Applying Successive Wave Iterations to Evaluate Functions and Define Industrial Design Solutions

Abstract

The search for competitive edges in the current industry has required conceptual changes in the policy for the development of new economically, environmentally and socially sustainable products. In this direction, assessing the functions of a product and associating them with its manufacturability aspects has been crucial for the cost reduction and for obtaining a more balanced design regarding the value that the customer perceives and the real cost of manufacturing each one of its functions. However, there are still no relevant studies that present the current state of the art regards methods that iteratively interrelate the integrated product development process phases. Firstly, this paper presents a systematic review and content analysis of recent research to define the current frontiers of study. As a second step, it is proposed a model oriented to balance between function value and solutions cost throughout the new products development. Then, to validate, the proposed model was applied to a real case of the consumer goods industry. Among the results, this chapter presents a report showing the relevance of the information collected, the feasibility of the method, its particularities, impacts and limitations.

1. Introduction

In a highly competitive scenario where technology companies need to launch new products more and more quickly, with more quality and with a lower transformation cost, systematic adjustments in the traditional processes of product development (PD) are necessary. Thus, for this search for the continuous evolution of the development process to occur, the scientific world has been working with new proposals and analyzing their effects. This joint effort between academia and the industrial world seeks to develop proposals to complete the formal activities of developing new products within budgetary limits and, above all, generating the possibility of high profitability with the lowest possible risk. For this, each company follows a product development process (PDP) that is more suitable for its business, but which aims to divide the activities of this PDP into phases and stages, in order to systematize the creative process and assist in decision-making. However, whatever the industrial scenario, the definition of phases and stages starts from the project requirements defined by the governing body of organizations based on the voice of the customer and marketing strategies, in order to accommodate the diversity of consumer preferences [1]. These requirements define the restrictions and characteristics of a product and its information must be effectively shared in different phases of the PDP without any loss of meaning [2]. As the requirements are the guiding thread of a product project, all the activities defined throughout this stage of the life cycle keep their eyes pointed at them, but taking into account the needs of all the characters involved in the other stages of life of this new consumer good. Therefore, the interests of the most diverse areas, such as marketing, industrial design, product engineering, manufacturing, quality, logistics, purchasing, technical assistance and the environment, must be discussed at all stages and stages of development. This multidisciplinary work in a concurrent engineering (CE) environment generates collegiate decisions that, at first, reduce the project time by working each step no longer serially, but in parallel, but mainly, reduce future rework.

The need to work in this environment of simultaneous engineering (CE) caused the boundaries between the various departments that existed in technology companies to fall, transforming the product development process into an integrated activity (IPDP). However, even in a simultaneous engineering environment where the various actors involved in the product’s life cycle work together at each development stage, it is noticed that some stages are treated very isolated. That is, the walls between the areas of the companies were torn down, but the walls between the phases and stages of the IPDP are still up. As a result, fundamental discussions to define a product, carried out in previous stages, are avoided from returning to the debate and great opportunities can be lost, such as the balance between value and cost [3].

When developing new products, it is important for project teams to understand consumers’ perceptions of products, as the success of these products largely depends on the level of customer satisfaction [4]. The search for a balance between value and cost coincides with the search for a project’s success, as it has already been confirmed that the better this balance, the greater the probability of commercial success of a new development in the market. As discussed by [5], customer satisfaction is essential for business survival. And this satisfaction is only achieved with the perception of value associated with cost realization. On the other hand, the approaches still treat these two quantities separately, which suggests that the boxes of activities and steps of an IPDP should be open and the discussions no longer take place inside each box, but around them.

Based on this, the objective of this chapter is, firstly, to identify the state of the art regarding the interrelationship and cycles between project phases that discuss value and cost. As well as the frontier of knowledge between the conceptual and preliminary design phases, within which, in a classic way, the perceived values of each function and their associations with the manufacturability aspects generated by the selected solutions are discussed and pondered. From this point, a method is proposed and tested that seeks the balance between these quantities - value and cost - of each function.

For this, this research searched the existing literature for scientific methods or models related to this universe of study. Weighing the relevance, scope and practical applications of the studies and the impact of the respective journals and authors in the area of development of innovative products oriented to technology industries. Thus, this study is initially composed of a systematic literature review, followed by content analysis, with the objective of generating reflections on the interactions between the phases and stages of defining the functions and solutions in the IPDP, culminating in the application of a method in a real industrial design case of the consumer goods industry.

2. Integrated product development process (IPDP)

Integrated product development (IPD) should be understood as a managerial approach to improving product development performance by managing overlap, parallel execution, and concurrent workflow of activities [6]. The study of the steps that make up the integrated product development process (IPDP) in a simultaneous engineering environment shows the importance of using tools to aid in planning and decision-making. As argued by [7], a transfer in the flow of information occurs naturally throughout the life cycle of products and this flow must be systematized. As cost minimization is always one of the goals that a company seeks, the in-depth evaluation of alternatives in a systemic way becomes fundamental to help engineers and other members of a project team to make the decision on the best configuration.

To start an IPDP it is necessary to clearly define which product family will be worked on, which target consumer share and which potential functions can be added. To try help the project team in these issues, there are good methods and development models that use the concurrent engineering premises as a basis and encourage integration between all stakeholders and departments of an organization. Design tools that include value engineering (VE) and design-for-assembly (DFA) techniques are recurrent resources in some of these models, as we will see throughout this chapter. However, the ideal time for application of VE and DFA has not been discussed in depth in the research published so far. Thus, such definitions will be proposed throughout the presentation of this model.

Systematic design methodologies prescribe step-by-step procedures, from functional representation, decomposition and solution search to conceptual, preliminary and detailed design [8]. As argued by [9], due to the increasing number of requirements and the introduction of new technologies, current trends indicate that more disciplines were involved in the design of a product. More and more projects are developed with the participation of actors from the most varied areas, especially in the conceptual and preliminary phases. In order to achieve integration between these multidisciplinary characters, more and more researchers focus on the interface between them, as the information interface plays a very significant role in ensuring that the components defined by designers from different disciplines integrate correctly and eventually help them achieve integrated design.

Always with an eye on performance requirements, which are the constant reverberations that the voice of the customer generates in each decision-making meeting, most authors divide knowledge into two types: explicit knowledge and tacit knowledge – know-how – and the integration of this knowledge of actors from various backgrounds, personal experiences and actions in different departments of a company defines the process of integrated product development [10].

The modern integrated product development process (IPDP) has required simultaneous collaborations of multiple groups, producing and exchanging knowledge and information from multiple perspectives, such as design, manufacturing (including molding, machining, assembly, inspection, etc.), in addition to the disposal, remanufacturing, marketing and other perspectives, within and beyond institutional boundaries [11].

In the same sense, IPDP can be defined as the traditional way of organizing information and defining the steps for creating a new product. Setti et al. [12] show that developing a new project is a complex task that involves all the functional areas of a company and requires the simultaneous work of a multidisciplinary team. This applies both to an isolated product and to a family of products, where one of the important tasks in this complex problem is the determination of optimized architectures of product families, with the product architecture being the arrangement of functional elements that must be foreseen in each one of the formal steps of the IPDP [13].

The steps of an IPDP may vary from company to company, but invariably they are divided into three very well characterized phases, with their own nomenclature. Within each of these phases, design tools are used to assist in decision-making. The project is only “promoted” to the next phase if, in a collegiate manner, each of the intermediate stages is fulfilled. However, what are these phases? As mentioned, the names may vary, but, a priori, they always deal with specific subjects. The first phase addresses issues related to the definition and analysis of the “functions” of the new product. The second deals with issues and decision-making tools regarding the solutions that will be adopted. The third discusses and defines the technical specifications, prototypes and tests.

For some time, as described by [14], it is emphasized that for real integration, the cooperation of teams from various areas of training and interest within a company such as Marketing, Design, Research, Product Engineering, Industrial Engineering, Quality, Logistics, Manufacturing, Sales and After-Sales, for example, that working together and looking towards the end customer throughout all the intermediate activities of the project, define the success or failure of a product. Each design method used in each stage of the IPDP phases must be structured through discussions between the representatives of the areas, forming a simultaneous engineering environment, as illustrated in Figure 1.

Figure 1.

Three phases of product development immersed in a concurrent engineering environment.

Approaching the development of a new product in this systematic way, the work team naturally ends up considering all aspects related to innovation, production, marketing and after sales. As well as, all the “actors” impacted throughout the life cycle can be listened when was defined the functions and their values, the possible solutions and their costs, and other issues like investment demands and deadlines.

3. Concurrent engineering in the IPDP context

As previously described, a product development (DP) to be considered an integrated development process (IPDP) must structure its activities in a concurrent engineering (CE) environment, where the parallel work of the various members of a multidisciplinary team makes if indispensable. Therefore, the definition of this work philosophy becomes highly relevant.

This concept was first introduced in a report presented by the US Department of Defense (IDA) in 1988 [15, 16]. Since then, this standard of work based on CE has become the main choice for many companies to restructure their processes and carry out an integrated management system, due to significant savings in time and development costs, in addition to improving the quality and quantity of innovations. For the participation of representatives from all sectors of the company in all phases and stages of the IPDP.

In this way, projects, in general, should be understood as a momentary task force. That is, each new product to be developed must be worked on a systemic way with the representatives of the departments that will suffer the direct or indirect effect of it. This development team will be meeting for a predefined time and using all of its technology inventory to include their demands as soon as possible. For this, a matrix management and an integrated work in a concurrent engineering environment becomes essential for any organization to remain competitive and in a constant process of innovation. Therefore, it becomes essential that all levels of an organization understand the philosophy of simultaneous engineering and know how to work in this environment. Each design tool used in each stage of the IPDP phases must be structured through discussions between representatives of the various departments that will be involved throughout the life cycle of that future product, forming an environment of simultaneous engineering, as illustrated in Figure 1. With the development of engineering systems, concurrent engineering has received more and more attention.

Recently, many CE technologies have been developed to solve integrated and simultaneous design problems of engineering systems [17]. However, CE can be understood as both a philosophy and the creation of an environment. In the field of philosophy, it is the foundation for meeting stakeholder requirements at the time of conception. Thus, avoiding reworks that generate cost increases and development time. Thinking of the CE as creating an environment, it encourages the project team to work together, with activities in parallel and with the participation of everyone in the decision-making process. This generates gain in opportunities, deadlines and, above all, guarantees the commitment of the agents impacted by the new project.

As described by [18], the process of integrated development of new products is complex, in part due to the broad areas of expertise that need to work together to achieve the best results and from the most varied points of view of representatives from all over the world. The areas involved in the life cycle of a new product that are fundamental to compose the definitive configuration of the functions and solutions of this development and that need to be analyzed. Therefore, each decision must be taken in a collegiate way, that is, with the discussion and active participation of all interested parties, that is, representatives of all key areas of the company that will be part of or will be impacted throughout the entire life cycle of this new product. A well-structured development process can increase the likelihood of success for a new product that would need years of experience from the team members or eventual inspirational insights from an industrial designer, a product engineer or marketer. The systematization of the creative process added to the years of experience and knowledge of IPDP philosophies can be a differential to reduce the probability of failure of a new product in the market [19].

Some researchers argue that this mode of simultaneous work effectively improves the stability of the design process [20]. Collegiate decisions between members from all areas of the company must occur throughout the development process. In this sense, [21] argues that every day, more companies are discovering that the real increase in productivity starts with factors such as clean and efficient processes, good communication infrastructure, simultaneous engineering, collaboration and teamwork. The CE methodology is applied in the early stages of new product development in various sectors of modern industry and is combined with multidisciplinary design optimization. The formalization of the activities of each phase and stage of the IPDP makes the development process faster and the results obtained safer in terms of investment protection, as it seeks to minimize errors and lost opportunities. In addition, it commits all areas of the company in every decision to be made.

The way in which the execution of each activity is defined, according to [22, 23], it should involve each member of this development team to define each aggregate function and each solution defined for the new product. Thus, project development methodologies based on simultaneous engineering tend to have a fundamentally multidisciplinary character conception.

This cycle of product development, which follows the system of first dealing with functions, then discussing solutions and then defining the specifications, in an CE environment, has been treated in the literature as IPDP, where its three formal phases can be described as: conceptual design, preliminary design and detailed design [24, 25]. In this sequence and through its processes, the company is able to create products in a CE environment, more competitive, in less time, being able to meet the constant evolution and demand of the market.

The ultimate target of concurrent engineering is to encourage research and development (R&D), product, manufacturing, PCP, sales and marketing teams to work together in a series of common, pre-established activities. However, people are the ones who make innovation happen, so only with a team trained in the IPDP concepts will the gains be realized. This team must work together from conception. As well as, it must be good communication of decisions made by specialists and by dedicated teams. These stimulator and communicator roles are one of the many activities expected of a good project manager.

The flow of communication and information between specialists is crucial for the success of higher education. In this approach, the conceptual is distributed to all specialists, at which point each one can comment on the project in relation to their own area of expertise [26]. These people who have this expertise must come to a consensus on each decision when conceptualizing the new consumer good. They together, can achieve an optimized product in order to meet the project requirements, add functionality, improve productivity, reduce cost in a shortest possible time. Therefore, design tools to systematize these discussions must be designed and used to organize the decision-making process. At each stage of the IPDP, decision-making must be collegiate, creating an environment of simultaneous engineering between the areas and between the phases of development. With this, the opportunity for innovations and technological synergy is greatly increased through the exchange of information on the heterogeneous competences of the different characters.

4. IPDP phases and steps

Traditional product development (PD) projects are implemented within strict time and resource limits. Technological changes accelerate with intensified global competition, which rapidly changes customer preferences and shortens the life cycles of new products [27]. So, since PD is just one of the inherent activities of the entire lifecycle, it is important to view it within this context. For this, [28] propose that this cycle be divided into seven generic phases that can be adapted to meet the needs of individual projects. They are: Idea generation, Pre-development, feasibility, product development (PD), commissioning, launch and post-implementation review. But they may have alternative names according to the characteristics of the company, as shown in Table 1.

	Product life cycle phases	Alternative names
Pre- Development	Idea generation	Proposal	Concept	Ideation
	Pre-feasibility	Initial investigation	Initial assessment	Research
	Feasibility	Definition	Business case	Authorization
Development	Development and execution (PD)	Implementation	Construction / Build	Develop and test
	Commissioning	Trial	Beta test	Validation
Pos-Development	Launch	Release	Implementation	Acceptance
	Post Implementation Review	Business review	Project audit	Post project review

Table 1.

The seven stages of the product lifecycle. Adapted from [28].

Other approaches, such as the one advocated by [29], divide the cycle of a product into just two phases, planning and execution. However, the fine activities are the same and occur in the same sequence listed in the previous discussion and in a continuous cycle between projects. Thus showing that, more important than the name of a given phase, the activities and skills worked on in them are what matters most.

What can be seen is that the most recent studies avoid closing the “boxes”, both of the stages of the product life cycle and of the phases and stages of each of these stages, such as the one covered in this chapter, which focuses on the design and development (PD) stage. These same current studies, such as the one presented by [30], in addition to opening these “boxes”, propose cyclical evaluations between them, as seen in Figure 2. This spiral PDP proposal repeats regular steps, including concept development, system-level design, detailed design, and integration and testing. The process is flexible; the actual number and range of loops may vary.

Figure 2.

Spiral between the phases of a product’s life cycle. Adapted from [30].

The PMBOK® guide [31] defines a product design as “a temporary effort undertaken to create a unique product or service”. For this, this process must be systematized and organized so that all relevant issues, which will have impacts throughout its life cycle, are discussed and worked on. The approach of these activities simultaneously between the areas guarantees the improvement of the flow of information and the fulfillment of the project requirements. Thus, the integration of the characters involved throughout the entire life cycle during the development phase generates the concept of integrated product development (IPD).

This chapter argues that there is a strong competitive advantage in the integration of design and development activities, not only among the multidisciplinary agents working together throughout the phases and stages, but also in the integration between the phases themselves. This systematization transforms the DIP into a logical process, where the continuous flow of information would guide the management of activities and facilitate decision-making. We call this, then, the integrated product development process (IPDP), within which three phases with very well-defined activities and distinct focuses are listed. The first one where the functions to be delivered to the final consumer are discussed, evaluated and defined, the second where solutions that meet all project requirements are discussed and defined and the third where the specifications, simulations and tests are elaborated.

Therefore, in an extended planning horizon, with well-defined stages within each phase, more simultaneity in activities is allowed, making decisions collegiate. However, the checkpoint concepts that are applied in many companies can make the decision-making process purely linear. This extreme linearity ends up resulting in missed opportunities and limited ability to adapt to the inevitable changes in scenarios that occur in any type of development. Thus, as far as possible, the flow of information about decisions should occur in both directions of the IPDP [32].

Thus, more than a name for each stage, phase and stage, this chapter aims to discuss the content of this information and reflect on the flow of this information within the IPDP. More specifically, when issues related to the added value of functions are discussed during design and when solutions that generate specific costs for their industrialization are defined.

The chapter basis are the activities that happen at the boundary between conceptual design and preliminary design. Throughout these stages, links are structured between the value evaluation of the added functions and the cost generated by the choice of solutions. Figure 3 shows the limits of this study. Throughout the great journey that defines the product lifecycle, the study focuses on the development phase. Within the development, the frontier of the study is highlighted in detail “A”, which involves the phases of definition of functions and solutions that are made during the conceptual and preliminary project. Detail “B” of the Figure 3 represents the control volume in which the method proposed in this article is found. Where iterations are proposed between the conceptual and preliminary design phases, aiming to balance value and cost in an integrated and simultaneous way in an engineering environment.

Figure 3.

Defining the location of research in a product’s life cycle.

To summarize, in the IPDP, the starting point is always a requirements analysis. Afterwards, this analysis is used in a conceptual design, that is, to develop a concept that meets the requirements through functions. From this moment on, the selected concept is designed in order to create maps of possible solutions throughout the preliminary design. After the best combination and solutions are selected, the design is detailed.

The method proposed in this chapter is located at the frontier of the functions definition and solutions definition phases of a new develop. For this, it uses value engineering and cost analysis as a link between these phases. Thus, these concepts will be presented below for a better understanding of the method.

5. Proposal for a model oriented to the balance between value and cost - DFB

The generation of alternative solutions for the same functions is a central element in product design. The search for solutions using morphological matrices explores and encourages the multidisciplinary development group to identify new combinations of principles for existing solutions. Ma et al. [33] argues that the use of the morphological matrix can help the project team to organize the process of generating and combining solutions. Thus, the rationalization of the creative process at this stage lies in the organization of the proposed solutions. In this sense, and supported by a progressive, iterative and integrated ideal defended by the main authors of the systematic literature review, the traditional concept of DFA can be considered as a philosophy of the preliminary project that will serve as a link for the consolidation of the proposed method. This systematization proposal, philosophically, will guide stakeholders to define an ideal number of parts and assembly combinations that optimize material expenditure and the future production process. Always trying to balance the value of the functions with the costs of the solutions.

Bibliographic analyzes showed that the cyclical tools between the functions definition phases and the solutions definition phases are still in an intermediate stage of development [13], making the proposal addressed in this research of significant importance in the initial stages of creating a new product. Thus, [34] proposed an integrated product development method based on CE and DFA, called DFB, from the English acronym “Design for Balance”. This method suggests carrying out iterations between the development phase that studies the value of functions (traditionally called conceptual design) and the design phase that studies the solutions for each function (traditionally called preliminary design). If the sum of the modules of the differences between values and costs of all functions is equal to zero, we would have an ideal project. Eq. (1) proposes this goal of perfection. In it, “V” represents the percentage value of each analyzed function and “C” represents the percentage cost to produce each of these functions. That would be a utopianly perfect project. Thus, the proposal of the method is to seek combinations of solutions that approximate, as much as possible, the result of this equation to zero. After all, when the sum of the difference modules was equal to zero, the perfect balance between value and cost of all functions in the studied set would be reached.

$$\sum _{i=1}^n\left|V_i-C_i\right|\to 0$$E1

To achieve this approach, the method proposes iterations between the design phase that studies the value of functions (traditionally called conceptual design) and the design phase that studies solutions for each function (traditionally called preliminary design). In an ideal project, the sum of the differences in values and costs of all functions, in modulus, should be zero. The equation below illustrates this objective, where V is the percentage value of each function and C the percentage cost of each function. As this is utopian, the objective of the method is to bring the result of this equation as close as possible to zero, as proposed in eq. (1).

To carry out the evaluation of the method, [35] presented and tested a proposed method with the five steps described below, as summarized conceptually in Figure 4.

Figure 4.

Concept-based on Fibonacci spiral [3, 35].

The method’s intention is to organize the decision-making process, so that ideas can go beyond the involuntary stimuli throughout the developmental routine and become stimulated throughout the application of the method in a systematized way. The proposal is composed of five steps, as step by step below:

Step 1 - Definition of mechanical assemblies: The assemblies must be chosen in view of the greater potential of cost reduction in raw material, without reducing quality, as well as those that present many assembly operations or logistical movements during the industrialization process.

Step 2 - Definition of value engineering strategies: The analysis on the use of VE tools will have the purpose of identifying the recommendations for the improvement of solutions that aim at balancing the functions listed in the value x cost chart. The “value” data, which are the percentage levels of importance perceived by the consuming public, will come from the Mudge diagram. On the other hand, the data on the “costs” of the same functions will come from the matrix of cost reduction.

Step 3 - Functions cost analysis: At this stage, the cost analysis of the functions is carried out by the multidisciplinary design team that should discuss the costs of each function and the application of DFA methods in product development.

The analysis of the results shows that the function determined as the main function in the previous step has a higher percentage of cost since it is perceived by the consumer as the most relevant and concentrates the development team’s improvement efforts. This cost-rate matrix allows to visualize and understand the cost of each function and the possible impact on product development and reflecting the product success.

Step 4 – Balance check: value x cost: The reduction of any uncertainties in the processes of creation and selection of concepts and functions is necessary to map the boundary conditions associated with the design problem. In this Step, a new table is created, and the functions listed on the horizontal axis and the cost percentages are presented on the vertical axis. Thus, the percentage value derived from the Mudge diagram calculated in Step 2 and the percentage cost derived from the cost allocation calculated in Step 3 can be compared function by function.

The comparison results also highlight which functions have the greatest potential for improvement in terms of equilibrium “value” x “cost”. It is worth noting that if an isolated function has a percentage cost higher than its importance, other functions will pay this percentage. Next, the model equation is applied to the difference between the functions and cost, resulting in a percentage showing this relationship’s state within the product design. This result reveals the design balance level, and the more the result tends to zero, the more balanced is the design.

The sum of all difference modules between the value and cost percentages provides an indicator that compares the new solution combinations proposals. Therefore, the multidisciplinary product development team’s actions will focus on optimizing the solutions combinations proposals and the balance of the design.

Step 5 – DFA application: For the practical application of the DFA concepts, it will initially be necessary to create a multidisciplinary team with representatives of product engineering, industrial design, logistics and manufacturing, who can work together in all decision making. This requirement should be met through in-person meetings.

The DFA methods aim to improve the project, looking for shorter times and costs; thus, this activity will use methods that allow the number of components involved in each assembly to be minimized, and verifying the real need of each one. As a case, the Boothroyd-Dewhurst method (Boothroyd, 2001) was used, in which three simple questions are proposed verifying the real necessity of a component:

1. Does the piece, component or part under analysis have movements related to its surroundings?

2. Does the piece, component or part under analysis require a different material for its function/functionality?

3. Does the piece, component or part under analysis need to be disassembled/removed for the repair of another one?

If all the answers are “NO”, we can propose the unification of components and materials for reducing the cost of raw material and labor.

This step’s objective is to verify the most viable configuration in terms of the balance between the “value” and the “cost” of the functions and the lower final cost, considering all the industrial impacts of the proposal in the context of DFA concepts application. The multidisciplinary team analyses the previous step results based on the principle that the design is balanced when the sum of all difference modules between the functions value and cost percentages is equal or close to zero. Next, using DFA concepts proposes a new solution with fewer parts and assemblies, leading to a new material and labor costs chart and, consequently, a new cost-per-function rate matrix.

At this point, the model proposes a further verification of the potential opportunities for improvement and innovation of solutions so that a new product could perform its activities at a lower cost and with the largest scale of perceived value. The model indicates the repetition of steps 4 and 5 at least once, but with as many repetitions as necessary, according to the product’s design team definitions and objectives.

The proposed model aimed to encourage the project team to work in an integrated way, systematizing the creative process. With this, increasing the chances of including new opportunities throughout the conceptual and preliminary development and seeking innovations in solutions, with lower cost, presenting the highest possible perceived value and in the shortest possible time. These steps were applied in home appliance industry cases, where excellent results were obtained. The results were positive both in the search for the balance between value and cost of the functions, as well as in the general reduction of material and labor costs of the studied subassemblies.

6. Application case of the model oriented to the balance between value and cost - DFB

In search of an exploratory study to verify the effectiveness of the method, this chapter used as a reference the optimization of the assembly time and the total cost of the solution for the hinge of an appliance to be produced on a large scale.

Figure 5 shows the parts involved in the original solution for this subset, as well as their respective costs of materials and transformation. For the set of solutions contained in the original production condition, a functional analysis was prepared, where the following functions of this set were listed:

Figure 5.

Home appliance hinge – Original solution.

Function A – Allow assembly with the product lying down;

Function B – Position and support the door;

Function C – Structuring Cabinet;

Function D – Level the product;

Function E – Slide the product easily;

Function F – Lock the product in the position of use;

Function G – Do not tip the product when the door is opened;

Function H – Enable door replacement for maintenance.

After defining the functions, as indicated by [35], the Mudge method was applied to analyze the value of the functions in terms of percentage importance. Which resulted in the diagram contained in Figure 6.

Figure 6.

Mudge diagram applied to the hinge assembly.

With the functions defined, we started to list and quote the parts, as well as the cost of assembly or transformation (DL) of the original version, as indicated in Table 2.

PARTS		COSTS (R$)
	Direct Labor Cost (DL)	5.55
1	Body - Material: 4 mm steel	5.15
2	“U” profile - Material: 4 mm steel	3.30
3	“U” profile - Material: 1,5 mm steel	0.95
4	Threaded base - Material: injected Al	4.60
5	Roller - Material: Nylon	2.55
6	Leveling foot (Sneaker) - Material: Polyacetal	3.60
7	Roller pin - Material: commercial	0.55
8	Screws - Material: commercial	0.20
	TOTAL (R$)	26.45

Table 2.

Original assembly parts list and quotation.

With the parts list formalized and with the respective quotations, it was possible to apply the cost apportionment method to analyze the absolute and percentage cost of each function, through the transposition of the costs of the parts in costs of functions. For this, we used the cost apportionment method described by [35], which resulted in the apportionment matrix shown in Figure 7.

Figure 7.

Cost apportionment of the original version.

With the results of the Mudge Diagram and the Cost Sharing Matrix, it is possible to define the Value x Cost comparison chart of the original product concept, shown in Figure 8. To build this chart, the functions were listed on the horizontal axis and the percentages, both of value and of costs, were presented on the vertical axis. Thus, the percentage value, derived from the Mudge diagram, and the percentage cost, derived from the cost breakdown, can be compared function by function.

Figure 8.

Value x cost chart of original hinge assembly solution.

It can be seen, then, that with this combination of original solutions, there is a significant distance between value and costs in some functions, such as C, D, E, F, G and H. Adding the modules of the differences between value and cost of all functions, we arrive at 59.2. %, as shown in Figures 7 and 9.

Figure 9.

Solution and costing after the first iteration. Value x cost graph of the solution after the first iteration.

The information in this diagram made it possible to trigger Design, Engineering and Manufacturing actions aimed at optimization and balance. It is important to point out that as the functions remain the same to meet the requirements, the value graph does not change and all percentage movements must occur with each new cost proration generated by new solution proposals.

As recommended in the method presentation, the next step was to use DFA strategies in order to seek this optimization of solutions. To this end, the three classic questions were proposed for each component: i) Does the component or assembly being analyzed move in relation to the other parts in contact?; ii) Does the component or assembly being analyzed require a different material type in order to function?; and iii) Should the component or assembly being analyzed be dismantled or removed in any case of use? In this case, as they had parts assembled with all three “NO” answers, it was possible to suggest the unification of the parts, aiming to reduce costs of both raw material and labor for transformation, as shown in Figure 9, where the combination of solutions resulted in a cost reduction of R$ 4.35, that is, savings of 16%, with the perceived quality.

Comparing the graphs of the original solution (Figure 8) with those of the solution after the first iteration of the method (Figure 9), we can observe the approximation of the value and cost points by function. It is observed that the sum of the modules of the differences between value and cost has decreased, which increases the balance between the perception of value and the cost of industrialization.

With this first iteration, the results achieved have already shown a great improvement in the final cost. However, the proposed method suggests at least two iterations or iterations until the sum of the module of the differences between value and cost is less than 20% or when the DFA strategies no longer generate all negative answers for the three standard questions [13].

Thus, the three questions were applied again, at the end of which a new solution proposal never presented in previous discussions was reached. In this new design, a new improvement in cost results can be observed - a reduction of R$ 7.15, in relation to the original proposal, which represented a savings, now, of 27%, compared to the original solution.

However, more than the global cost reduction, there was a great approximation between the points of the value and cost graphs, function by function, as shown in Figure 10. Thus, through the comparisons of value x observed cost graphs in Figure 10, observing the three proposals tested, it is noted that the third - after the second round of DFA - was balanced due to the greater proximity of the points of each function. In addition to this clear better balance, it also resulted in a lower final cost.

Figure 10.

Comparison of solutions, costs and comparatives value x cost of the original proposal and the proposals after the iterations.

Still in Figure 10, it can be seen that, as the functions do not change, their value graphs remain unchanged regardless of the applied solution. Thus, the cost graphs are adjusted by the points approach, function by function, where the sum of the differences of the value and cost percentage modules dropped from 59.2%, in the original version, to 34.0% after the first iteration and finally 18.1% after the second round of application of the DFA strategies, as foreseen in the proposed model. In addition to this balance achieved, another great gain came in the total cost of the solution, with a total drop of 27% at the end of the application of the proposal.

7. Considerations about the proposed DFB method

This chapter evaluated an integrated product development method that integrates the conceptual design and preliminary design phases. In order to seek a balance between the value perceived by internal and external customers for each of the functions of a set, with the cost of generated by the combination of solutions that meet these functions a new consumer good or part of it.

In this sense, the relevance of providing the multidisciplinary group of projects, which works in an integrated environment and simultaneously, with information on costs during the process of defining the solutions, to feed back the information of the conceptual design, seeking the balance value and cost. After all, the success or failure of the product in the field is largely determined by the initial development decisions. Thus, designers, engineers, represented in the areas of marketing, commercial, among others, must know the costs incurred in the phases subsequent to their decisions, and contribute to this search for balanced solutions, in order to meet their demands.

The model evaluated allowed the alternatives generated to solve the problems to be evaluated, stimulating the search for design alternatives, aimed at a balanced development between value and cost, while taking into account the requirements of the most diverse areas involved throughout the development product life cycle, including Marketing, Design, Product Engineering, Manufacturing, Logistics, Quality, Sales and Technical Assistance. Ensuring maximum service to your needs and committing the entire group to the product under development throughout its life cycle.

As a result, analyzing quantitatively, a total reduction of R$ 7.15 per product was observed. This means a direct savings of 27% in the final solution achieved when compared to the original combination. The verification of the costs in each round of the model application can be seen in Figure 10. In it is clear the importance and the gain of opportunities brought by the method. However, in addition to this quantitative analysis of the general costs, it was possible to observe a qualitative improvement in terms of the balance between the value and the cost of each function in the comparison of each cycle of application of the method. Still in Figure 10, it can be seen that the sum of the differences in the value and percentage of the cost, function by function, decreased with each iteration. In general, it is clear that the proposed method has significant qualitative advantages, as a better balance between value and cost increases the probability of project success. Likewise, the quantitative gains for this product are clear when considering an annual production of 200,000 units. Because, with this individual cost reduction of BRL 7.15 per product, annual savings of around BRL 1,430,000.00 are achieved just with this action in this specific subset.

As only a portion of the product was analyzed, further reductions in this family of consumer goods can be expected by expanding this analysis to other groups of parts and assemblies.

As a suggestion for possible future work, the model presented could be applied and validated in other product development models or even other types of productive organizations. Among these types, we could mention the automotive, cosmetics, food industries, among others. Other possible points of evaluation would be the analysis of the effect of applying this model on the other two supports of the economic-environmental-social triple bottom line, since the focus of this study was concentrated on the economic effects. After all, these changes in solutions also generated changes in materials and the ways in which people would interact with the product throughout its chain, from suppliers, through the assembly processes, to interactions with the final customer.