Andreas Dagman

A Multi-objective Tolerance Optimization Approach for Economic, Ecological, and Social Sustainability

Sustainable design requires simultaneous consideration of the economic, ecological, and social consequences of design decisions. The selection of dimensional tolerances and materials are two such decisions that have impacts in all three of these areas. This article presents an optimization framework along with generalized models for considering sustainability and understanding how different aspects of sustainability may trade off with one another. A mobile phone design is used as a case study to demonstrate the strengths of the approach when varying manufacturing tolerance and material choice, and the results include three-dimensional Pareto frontiers illustrating the design tradeoffs.

Tolerance optimisation considering economic and environmental sustainability

Sustainability is becoming increasingly important in the development of new product and production solutions, and the eco-design movement stresses the importance of environmental considerations in all design phases and activities. One such design activity in the embodiment design phase of product development is the specification of dimensional tolerances, where designers seek to ensure high functionality at low costs. A traditional approach to this decision-making process is to minimise economic losses to the manufacturer and the consumer through a process known as tolerance optimisation. This paper presents a new approach for tolerance optimisation that considers sustainability not only in the context of economic costs but also environmental impacts, which are shown to be significantly affected by manufacturing and product quality. This new framework is formulated as a bi-objective optimisation problem to minimise economic and environmental costs, and important modelling considerations for these two types of costs are outlined and discussed. The proposed approach is explored using two example cases of design assemblies, which demonstrate the trade-offs between economic and environmental design objectives as a result of tolerances and other quality-related design decisions.

Tolerance Specification Optimization for Economic and Ecological Sustainability

In the final stages of product development, dimensional tolerances are specified by designers to ensure high functionality at low costs. A traditional approach to this decision-making process is to minimize economic losses to the manufacturer and the consumer. This paper presents a new approach for tolerance allocation optimization that considers sustainability not only from economic costs but also ecological costs. The framework is formulated as a multi-objective optimization problem and explored with a case study on the design of an automotive body panel. Results of the case study include Pareto frontiers of non-dominated optimal solutions along with a parametric study to explore the influence of material choice on the results.

Split-­Line Design for Given Geometry and Location Systems

The spatial relations between parts in an assembly can be critical for the functional and aesthetic quality of a product. In the case of the automobile, these relations can be between doors, fenders, hood, panels, and so on. Variation in these relations, caused by part and assembly variation, influences the output variation, which is what the customer sees and judges. This paper presents a computer-aided tolerancing tool that supports and improves split-line design with respect to geometrical variation. A split-line is the relation between two mating parts over a distance. The design and placement of a split-line in an automobile body are influenced by several aspects such as design language, geometrical dimensioning, crash safety, and so on. In this paper only the geometrical dimensioning aspects have been considered. The research has been carried out using simulations and analyses in a computer-aided tolerancing software. The tool presented describes a way to calculate and visualize the geometrically most robust area and split-line between two parts. The findings from the research show that it is difficult to calculate and visualize the result in flush and gap directions in the same way. The tool gives insight into how the configuration of the locating schemes influences the geometrical robustness of the design.

Efficient design module capture and representation for product family reuse

New business models and more integrated product development processes require designers to make use of knowledge more efficiently. Capture and reuse are means of coping, but support, techniques, and mechanisms have yet to be sufficiently addressed. This paper consequently explores how computer-aided technologies (CAx) and a computer-aided design (CAD) model-oriented approach can be used to improve the efficiency of design module capture and representation for product family reuse. The first contribution of this paper is the investigation performed at a Swedish manufacturing company and a set of identified challenges related to design capture and representation for reuse in product family development. The second contribution is a demonstrated and evaluated set of systems and tools, which exemplifies how these challenges can be approached. Efficient design capture is achieved by a combination of automated and simplified design capture, derived from the design implementation (CAD model definition) to the extent possible. Different design representations can then be accessed by the designer using the CAD-internal tool interface. A web application is an example of more generalpurpose representation to tailor design content, all of which is managed by a product lifecycle management (PLM) system. Design capture is based on a modular view block definition, stored in formal information models, management by a PLM system, for consistent and reliable design content. It was, however, introduced to support the rich and expressive forms of capture and representation required to facilitate understanding, use, and reuse of varied and increasingly complex designs. A key element in being able to describe a complex design and its implementation has been capture and representation of a set of design states. The solution has been demonstrated to effectively be able to capture and represent significant portions of a step-by-step design training material and the implementation of complex design module through a set of design decisions taken. The validity and relevance of the proposed solution is strengthened by the level of acceptance and perceived value from experienced users, together with the fact that the company is implementing parts of it today.

TOWARD A METHOD FOR IMPROVING PRODUCT ARCHITECTURE SOLUTIONS BY INTEGRATING DESIGNS FOR ASSEMBLY, DISASSEMBLY AND MAINTENANCE

New customer demands and increased legislation drive business-oriented companies into new business models focusing on the entire life cycle of the product. This forces the manufacturing companies into service-oriented solutions as a compliment to the original business areas. Takata [1] postulates that “the goal is no longer to produce products in an efficient way, but rather to provide the functions needed by society while minimizing material and energy consumption”. This new situation affects the product requirements as well as product development process (PD). When focusing on the entire product life cycle, product aspects such as maintenance and repair will receive more attention since the companies will be responsible for them. In the product development process of today, especially in the automotive industry, maintenance and repair aspects (repair and maintenance methods and manuals, for example) are currently taken care of when the product is more or less fully developed. Maintenance and repair requirements are difficult to quantify in terms of core product properties (for vehicles, cost, CO2 emissions, weight, and so on). This leads to difficulties in equally considering maintenance and repair requirements while balancing vast amounts of product requirements. This paper focuses on a comparison and discussion of existing design guidelines affecting the structure and organization of parts in an assembled consumer product, such as Design for Assembly (DFA), Design for Maintenance (DFMa), Design for Service (DFS) and Design for Disassembly (DFD) methods. A tool for evaluation and analyzing product architecture as well as assemblability and maintainability is proposed.

Integrated Capture and Representation of Product Information In Computer-Aided Product Development

This paper features the implementation and evaluation of a proposed approach for information capture and representation integrated into the existing design environments at two manufacturing companies. A tool has been developed that automatically derives information from the CAD system during design and provides users with the means to capture product information that has previously been documented outside of the CAD system. Product information is managed in a PLM data model and becomes, once stored, the foundation for providing tailored views of information.Feedback from the evaluation shows that the prescribed approach was preferred to the current one and that it would likely provide value to users, both authors and consumers, of product information. This approach can reduce the time required to capture the pertinent product information. However, the primary savings are likely to be indirect as a result of increased consistency, understanding, and the potential (re)use of product information.The approach and tools presented constitute another step toward providing each stakeholder with more efficient, intuitive, contextual, and purposeful support for information capture and representation in computer-aided product development.Copyright

An Empirical Study of Information Exchange and Design Support in Product Family Development

An investigation carried out at a Swedish manufacturing company has focused specifically on information exchange and design support in and between activities in the company’s product family development process. The process allows, within a defined product family, automated generation of 3D models, product specifications, and a complete foundation for subsequent manufacture and verification.The core contributions of this paper are the investigation performed, a set of identified challenges which relate to the complexity of everyday decisions made in product family development, how these challenges can be approached and a set of tools exemplifying that approach.The study indicates that there are limitations in terms of motivation, resources and support for insight, understanding and consequent consideration to downstream implications of design decisions made. The question is whether tools and methods, which are integral aspects of the process already, might serve to further illuminate the process, maximize purposeful support and thereby minimize the efforts required to better consider downstream implications of decisions made. It is the opinion of the authors that it can, and the set of tools for information exchange and design support presented in this paper serves to exemplify how.Copyright

Current state of the art on repair, maintenance and serviceability in Swedish automotive industry – a virtual product realization approach

Sustainability with its three aspects, economy, ecology and social, is gaining more and more attention in industry as well as in academia. One way of increasing sustainability is to increase the life length of a product as well as ensuring performance by making it easy to maintain and repair. The consumer trends are moving towards a more positive attitude to buy a function rather than the product itself. By having this approach aspect such as maintenance, service and repair (MSR) is put in a different light. This paper presents a interview study with the intention to investigate the state of the art regarding maintenance and repair in four different Swedish automotive manufacturing companies with emphasis on how virtual product realization is considered and implemented. It was stated during the interviews that the use of simulation and analysis methods with emphasis on MSR differs and that it sometimes can be troublesome to make impact in project discussions etc. due to their difficulty in delivering hard figures e.g. cost, weight, CO2 emissions etc.

Sustainable Production Research - a Proposed Method to design the Sustainability Measures

This paper describes a process to develop and apply measures in Sustainable Production Research. Specifically we have: A) Conducted workshops with researchers and industry on sustainability measures and monitored sustainability awareness of the participants through concept maps. B) Developed a proposal for measures based on literature reviews, results from workshops and interviews with researchers. C) Developed a generic method for evaluating sustainability measures related to production over time. 16 sustainability measures were defined as a starting set for the continuous monitoring. Concept mapping showed that participant have an uneven view on sustainability with emphasis on technology.