assessing the impact of product development on the company. This method can be applied for each criterion that the company wants to analyse (delay, cost, organization, resources, quality, etc); we choose here the delay criterion. The method features four steps. The first step aims to characterize the case study by representing it with generic parameters. The second step offers the construction of a matrix model (called a static model) in order to categorize the product developments. The third step proposes the construction of a Temporized Coloured Petri Net model (called a dynamic model) and the fourth step simulates this model in order to obtain the expected result: the assessment of impact of the product development. At the end of the paper, we propose a case study on a roller tapered bearing manufacturer-- the Timken company.     

Back to the future with CAD: its impact on product design and development

This paper briefly examines the history of the management and organisation of the product development cycle. It looks at some of the key factors that have affected product development, and how information technology through CAD may have opened the door to a simultaneous product design process that has more in common with ‘older’ craft-based methods than those developed in the recent industrial era.     

A methodology for planning experiments in robust product and process design

Robust design is an important method for improving product manufacturability and life, and for increasing manufacturing process stability and yield. In 1980 Genichi Taguchi introduced his approach to using statistically planned experiments in robust product and process design to U.S. industry. Since then, the robust design problem and Taguchi's approach to solving it has received much attention from product designers, manufacturers, statisticians and quality professionals. Although most agree on the importance of the robust design problem, controversy over some of the specific methods used to solve the problem has made this an active research area. Although the answers are not all in yet, the importance of the problem has led to development of a four-step methodology for implementing robust design. The steps are (1) formulate the problem by stating objectives and then listing and classifying product or process variables, (2) plan an experiment to study these variables, (3) identify improved settings of controllable variables from the experiment's results and (4) confirm the improvement in a small follow-up experiment. This paper presents a methodology for the problem formulation and experiment planning steps. We give practical guidelines for making key decisions in these two steps, including choice of response characteristics, and specification of interactions and test levels for variables. We describe how orthogonal arrays and interaction graphs can be used to simplify the process of planning an experiment. We also compare the experiment planning strategies we are recommending to those of Taguchi and to more traditional approaches.