Showing papers in "Robotics and Computer-integrated Manufacturing in 1999"

Product modularization for life cycle engineering

Abstract: Modular products consist of detachable modules, which can be manufactured, assembled, and serviced separately Some of the modules may be reusable, recyclable or re-manufacturable upon product retirement Thus, modular design can provide benefits to many aspects of product life cycle This paper presents an integrated modular design methodology for life cycle engineering The methodology consists of three phases: problem definition, interaction analysis and module formation The methodology identifies the factors related to the design objectives, relates these factors to design components through interaction analysis, and clusters components into modules Two case studies along with detailed analysis are provided to illustrate the methodology and the algorithms

Production planning and control for remanufacturing: a state-of-the-art survey

Abstract: Remanufacturing is rapidly emerging as an important form of waste prevention and environmentally conscious manufacturing. Firms are discovering it to be a profitable approach while at the same time enhancing their image as environmentally responsible, for a wide range of products. In this paper the characteristics of the remanufacturing environment are discussed first to distinguish this environment from other manufacturing environments. The production planning and control function of the remanufacturing firm is examined in this environment. The research in the various decision-making areas that comprise the production planning and control function is evaluated. There are many areas where the research is still scant. The lack of any overall integrated framework and models for the production planning and control function is noted. It is also pointed out that most firms are still grappling with these problems and do not have any formal mechanisms in place. There is a need to develop models and frameworks grounded in the problems and needs of these remanufacturing firms.

Product, process, and organizational design for remanufacture – an overview of research

Abstract: In this paper, an overview of research aimed to improve remanufacturing is given. Compared with recycling, the research efforts in the area of remanufacture seem to be less pervasive. Specifically, descriptive work that seeks to characterize the current state or future of remanufacture, and developmental work that seeks to improve product, process, and/or organizational aspects of remanufacture are presented. The review presented is intended to provide an overview of the types of work that exists in the field of remanufacture and to provide a useful starting point for researchers interested in exploring the area of remanufacturing in greater depth.

Application of a design-for-remanufacture framework to the selection of product life-cycle fastening and joining methods

Abstract: This paper describes efforts towards product design that facilitates remanufacture. Insights on how to design products for ease of remanufacture were obtained from literature and collaboration with remanufacturers. The most essential aspect of design for remanufacture was found to conflict with other design-for-x methodologies, such as design for assembly and design for recycling. Design for remanufacture was therefore viewed in the context of other life-cycle domains, specifically manufacture and assembly, maintenance, and scrap-material recycling. Since fastening and joining issues are common to all these domains, a framework that evaluates the effect of joint design on each of these life-cycle stages was developed. This framework estimates the cost of remanufacture relative to other life-cycle costs determined by the joint design, and was applied to case studies of joints that did not facilitate remanufacture.

Disassembly analysis through time estimation and other metrics

Abstract: This paper examines the problem of assessing product ease of disassembly for recycling in light of the broader issue of manufacturability evaluation. The disassembly time estimation method outlined here is shown to provide one of several needed metrics for use during product design. Moreover, the ability to estimate process time provides the foundation upon which other metrics can be developed. The evaluation based on disassembly time is demonstrated on an electric drill example, and the difficulties associated with generating other disassemblability metrics are discussed.

A science-based approach to product design theory Part I: formulation and formalization of design process

Abstract: This paper, first of the two parts series, addresses a science-based approach to the study of design processes. Design process is an evolving process that begins with design requirements and ends with product descriptions. A general design governing equation is proposed to characterize the design process. We also proposed a design process model that embodies synthesis and evaluation processes, design problem redefinition process, and design decomposition process. The basis of the design process model is primitive design which is formalized as a six-step process. Any design problem can be decomposed into primitive designs. Utilizing the design representation scheme we established using set theory, the design process is mathematically formulated and formalized. The detailed explanations are provided to illustrate the design governing equation, the design process model and the mathematical formulation.

Macro level product development using design for modularity

Abstract: Modular design is an engineering methodology that will organize and structure a complex product, process or system into a set of distinct sub-systems and components that may be developed independently of each other and then assembled together. Modular design aims at identifying independent and standard units that could be used to create a variety of products. A structured methodology is proposed for identifying components that can be developed in parallel. In the proposed methodology the needs and product functional requirements are first established. The product is then decomposed based on its functional and physical characteristics. Next, a similarity index is introduced to measure the associativity between the basic components. Finally, a clustering technique is used to integrate the basic components into design modules based on their similarity index.

Selective disassembly for virtual prototyping as applied to de-manufacturing

Abstract: Selective disassembly involves separating a selected set of components from an assembly. Applications for selective disassembly include de-manufacturing (maintenance and recycling), and assembling. This paper presents a new methodology for performing design for selective disassembly analysis on the CAD model of an assembly. The methodology involves the following three steps: (i) identifying the components to be selectively disassembled for de-manufacturing by a software program or designer, (ii) determining an optimal (e.g. minimal cost) disassembly sequence for the selected components that involves a computationally efficient two-level reduction procedure: (a) the determination of a set of sequences with an objective of minimal component removals via a wave propagation approach that topologically order components in an assembly for selective disassembly, and (b) the evaluation of resulting sequences based on an objective function (e.g. minimal cost) to identify an optimal sequence, and (iii) Performing disassembly design decisions based on the evaluated optimal sequence. Preliminary implementation results of the selective disassembly methodology in sequencing and disassembly cost evaluation, and application of the selective disassembly technique for de-manufacturing assessment are presented.

Feature-based process planning for environmentally conscious machining – Part 1: microplanning

Abstract: Process planning in environmentally conscious machining involves a multi-objective analysis of manufacturing dimensions that include production rate, quality, process energy and mass of waste streams generated by the process. While there has been a body of work developed in life cycle analysis, one of the critical issues limiting environmental analyses is the material and geometric complexity of engineered components. In this paper a formalized approach towards integrating environmental factors in process planning is presented, which incrementally evaluates part designs through an aggregation of features. Process planning is divided into two phases, micro and macroplanning. In microplanning, process, parameters, tooling and cutting fluids are selected for the individual features, while in macroplanning interactions between features are examined. Microplanning is the focus of this paper where predictive process models are used to obtain process level inventory of process energy, machining time, mass of waste streams (primary scrap and secondary catalysts) and quality parameters. The mass of waste streams are then evaluated for their environmental impact based on a health hazard scoring index. The Microplanning algorithm integrates these dimensions in an optimization framework to make robust process planning decisions at the feature level. A case study of a machined part is presented to illustrate the microplanning methodology.

A hybrid-graph approach for automated setup planning in CAPP

Abstract: In this paper, a systematic approach for automated setup planning in CAPP is introduced. The concept of “hybrid graph”, which can be transferred into directed graph by changing any two-way edge into one-way edge, is introduced. The specified graph theory is effectively used in setup planning. Tolerance relations are used as critical constraints for setup planning. Comprehensive principles are explored and summarized for setup planning. The hybrid-graph theory, accompanied by matrix theory, is used to aid computerizing these principles. An example is illustrated to demonstrate the algorithm.

Web-based product and process data modelling in concurrent “design for X”

Abstract: This paper is concerned with employing the web technology for concurrent modelling of product and process data on the Internet. This is one of the essential tasks of an attempt to develop a generic web-based Design for X (DFX) shell which can be tailored or extended to develop and apply a variety of DFX tools easily, quickly and consistently. The emphasis is placed on the use of a number of formal but pragmatic constructs. Bills of materials are used to describe and analyse the overall product structure and characteristics. Flow process charts are used to describe and analyse the overall process structure and characteristics. Standard operation process charts are modified to describe and analyse the interactions between the overall product and process structures. These concepts have already been widely used by practitioners or at least are familiar to various personnel involved in product development. They are coded as reusable ActiveX components that can be easily deployed in the DFX shell.

Latest developments in CIM

Abstract: Manufacturing enterprises play an important role in improving the economic environment of a country. The economic environment of many developed countries is under threat from emerging industrialised countries. Today, the capability of producing high quality products with shorter delivery times and the ability to produce according to the diverse customer requirements have become the characteristics required of order-qualifiers for manufacturing industries. Hence, application of intelligent manufacturing systems and computer integrated manufacturing (CIM) has become the necessity to overcome the above issues while retaining the employment level and revenue of a country in today's highly competitive global market. With the developments taking place in CIM and its related technologies, the application of CIM in manufacturing enterprises has become a reality. This paper focuses on latest research developments in CIM and a new CIM wheel proposed to satisfy the emerging technological application of virtual enterprises.

A science-based approach to product design theory Part II: formulation of design requirements and products

Abstract: The Design Process begins with design requirements and ends with product descriptions. The design requirements include both structural and performance aspects. The product descriptions deal with the structural aspect of the design requirements while the product performances describe the performance aspect of design requirements. In this part of the paper, a set theory-based representation scheme is proposed to represent design objects in the design process, including design requirements, product descriptions, and product performances. This representation scheme can represent the design objects that evolve in dynamic design processes. The entire mathematical scheme is defined based on structural and behavioral properties. Within one uniform scheme, the design objects are represented at different levels of complexity and abstraction. Several examples are included to explain the scheme and its mathematical formulations. The proposed scheme can be used for science-based studies of product design.

Simulation of surface generated in abrasive flow machining process

Abstract: For the control of abrasive flow machining (AFM) process, it is important to understand the mechanics of generation of its surface profile. This paper describes the analysis and simulation of profile of finished surface and material removal by the interaction of abrasive grains with workpiece. The abrasive grains are randomly distributed in media depending upon their percentage concentration and mesh size. The results predicted from simulation and obtained from response surface analysis (or experiments) are compared to explain the relative importance of AFM parameters. The generated surface profile and material removal are the function of number of cycles, percentage concentration and mesh size of abrasives, reduction ratio and extrusion pressure applied.

Feature based process planning in environmentally conscious machining – Part 2: macroplanning

Abstract: A second aspect of integrating environmental factors into manufacturing process planning is macroplanning, where the inter-relationships between features are accounted for. While micro-planning results in a process plan which is the aggregation of feature-level optimal plans, the aggregation of microplans does not necessarily result in a globally feasible process plan for a given part. Macro-planning issues which have significant environmental impact include process sequence selection for intersecting or nested features and feature clustering based on common setups and catalysts (tools and cutting fluids). These macro-planning issues influence both batch-level routing and scheduling decisions in a job shop and resource allocation, line balancing and facility planning decisions in a transfer line. Building upon the feature-level optimization presented in Part 1, case studies of feature interactions will be presented and an overall sequencing algorithm will be outlined. Both the micro and macro-planning schemes are integrated with a solid modeling environment to serve as a platform for analyzing incremental component design changes.

Flexible robot-based disassembly cell for obsolete TV-sets and monitors

Abstract: Disassembly is a developing field of application for automated components for processing electronic waste. The reasons behind its rapid development are changing legislation in favor of environmental protection because of a globally increasing amount of obsolete electronic products and growing public awareness of environmental problems. A prototype of a flexible robot based disassembly cell for obsolete TV-sets and monitors has been developed at PRIELOG Logistik GmbH and is currently being adapted to the demands of industry. Main parts of this system are a disassembly robot, a handling robot, an intelligent vision system as well as software for highly flexible online planning and control of the disassembly process. A detailed description of the disassembly cell and first results of industrial adaptation are introduced in this work. The results lead to optimized reactive planning algorithms as well as improved sensor systems and the usage of universal and flexible disassembly tools and fixtures.

Cost-effective design for injection molding

Abstract: It is commonly agreed that a large proportion of the ultimate product cost is determined at product design stage. Therefore, a cost-effective design cannot be obtained unless all cost issues are resolved at early design stage. Therefore, instead of performing cost estimation after design, research presented in this paper aims to provide on-line cost evaluation and advisory to help product designers avoid cost-ineffective design. The objective can be obtained by (1) identifying factors that might affect product cost at each product design stage, (2) developing a design for cost effectiveness methodology that accommodates the concepts of concurrent engineering, and (3) developing a computer-based design for cost effectiveness system based on the proposed methodology. In this research, we focus on injection molding product design due to the advantages of injection molding process, such as high production rates, excellent quality and accuracy of the parts, and very long mold life. This paper first reviews and characterizes the conventional molding product development process with an emphasis on the identification of cost factors. Based on the results of process characterization, a cost model is developed, which depicts the relationships between cost factors and product development activities, as well as their relationships with product geometry. According to the product life cycle activities and the cost model, a design for cost effectiveness process is proposed. The process and the cost model are then employed for the development of a computer-based product design for cost effectiveness as one of the module of an integrated design for injection molding environment.

A Procedure for Building Product Models

Abstract: This article presents a procedure for building product models to support the specification processes dealing with sales, design of product variants and production preparation. The procedure includes, as the first phase, an analysis and redesign of the business processes, which are to be supported with product models. The next phase includes an analysis of the product assortment, and the set up of a so-called product master. Finally the product model is designed and implemented using object oriented modelling. The procedure is developed in order to ensure that the product models constructed are fit for the business processes they support, and properly structured and documented, in order to facilitate that the systems can be maintained continually and further developed. The research has been carried out at the Centre for Industrialisation of Engineering, Department of Manufacturing Engineering, Technical University of Denmark.

An integrated CSCW architecture for integrated product/process design and development

Abstract: Computer Supported Collaborative Work (CSCW) is increasingly being used by engineering design teams to reach a consensus on a range of design issues. CSCW systems are designed to increase the effectiveness of decision-makers by facilitating information exchange, retrieval, sharing and use. They encourage interactive information exchange and have the potential to reduce diseconomies associated with design activities, member dominance, social pressure, inhibition of expression, and other difficulties encountered by project teams. The use of CSCW is expected to have a favorable impact on the group decision-making process and the quality of the resulting decision. In this paper, a general CSCW architecture has been developed to support integrated product/process design and development will be presented. The architecture has been tested extensively on a representative industrial problem. The case study and evaluation of the architecture will also be discussed in this paper. The integrated architecture will facilitate information access, sharing, and analysis among design teams members using the open World Wide Web platforms and resources to make product/process decisions.

On-line predictive model for disassembly process planning adaptation

Abstract: This paper presents an on-line predictive model for disassembly process adaptation. The prediction enables a planner to adapt the process plan based on the condition of the product (e.g., degree of rustiness, deformation) during process execution. This model tries to correlate the product physical condition, used as an explanatory variable, with the component value and disassembly cost, the response variables. The core of the approach is based on an inference engine that used a kernel regression. A simple methodology for integrating the predictive planner in a disassembly system is presented and exemplified by a case study of the disassembly of a ratio.

Job grouping in surface mounted component printing

Abstract: The arrangement of operations in a production line for mounting the surface components on a printed circuit board is discussed. The production program includes a wide range of different products, which causes frequent set-up operations. The overall efficiency of the production line depends heavily on how the printing operations are organized. Set-ups cause delays which can be cut down by selecting carefully the feeders for the components and by solving a suitable sequence for the products. We describe an integrated production management system for job grouping. The system utilizes approximate algorithms for minimizing the number of component switching instants. A discussion of the exact minimization by using mathematical 0/1 integer programming approach is also given. The revision of the production management system has had a major impact on the productivity, and an increase of ca. 58% in the number of component insertions per hour is observed.

The NEXUS open system for integrating robotic software

Abstract: In this paper a framework for constructing flexible, robust and efficient software applications for robots is described. The basic concepts needed to integrate complex, multidisciplinary robot software architectures are identified, and the methods to achieve them are taken from different areas of research (programming languages, network communication systems, real-time systems, etc.). The result is an open software system called NEXUS which includes the basic characteristics needed for the integration of very different software modules, minimizing the effort of integration and maximizing the reusability, efficiency and robustness of the resulting software applications. This software has proven to be a basis for more sophisticated tools that help in reducing the cost of modifications to and the complexity of multidisciplinary projects, allowing highly structured and reusable designs to be implemented. Although it has been currently implemented for mobile robots, it is a sufficiently generic framework suitable for use in other control systems.

Evaluations of operational control rules in scheduling a flexible manufacturing system

Abstract: In this paper, computer simulation is used to evaluate the effects of various control rules on the performance of a flexible manufacturing system (FMS) operating under different manufacturing environment. Alternative routings are available, if the operation of a part can be performed by more than one machine. Three control rules, namely, dynamic alternative routings, planned alternative routings, and no alternative routings, are proposed to control the selection of alternative routings for each part. The effects of the universal loading station and also those of the dedicated loading station are investigated. In addition, the impact of buffer existence on the system’s performance is also examined by considering machines with and without local buffers. The effects of changing production ratios of different part types on the performance of various operational control rules are also investigated. Moreover, the effects of system having machine breakdown are also discussed. The simulation results indicate that the FMS with dedicated loading stations outperforms the FMS with universal loading stations in all aspects. The dynamic alternative routings generally produces the best results in system performance if the universal loading station is provided. The planned alternative routings generally gives the best system performance when both the dedicated loading stations and local buffers are available. The no alternative routings usually remains at the bottom of the rank, occasionally with some exceptions. Problems in actual implementation are also highlighted.

An object-oriented constraints-based system for concurrent product development

Abstract: This research work aims to develop an intelligent constraint-based system that enables designers to consider at the early stages of the design process all activities associated with product’s life cycle. One of the most important aspects of these activities is the evaluation and optimisation of manufacturing processes that require various type of information from the different aspects of product’s life cycle. This research article discusses the development of a prototype system for manufacturing process optimisation using a combination of both mathematical methods and constraint-programming techniques. This approach enables designers to evaluate and optimise feasible manufacturing processes in a consistent manner as early as possible during the design process. This helps in avoiding unexpected design iterations that wastage a great amount of time and effort, leading to longer lead-time. The development process has passed through the five major stages: Firstly, an intelligent constraint-based design system for concurrent product and process design has been developed. Secondly, a manufacturing process optimisation module has been constructed. Thirdly, the product features, processes, cost, time and constraints to be used for carrying out various design tasks has been represented in the format of constraints, frames, objects, and rules. Fourthly, the process optimisation and evaluation rules for the selection of feasible processes for complex features, and finally, the information management system that ensures consistency in information exchange and decision making activities have been developed.

Position control and repeatability of a pneumatic rodless cylinder system for continuous positioning

Abstract: Pneumatic cylinder systems have the potential to provide high output power to weight and size ratios at a relatively low cost. However, they are mainly employed in open-loop control applications where positioning repeatability is not of great importance. In this paper the repeatability of a pneumatic rodless cylinder system under closed-loop PD control is examined for its potential use in robotic applications. Our analysis shows that the linearized continuous time dynamics is dependent on the trimmed and operating conditions. This can cause positioning problems when a controller is designed based upon the transfer function obtained at a particular trimmed point. Furthermore, there are uncertainties associated with the dynamics which can lead to precision errors in both transient and steady-state responses. Due to these complexities, a pragmatic gain tuning methodology is proposed to achieve satisfactory nominal transient response characteristics over the range of loading requirements. With this scheme, it is suggested that the performance of the conventional controller be evaluated in terms of its repeatability. The repeatability of the system under different start–stop positions and loading conditions is experimentally found to be less than ±0.3 mm. This repeatability value is within typical industrial requirements.

An integrated product and process development methodology: Concept formulation☆

Abstract: Life cycle engineering, or integrated product and process development (IPPD), is a new trend of research and application in industry and academia. In our previous work, a generic framework was proposed to provide a means for an integrated consideration of the performance optimization issues in a product’s lifetime. Based on this generic framework, this paper proposes and presents an integrated product and process development methodology. Important concepts of the methodology are introduced, and an application procedure is provided to illustrate the systematic application of the methodology to real product and process development. Finally, we provide a brief report of our application of the methodology to personal computer development.

Reusability and multi-product development policies: a comparison of approaches in the automotive, motorcycle and earthmoving machinery industries

Abstract: In many industries, the compelling pressure on the replacement of existing products and the expansion of the breadth of product lines, are forcing firms to undertake a growing number of new product development (NPD) projects. The effectiveness of those efforts depends on how well the firm can exploit synergy in innovation. This entails to managing the sharing and transfer of knowledge to projects over time to maximise reusability of technological solutions. The paper investigates how firms have reshaped their NPD process to deal with the challenge of reusability and knowledge transfer in three related industries. Starting from a resource-based view of the innovation process it compares the multi-product development project practices diffused in these industries and identifies the factors which affect the choice of a given approach to reusability and knowledge transfer.

A hierarchic approach to production planning and scheduling of a flexible manufacturing system

Abstract: The paper deals with the problem of improving the machine utilization of a flexible manufacturing cell. Limited tool magazine space of the machines turns out to be a relevant bottleneck. A hierarchic approach for this problem is proposed. At the upper level, sets of parts that can be concurrently processed (batches) are determined. At the lower levels, batches are sequenced, linked, and scheduled. Methods taken from the literature are used for the solution of the latter subproblems, and an original mixed integer programming model is formulated to determine batches. The proposed methods are discussed on the basis of computational experience carried out on real instances.

Object-oriented specification of automated manufacturing systems

Abstract: The design of automated manufacturing systems (AMSs) requires an effective system specification that helps designers to deal with the changes in system requirements. This paper presents an object-oriented rule-based methodology for the specification of AMSs, which extends the capability of the existing object-oriented specification methods to support system integration and the explicit representation of control policies. The methodology is characterised by the use of rule-based modelling techniques to specify object behaviours in terms of processes. The application of the methodology is illustrated by the specification of a flexible manufacturing system.

A model-based approach to form tolerance evaluation using non-uniform rational B-splines

Abstract: Tolerance evaluation is critical to quality assurance in modern manufacturing. In contrast to traditional measurement which relies on specific hard gauges, coordinate measuring machines provide more flexibility for dimensional measurement and tolerance evaluations. To fully automate CMM inspection and tolerance evaluation, CAD/CMM integration is an important key. Although the subject of CAD-directed inspection has been widely researched, CAD model-based tolerance evaluation has received less attention. This paper presents a CAD model-based approach for evaluating general form tolerances using non-uniform rational B-splines. Unlike classical methods which construct substitute geometric features from the measurement data, this method evaluates form tolerances by comparing the measurement data with a nominal CAD model. Non-uniform rational B-spline (NURBS) is used to represent general form features since NURBS offers a common format for modeling different form features. With this unified database, a general best-fit algorithm is developed that can be applied to the evaluation of various form tolerances. Computer simulations have been performed on different form features to study the robustness and efficiency of the algorithm. Application to the profile analysis of turbo charger housing and turbine blade die segments are also presented.