Design-for-Assembly (DfA) and Conceptual DfA criteria are used in the generation of cost-effective assembly sequences for complex products. The design freedom suggests optimal solutions in the assembly time minimization problem regardless of costs and issues about materials and manufacturing processes selection. The goal of this approach is to investigate how the application of the conceptual DfA affects material and manufacturing costs (Design-to-Cost). The outcome is an approach to support designers and engineers in the re-design process for the product development and cost reduction.
Different Design-for-X (DfX) methods have been developed in recent years to aid designers during the design process and in the product engineering stage. Methods for efficient Design for-Assembly (DfA) are wellknown techniques and widely used throughout many large industries. DfA can support the reduction of product manufacturing costs and it provides much greater benefits than a simply reduction in assembly time.
The DfA technique can be applied during the conceptual design phase when decisions greatly affect production costs. Its main scope is to minimize the assembly time and costs by reducing components without using detailed product models. Even so, the conceptual DfA, as the authors call their method, do not consider manufacturability aspects such as the material selection or the most appropriate process to build up components and parts. Furthermore, product design and optimization is a multi-objective activity and not only limited to the assembly aspects.
The idea is to optimize assembly and manufacturing within a cost-driven approach able to evaluate the cost of manufacturing process in the early design stage when the product model is not yet available and defined. The main goal is to define a multi-objective design approach which aims to have a comprehensive analysis of the manufacturing aspects (including assembly, materials, processes, costs and times). This is particularly important to avoid design solutions which can be excellent from the assembly point of view but not costefficient in terms of manufacturing costs and investments.
Preliminary data are necessary for the multi-objective assessment. In particular, the alternative design solutions retrieved in previous steps are analyzed based on cost estimation based on designers/engineers knowledge. The concepts of DfA, DfM and DtC are applied at conceptual level to choose the best assembly configuration (best design concept) in terms of costs and productivity. This is an iterative process in which all design solutions are evaluated to retrieve useful suggestions for the development of a product and its constituent components.
The best design concept is not the best assembly concept optimized considering the minimum cost for the parts manufacturing, but the optimal solution in terms of costs, assembly, material and manufacturing process considering the production rate (batch) and other product features.
In the embodiment design phase, based on the conceptual design solution selected, different properties and parameters are defined such as the specific material or the specific manufacturing process. Furthermore, process parameter optimization (virtual model definition, manufacturing process parameters tuning, assembly lines arrangement, etc.) derives in this step by the traditional design tools (CAD, FEM, etc.). Afterwards, the detailed design is defined and physical prototypes are realized before to start the production phase.
Dr. Ben Chouchaoui
Operations Manager
WIDL Inc.
January 1, 2024
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