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Product packaging has a huge impact on the efficiency of supply chain activities. In this research, the concept of Design for Assembly (DFA), proved in earlier studies to be effective at improving product manufacturing operations, is applied to the packaging system. We formulate the packaging system as a mathematical model for three different objectives. With respect to the continual rise in attention paid to sustainability, this research adds sustainability as one of the primary objectives. A case study demonstrates that the proposed model can achieve desired results and reveals a level of consistency among the three objectives. In addition to the application of DFA concepts to a packaging system, the contributions of this research lie in the development of a mathematical model (using integer programming and goal programming) for calculating the cost, handling time, and sustainability of the objectives in line with the design needs of the multi-level packaging size from the perspective of a supply chain to provide a range of solutions offering increased options for firms.

In automotive body assembly systems, an optimum assembly sequence planning (ASP) not only increases production efficiency and product quality, but also decreases cost and process cycle time. Typically, ASP evaluation approaches are focused on design for assembly criteria, and very few studies have considered the impact of ASP on dimensional accuracy. The major challenges involving quality-driven ASP evaluation can be enumerated into three categories: (1) batch of compliant non-ideal parts to consider real part defects; (2) variation propagation modeling in multi-station assembly (MSA) system in the presence of stochastic manufacturing errors both at product and process levels; and, (3) the development of dimensional quality criteria for quantitative ASP comparisons. This paper proposes a methodology based on the modeling of dimensional errors propagation in MSA with a batch of compliant non-ideal parts to improve product dimensional quality through optimizing ASP and assembly line configuration. It entails three main steps: (i) assembly sequence generation by k-ary assembly operation method for a predetermined assembly line configuration; (ii) variation propagation simulation taking into account a batch of non-ideal parts, station-to-station repositioning errors, and spring-back phenomenon in MSA system; and, (iii) robust optimization of ASP based on developed quality criteria which contains two quantitative indices. The potential benefits of the proposed methodology are successfully demonstrated on automotive front-rail assembly process.

Many companies have been reorganizing from a sequential to an integrated path known as simultaneous engineering, which aims to reduce development time and costs. The main problem during technology and product development is the integration of the design and manufacturing areas in the product development phase. This paper proposes a model to improve the use of simultaneous engineering by integrating project and manufacturing knowledge areas based on concepts of manufacturing readiness level, design for manufacturing and assembly and technology readiness level. Based on a bibliographic review and a preliminary study conducted over 1 year in a multinational metalworking company, a model was proposed as a method to be applied in the early stages of product development. The results show an integration of proposed engineering areas into a product development process, a cost reduction of 20% and a manufacturing investment reduction of 25%.

Tolerance allocation is a very important assignment. In fact, knowing how to allocate efficiently tolerances for assembly parts in a computer-aided design (CAD) and computer-aided manufacturing (CAM) system is a very key issue because the cost and quality depend directly on dimension tolerances. The traditional optimization approaches complain about a lack regarding the evaluation of manufacturing difficulty to solve tolerance allocation problem. In this paper, a new approach based on difficulty coefficient evaluation (DCE) and Lagrange multiplier (LM) method is presented to obtain an economical tolerance allocation. In fact, DCE technique, based on the failure mode, effects and criticality analysis (FMECA) tool, is used to quantify the manufacturing difficulty of mechanical parts, as well as the LM method is developed to optimize the proposed approach while respecting the functions and manufacturing requirements. A case study is established to verify the highlights of this work. Indeed, the computed result shows that the method can produce tolerance allocation economically and accurately according to difficulty requirements. Consequently, the proposed method is performed to exploit fully design for manufacturing and assembly (DFMA). For this, an integrated CAD/tolerancing model based on manufacturing difficulty (ICADTMD) is developed using graphical user interface (GUI) in MATLAB.

In recent years, remanufacturing has received increased attention as a sustainable and profitable product recovery strategy. To facilitate the remanufacturing of used product returns, factors which affect remanufacturability should be considered during the product design stage. The selection of fastening method during the product design stage is one of the critical decisions which affects the remanufacturability as well as the total cost of disassembly and re-assembly of used products. Hence, both product assembly and disassembly issues should be considered in the product design stage for the selection of fastening methods. Simultaneous consideration of product assembly and disassembly in the product design stage for the fastening method selection has not been properly addressed in previous studies. In this paper, a methodology for selecting appropriate fastening method from a remanufacturing perspective is proposed in which both product assembly and disassembly are addressed. In the proposed methodology, an optimization model is formulated with the objective of minimizing the total cost of product assembly and disassembly. The genetic algorithm is employed to solve the model. A case study on the selection of fastening method for a laptop computer is conducted to illustrate the proposed methodology and to evaluate its effectiveness. The effect of the degree of product disassembly and the demand size for remanufactured products on the total cost of product assembly and disassembly was also investigated. The results showed the proposed methodology provide significant cost savings in the total product assembly and disassembly cost.

Effective production in a networking environment of sheet metal products needs accurate and relevant PDM (product data management) data, appropriate modeling of components supported by local and global network solutions, and utilization of advantages of feature-based modeling. To enable these aspects of effective production in sheet metal production, it is necessary to evaluate the integration of DFMA (design for manufacturing and assembly) and PDM. This paper aims at identifying the challenges of DFMA and PDM integration through recognizing possible malfunctioning parts of their integration. The observations are based on sheet metal specimens in which the DFMA and PDM aspects are visible in punching and bending. This study will focus on five issues that are included either in DFMA or PDM, or both: the effects of different calculation methods for the flattened length, utilization viewpoints of global or local manufacturability guidelines, assembly conditions, options to tune the manufacturing process instead of changing the product geometry, and possible additional requirements given by the customers. Based on practical design and manufacturing tests, it has become evident that one option to improve the quality of analyzed sheet metal parts is to further develop the integration of DFMA features with the workshop’s cutting and punching parameters. As one possible improvement to these kinds of integration tasks of DFMA and PDM, it is suggested that the responsibilities for developing DMFA and PDM applications with proper design parameters could be analyzed more deeply between persons working with information exchange, product design, software design, or production machine design.

Remote laser welding which has benefits for both productivity and energy saving is receiving increased attention for automotive assembly lines. Introducing this innovative equipment requires a redesign process for assembly elements, for example to substitute resist spot welding with remote laser welding. The mating surfaces related to the welding need to be updated as well, but this is complicated when the shape design includes manufacturing and assembly elements based on current practice which hide the design intent. The challenge is to establish guidelines with the design parameters of automotive door frames and the process parameters of the joining process in order to maintain the design intent. In order to maintain the original design intent of the process planner, the author proposes a propagation model for the production stage which is defined as the interplay between parameters and quantitative comparison. The process parameters of remote laser welding are applied to the flange of the door frame. Also, the shape of each flange is synchronised with the changes according to the result of a quantitative comparison of the productivity and eco-efficiency. A design guideline tool to redesign the flanges was developed inside a commercial CAD system to show the proposed concept. Five flanges of a car door were subjected to redesign for introducing 4-kw remote laser welding with considerations of eco-efficiency, process time and weight change. The tools are shown to illustrate how to maintain design intent in the redesign process, and the concept was realised in a commercial CAD system.

As additive manufacturing (AM) process evolves from rapid prototyping to the end-of-use product manufacturing process, manufacturing constraints have largely been alleviated and design freedom has been significantly broadened, including shape complexity, material complexity, hierarchical complexity, and functional complexity. Inevitably, conventional Design Theory and Methodology (DTM) especially life-cycle objectives oriented ones are challenged. In this paper, firstly, the impact of AM on conventional DTM is analyzed in terms of design for manufacturing (DFM), design for assembly (DFA), and design for performance (DFP). Abundance of evidences indicate that conventional DTM is not qualified to embrace these new opportunities and consequently underline the need for a set of design principles for AM to achieve a better design. Secondly, design methods related with AM are reviewed and classified into three main groups, including design guidelines, modified DTM for AM, and design for additive manufacturing (DFAM). The principles and representative design methods in each category are studied comprehensively with respect to benefits and drawbacks. A new design method partially overcoming these drawbacks by integrating function integration and structure optimization to realize less part count and better performance is discussed. Design tools as a necessary part for supporting design are also studied. In the meantime, the review also identified the possible areas for future research.

Today the assembly sequence for the products is often carried out manually and its definition, typically, is very expensive, not guaranteeing optimal solutions. Coming up with an efficient assembly sequence is the essential step to improve process productivity and reduces the time and costs related to assembly machines and equipment. The issue related to the assembly sequence of a product depends on the total number of the its components. In particular, the number of the possible sequences can be obtained through the calculus of the factorial of the number of the product components. This work presents an automatic approach intended to define assembly sequences, based on the information regard the contacts and the interferences existing among the components, which is obtained by the assembly CAD model of the product. The level of the information required by this approach allows its implementation at early stages of design, as soon as the layout of the conceptual solution of the product is defined, independently by the method used to model the CAD assembly. The procedure proposed is focused to obtain a reduced number of assembly sequences, guaranteeing that there is at least one feasible assembly sequence among them. The procedure is oriented to iteratively identify independent and important subassemblies into the CAD assembly, then merge them to specific assembling nodes and generate sequences until the whole product is analyzed. After a brief review of current methodologies developed for assembly planning, in this paper, the automated procedure for assembly sequence generation is explained and applied on an example, obtaining feasible solutions.

Time and cost reduction during product development is important to meet the competitiveness in the market. Design for Manufacture and Assembly (DFMA) plays a key role in product development, especially in industries like aerospace, wherein variety in component geometry is more. Parts count reduction is one of the basic principles of DFMA. Design for Manufacture (DFM) considerations lead to simplification and standardization of design and manufacturing processes. It also facilitates integration of function and form and optimizes the workflow. This paper outlines the DFMA considerations to sheet metal parts considering factors such as standardization of geometric shapes and integral part design through parts count reduction. A methodology for integration of parts is presented, which is partly interactive, to evolve an integral design from a multipart sub-assembly. The method proposed is applied to a sheet metal parts sub-assembly, and it also compares the time and cost of manufacture and assembly.

A good assembly process plan can increase the efficiency and quality, and decrease the cost and time of the whole product manufacturing process, which is important as product and production demand changes rapidly in today’s market. Several approaches using different techniques and methodologies have been developed and reported in the literature for assembly process planning. Automated assembly process planning (AAPP) has been the main focus of the research efforts over the years, with most work concentrated on attempting to automate or to semi-automate the key sequencing process. However, some of these efforts have not been successful in general, and many assembly process plans are still based on traditional methods. The purpose of this paper is to review and outline the methodologies and tools in assembly process planning developed during the past ten years, such as the application of meta-heuristics methods to find the optimal/near optimal assembly plans and assembly line balancing, the evaluation methods for design for assembly (DFA), and collaborative assembly process planning systems. Based on this review the future trends in this area are also identified and discussed.

In previous work, researchers have expanded the definition of product modularity from function-based modularity to life-cycle process-based modularity. Our previous work in this area also developed and validated a modularity measure and modular product design method to improve life-cycle product modularity. However, we found that a correct modularity measure and modular design method are not enough to realize modular product design. How the measure and design method are used, especially the role of modular product representation, is an important aspect of modular design and imperative for realizing cost savings. In this paper, we develop a representation for component-component similarity and dependency that is based upon the most significant elements of product modularity. The life-cycle application we have chosen is the assembly process due to the audience’s familiarity with design for assembly methodology. The process similarity representation is based on assembly cost factors including tool changes and fixture changes. There is a clear reduction in non-value added time in the assembly process if these elements are the same for all components in one module. The process-based design dependency representation is based on design features that impact the assembly process (faces, fasteners, assembly interference, etc.). If components are independent of other components not in the same module with respect to these elements, the redesign of components in one module will not affect the assembly process of other modules. An example is used to show the application of these representations. The work in this paper establishes how to represent similarity and dependency for the assembly process. We plan to expand the representation to other life-cycle processes in the future.Copyright © 2006 by ASME

Current computer-aided assembly systems provide engineers with a variety of spatial snapping and alignment techniques for interactively defining the positions and attachments of components. With the advent of haptics and its integration into virtual assembly systems, users now have the potential advantage of tactile information. This paper reports research that aims to quantify how the provision of haptic feedback in an assembly system can affect user performance. To investigate human–computer interaction processes in assembly modeling, performance of a peg-in-hole manipulation was studied to determine the extent to which haptics and stereovision may impact on task completion time. The results support two important conclusions: first, it is apparent that small (i.e. visually insignificant) assembly features (e.g. chamfers) affect the overall task completion at times only when haptic feedback is provided; and second, that the difference is approximately similar to the values reported for equivalent real world peg-in-hole assembly tasks.

VA (virtual assembly) provides a more efficient, intuitive and convenient method for assembly process modeling, simulation and analysis. Previous researches about VA are almost isolated and dispersive, and have not established the understanding and definition of VA from a macroscopical and integrated view. Based on the analysis of the connotations of VA, a PLO-VATA (product lifecycle-oriented virtual assembly technology architecture) is proposed, in this architecture, VA is decomposed into four basic elements: principles and methodology of DFA (design for assembly), assembly analysis and evaluation, virtual assembly model and virtual assembly toolkits. Immersion, concurrence, integration and collaboration are the four main characteristics of VA being put forward. The key techniques of VA including virtual assembly model, virtual assembly analysis and evaluation, and virtual assembly process planning are discussed. Finally, a prototype system is built to validate the feasibility of the proposed method.

Assemblability analysis and evaluation plays a key role in assembly design, operation analysis and planning. In this paper, we propose an integrated intelligent approach and framework for evaluation of assemblability and assembly sequence for electro-mechanical assemblies (EMAs). The approach integrates the STEP (STandard for the Exchange of Product model data, officially ISO 10303)-based assembly model and XML schema with the fuzzy analytic hierarchy process for assembly evaluation. The evaluation structure covers not only the geometric and physical characteristics of the assembly parts but also the assembly operation data necessary to assemble the parts. The realization of the integration system is implemented through a multi-agent framework. Through integration with the STEP-based product modeling agent system, CAD agent system and assembly planning agent system, the developed assembly evaluation agent system can effectively incorporate, exchange, and share concurrent engineering knowledge into the preliminary design process so as to provide users with suggestions for improving a design and also helping obtain better design ideas. The applications show that the proposed approach and system are feasible.

A product assembly or disassembly is completed by means of proper tools. The selection of feasible tools is an important process in planning a complete assembly or disassembly sequence. A key tooling consideration in assembly or disassembly planning is to reason the available space for a tool application during the assembly or disassembly of a product. Currently, assembly tool reasoning about space mainly depends on simulation-based or user-interactive approaches because of its computational complexity. These approaches are inappropriate in dealing with various what-if scenarios regarding assembly or disassembly planning in a rapid product development. They also depend on users’ expertise or experience in assembly or disassembly. This paper presents a novel approach to the geometric feasibility analysis for fast assembly tool reasoning. Techniques described in this paper are advantageous not only in the aid of generating a complete assembly or disassembly plan but also in the efficient support of such systems as computer-aided assembly planning (CAAP), design for manufacturing (DFM), design for assembly (DFA), design for disassembly (DFD), and computer-aided tool selection (CATS).

This paper presents the results of a research investigation undertaken to develop methodologies and techniques that will reduce the cost and time of the design, manufacturing and assembly of mechanical conveyor systems used in the food and beverage industry. The improved methodology for design and production of conveyor components is based on the minimisation of materials, parts and costs, using the rules of design for manufacture and design for assembly. Results obtained on a test conveyor system verify the benefits of using the improved techniques. The overall material cost was reduced by 19% and the overall assembly cost was reduced by 20% compared to conventional methods.

Assembly, one of the oldest forms of industrial production, and its twin area, disassembly, have enjoyed tremendous modernization in the era of the information revolution. New enabling technologies, including prominent examples such as virtual CAD, Design for Assembly and Disassembly (DFAD), robotic and intelligent assembly, and Flexible Assembly (FA), are now becoming commonplace. This article reviews some of the newer solutions, and an extended framework for Cooperation Requirement Planning (ECRP) in robotic assembly/disassembly is developed. Recent research under the PRISM program at Purdue University to enable ECRP and other relevant projects is presented. The challenges to researchers in this field, in adapting these solutions to the emerging environment of global and local supply networks are also discussed.

Virtual product creation and product design analysis are essential for studies in the investigation into assembly feasibility and help reveal practical manufacturing constraints. This paper demonstrates an application of a virtual assembly tool DYNAMO for a grill plate assembly. Virtual simulation and assembly verification is illustrated. Both virtual simulation and assembly verification enable designers to identify potential assembly difficulties encountered in manufacturing and thus save time and cost in real production. The paper also examines factors that influence the efficiency of assembly, namely, assembly method, assembly sequence, and assembly time. Suggestions for redesign for assembly improvement provided by some design for assembly methods are also discussed.

An injection mould is a mechanical assembly that consists of product-dependent parts and product-independent parts. This paper addresses the two key issues of assembly modelling for injection moulds, namely, representing an injection mould assembly in a computer and determining the position and orientation of a product-independent part in an assembly. A feature-based and object-oriented representation is proposed to represent the hierarchical assembly of injection moulds. This representation requires and permits a designer to think beyond the mere shape of a part and state explicitly what portions of a part are important and why. Thus, it provides an opportunity for designers to design for assembly (DFA). A simplified symbolic geometric approach is also presented to infer the configurations of assembly objects in an assembly according to the mating conditions. Based on the proposed representation and the simplified symbolic geometric approach, automatic assembly modelling is further discussed.

It is very important to know how to allocate tolerances economically for parts in a CAD/CAM system because this directly affects the machining costs.of the parts, A new approach based on fuzzy comprehensive evaluation (FCE) and a genetic algorithm (GA) is presented to obtain a rational tolerance allocation for the parts. First, the current methods for tolerance allocation are reviewed in detail. Then, FCE is used to evaluate the machinability of a part; a new optimal model, which can fully exploit DFA (design for assembly) and DFM (design for manufacturing), is established by combining the functional sensitivity factors and machinability factors of parts. A genetic algorithm (GA) is developed and used to optimise the above model. Finally, an actual example is used to verify the feasibility of the above method; the computed result shows that the method can produce tolerance allocations economically and accurately.

This paper addresses the development of an expert system for concurrent product design and assembly planning (CDAPFAES) including conceptual design, detailed design, assemblability analysis and design for assembly, assembly system design, assembly process planning and stimulation, and technical-economics justification. This approach is implemented through an agent-based framework with concurrent integration of multiple cooperative knowledge sources and software. This intelligent system can offer systematic assistance for assembly design and planning in the early stage of product development and facilitate, as far as possible, the use of flexible assembly equipment, including robots. Finally, this new design methodology is illustrated with a successful implementation of switch product design.

This paper reviews the relevant literature of the development of methodologies and systems for integrated intelligent design of assembled products and processes. Based on a combination of the concurrent engineering approach and artificial intelligence techniques, an assembly oriented intelligent scheme for the integration of design and planning is proposed, in which the following components or activities are considered and carried out concurrently and intelligently: assembly modelling and design (conceptual design; preliminary design; detailed design), assembly process planning, assembly system layout and design, assembly simulation, econo-technical (e.g. assembl-ability, assembly time and cost) and ergonomic analysis and evaluation. The literature is reviewed and discussed in relation to the methodologies and systems of implementing the above components or activities and an integrated environment to support them. In addition, some research of our group on this topic is introduced.

An integrated concurrent engineering methodology for developing a baby carriage is proposed. The development process is divided into three stages for considering the design, manufacture, and assembly problems. The product is first designed based on design criteria to ensure the best matching of needs and requirements. Then the parts and machine tools are coded using group technology (GT). The machine groups and the parts to be processed are given in matrix form using the production flow analysis (PFA) method. The machine cells are arranged based on the balance analysis of process time, and a flexible manufacturing system (FMS) is planned. Finally, the assembly line is planned based on the relationship of the parts. Some related parts are collected as a subassembly system. After the subassembly is decided, the work stations are arranged based on the required assembly time to obtain a high-performance assembly line. The results show that not only is the production cost of the product reduced, but also that the competitive properties are improved. This model can also be applied to develop other products.

Companies are increasingly being put under pressure from the market to design product and production better, faster, cheaper and more market-oriented. Insufficient coherence and synchronization between product, process and system design often lie at the basis of great design efforts and high design costs. This paper focuses on this subject, by introducing an integral assembly model to improve the insight into the interaction between product, process and system design. The objective of this model is to realize a controllable design process.

Typical mechanical products can be assembled in various sequences of assembly operations. These sequences have high impact on the assembly time, machine utilization and even on the product quality. In order to select the best sequence of assembly operations, proper evaluation of the various sequences of assembly operations is required. This, in turn, requires the consistent evaluation of each assembly operation in the sequence. The assembly operations can be evaluated for various criteria, of which the operation difficulty is the most meaningful. This paper describes a methodology to analyse the assembly operations and calculates an operation’s degree of difficulty using an expert system. This analysis consists of two steps: the first one identifies the main parameters that affect the assembly difficulty and assigns fuzzy triangular values to these parameters. The second step assigns weights to the parameters in order to maximize the agreement with a domain expert. The expert system analyses the difficulty of the assembly operation performed in two orientations: horizontal and vertica1. The expert system then assigns a triangular fuzzy number as the aggregate measure of the operation’s difficulty.

Increasing demands for lower cost of goods, due to international competition, has developed a new area of rationalization for increased productivity which can be achieved by applying new radical methods of production principles. Design for Assembly (DFA) is one of such methods that should be considered in the early design stage in order to cope with the increasing demands of lower cost, improved working environment, and higher wages. When Axiomatic Design (AD) is implemented with DFA in an intelligent way, a new area of design concepts would be realized. This study examines some elements of intelligent design systems to assess manufacturability of a product through the development of a knowledge based expert system for assembly (KBESA). The knowledge base has been acquired from DFA along with AD concepts with emphasis on the conceptual design stage where the structure of the product as a whole is considered. These concepts have been implemented in a case study illustrating its applicability.

Automated assembly in the electronics industry offers many advantages over traditional assembly methods. As product lives become shorter and batch numbers become smaller, new programming methods will be needed to shorten the lead time for these automated lines. Providing a method for humans to interact with the robot in a natural language mode will lead to some of these advantages. Task-level programming deals with the interactions of objects rather than robot motions and therefore requires little robotic expertise but allows for easy and fast programming. One of the long-term projects aimed at alleviating the above problem is the development of a Robotic Assembly Language Planning Hierarchy (RALPH), a task-level automatic robot programming language with natural language commands. In surface mount assembly, the PC board must be populated with chips with high tolerances—a few thousandths of an inch. The part features are so small that human assemblers constantly make mistakes. The redeeming aspect of the components with regard to assembly lies in the geometry of the features. In this article we capitalize on the above geometric attributes of chips and chip pads on PCBs in order to apply the principles of RALPH in the development of a system for automatic assembly.

This paper presents the results of a study of assembly times for electrical connections and wire harnesses. The various types of electrical connection are described, together with the assembly of wires and wire harnesses. Comparisons are made of the times for the assembly operations associated with each type of connection, obtained from a variety of sources. From these comparisons, estimates are made of average or recommended assembly times. Finally, the recommended times are presented in the form of classification schemes for use by designers during the early stages of design.

A scheme of representing assemblies and an algorithm for the tolerance chain generation are developed so that tolerance chains of assemblies can be generated automatically to accommodate tolerance analysis at the assembly level. In the hierarchical data structure representing an assembly the connectivity information is carried by the instances of components and subassemblies, and the mating relations between each pair of mating entities are described by mating links, mating paths, mating conditions, and mating features. Mating graphs are derived from the mating links before they are searched for the generation of tolerance chains. The scheme has been implemented in a prototype interactive package that allows the user to model assemblies directly without detailed object modeling. Several examples of various complexity have been tested with success.

The results of the applications of design for assembly techniques to two typical designs are presented. Consideration is given to the total product cost and it is found that major cost reductions can be achieved even when assembly costs are relatively small. It is also found that assembly automation becomes more difficult to justify as a product design is gradually improved.