Search

This paper presents a new methodology for designing modular products taking into account assembly complexity and Design for Assembly. DFA encourages components integration to reduce assembly time, while modularity promotes partitioning and decomposition of product architectures into components and modules to facilitate interchangeability. A product granularity level determines the details of its architecture. The best product architecture granularity level, and size and number of product modules are determined using Cladistics – a hierarchical classification tool – along with the Design Structure Matrix (DSM) and assembly insertion and handling complexity indices. A case study using a DC vibration motor is used to demonstrate the application of the presented methodology. It is observed that increasing assembly complexity promotes coarser product architecture granularity and more modularity results in finer product granularity. Use of the presented design methodology achieves the best trade-off bet...

There is extensive evidence to suggest that industrial products are being designed with an excessive number of parts and, invariably, many more costly and complex assembly operations than should be the case. A feed forward or proactive approach to the application of Design for Assembly, aimed at influencing the design process to overcome these problems, is presented. This paper reports on progress towards the development of the Design for Assembly ‘Sandpit’, where Design for Assembly procedures are integrated with advanced computer-aided design concepts to realize an assembly-oriented design environment. A case study is included to help illustrate the ways in which the approach can be used in industry.

This paper presents a procedure for decomposing design for X (DFX) analysis techniques into individual sources of information. These sources of information are then evaluated for quality and utility. This process ensures that only those analysis tools of benefit to the designer are being employed. By determining an overall analysis structure for the DFX technique, it is possible to determine whether the overall procedure is in fact feasible or necessary. This is achieved through identifying the focus of the analysis tool and mapping this focus on to the product development process. The overall procedure is clarified through an evaluation of the Boothroyd and Dewhurst design for assembly technique.

Summary A product redesign approach that is based on design-for-assembly (DFA) evaluation results has been developed to facilitate the product modification process. This DFA-based product redesign approach (DBPRA) combines assembly functional presentation (AFP) and a problem recommendation driven mechanism (PRDM) with DFA. DFA is used to evaluate a product from the viewpoint of assembly and product design. AFP is used to identify the essential functional hierarchy of a product and to assign to it problems found as a result of DFA evaluation, and the contact information between any two mating parts. The PRDM provides a guide for design modification at the appropriate level of the product structure. The combination of AFP, PRDM and DFA is an effective redesign approach since, in addition to traditional part or component design modifications (local design changes), it results in functional area modifications (global design changes) that dramatically improve the existing design without sacrificing essential f...

SUMMARY SUMMARY Rearranging component positions and orientations inside products can reduce the acquisition times associated with handling distance and component orientation. Modeling the acquisition process with an information-based design for assembly methodology identifies and quantifies acquisition difficulty for manual and automatic processes. Heuristics based on evaluations of acquisition difficulty guide the relocation and reorientation of components inside the product to reduce assembly time. Since acquisition time averages one third of the total assembly time, significant improvements are shown to be feasible. A new information flow from downstream assembly issues to product design is demonstrated

SUMMARY The GAPT model describes the application of design tools such as design for assembly (DFA), failure mode and effect analysis (FMEA) and quality function deployment (QFD). According to the GAPT model, design tools can be used on four different levels: guidelines; analysis of product features; product reviewing; and team-building. These four levels result—in the order given—in increasingly extensive consequences for the product development work. The implementation of the DFA method has been followed in three product development projects for two years. Designers, production engineers and project leaders were interviewed before, during and after the implementation. The findings demonstrate that the DFA method can be used for four different purposes, corresponding to the levels of the GAPT model. On the team-building level, the application of the method contributed to more cooperation between designers and production engineers, and better communication. Conditions and outcomes when using the DFA method...

SUMMARY Current design for assembly methodologies stresses the importance of part features related to acquisition and orientation in determining time values and error rates. This paper discusses an approach to detecting and evaluating features of CAD modeled parts which contribute to assembly difficulty. An evaluation basis is described and algorithms are developed which give an index of difficulty with respect to orientation features and degree of symmetry for two- and three-dimensional parts. Limitations of the method are discussed with examples.

SUMMARY This paper introduces the role and value of design for manufacture tools and techniques in a team-based simultaneous engineering design process. The Lucas design for assembly techniques is described and the benefits of its use in terms of parts count reduction, assembly cost reduction and product cost reduction are given. A second technique, quality function deployment, is outlined and its advantages listed. Finally, an implementation strategy for design for manufacture is recommended.

SUMMARY Dispositional mechanisms are chains of relationships in the course of a production sequence. Improper dispositions can lead to degraded or excessively expensive products, while good dispositions can lead to ideal conditions in other areas of the company, and to optimal products. There is a need to isolate dispositional relationship in order to be able to use this very powerful rationalization tool in industry. A number of examples from industrial practice, together with experience from the areas of Design for Assembly, Design for Manufacture and Design for Cost, show that there exist certain important rules for making decisions. These disposition rules knit together different areas of the company, and have great influence on the results of R&D and on the costs which arise in the individual departments. Because of the advantageous effects associated with these factors, there is a need to investigate and isolate dispositional mechanisms, and to show how to handle them in industrial circumstances. Th...