Concept Development: The Front-End Process

Because the concept development phase of the development process demands perhaps more coordination among functions than any other, many of the integrative development methods presented in this book are concentrated here. In this section we expand the concept development phase into what we call the front-end process. The front-end process generally contains many interrelated activities, ordered roughly as shown in Exhibit 2-3. Rarely does the entire process proceed in purely sequential fashion, completing each activity before beginning the next. In practice, the front-end activities may be overlapped

in time and iteration is often necessary. The dashed arrows in Exhibit 2-3 reflect the uncertain nature of progress in product development. At almost any stage, new information may become available or results learned which can cause the team to step back to repeat an earlier activity before proceeding. This repetition of nominally complete activities is known as development iteration.

The concept development process includes the following activities:

• Identifying customer needs: 

The goal of this activity is to understand customers' needs and to effectively communicate them to the development team. The output of this step is a set of carefully constructed customer need statements, organized in a hierarchical list, with importance weightings for many or all of the needs. A method for this activity is presented in Chapter 4, Identifying Customer Needs.

• Establishing target specifications: 

Specifications provide a precise description of what a product has to do. They are the translation of the customer needs into technical terms. Targets for the specifications are set early in the process and represent the hopes of the development team. Later these specifications are refined to be consistent with the constraints imposed by the team's choice of a product concept. The output of this

stage is a list of target specifications. Each specification consists of a metric, and marginal and ideal values for that metric. A method for the specification activity is given in Chapter 5, Product Specifications.

• Concept generation: 

The goal of concept generation is to thoroughly explore the space of product concepts that may address the customer needs. Concept generation includes a mix of external search, creative problem solving within the team, and systematic exploration of the various solution fragments the team generates. The result of this activity is usually a set of 10 to 20 concepts, each typically represented by a sketch and brief descriptive text. Chapter 6, Concept Generation, describes this activity in detail.  

• Concept selection: 

Concept selection is the activity in which various product concepts

are analyzed and sequentially eliminated to identify the most promising concept(s).

The process usually requires several iterations and may initiate additional concept generation

and refinement. A method for this activity is described in Chapter 7, Concept

Selection.

• Concept testing: One or more concepts are then tested to verify that the customer needs have been met, assess the market potential of the product, and identify any shortcomings which must be remedied during further development. If the customer response is poor, the development project may be terminated or some earlier activities may be repeated as necessary. Chapter 8, Concept Testing, explains a method for this

activity.

• Setting final specifications: 

The target specifications set earlier in the process are revisited after a concept has been selected and tested. At this point, the team must commit to specific values of the metrics reflecting the constraints inherent in the product concept, limitations identified through technical modeling, and trade-offs between cost and performance.Chapter 5, Product Specifications, explains the details of this activity.

• Project planning: 

In this final activity of concept development, the team creates a detailed development schedule, devises a strategy to minimize development time, and identifies the resources required to complete the project. The major results of the front-end activities can be usefully captured in a contract book which contains the

mission statement, the customer needs, the details of the selected concept, the product specifications, the economic analysis of the product, the development schedule, the project staffing, and the budget. The contract book serves to document the agreement (contract) between the team and the senior management of the enterprise. A project planning method is presented in Chapter 16, Managing Projects.

• Economic analysis: 

The team, often with the support of a financial analyst, builds an economic model for the new product. This model is used to justify continuation of the overall development program and to resolve specific trade-offs among, for example, development costs and manufacturing costs. Economic analysis is shown as one of the

ongoing activities in the concept development phase. An early economic analysis will almost always be performed before the project even begins, and this analysis is updated as more information becomes available. A method for this activity is presented in Chapter 15, Product Development Economics.

• Benchmarking of competitive products: 

An understanding of competitive products is critical to successful positioning of a new product and can provide a rich source of ideas for the product and production process design. Competitive benchmarking is performed in support of many of the front-end activities. Various aspects of competitive benchmarking are presented in Chapters 4-8.

• Modeling and prototyping: 

Every stage of the concept development process involves various forms of models and prototypes. These may include, among others: early "proof-of-concept" models, which help the development team to demonstrate feasibility; "form-only" models, which can be shown to customers to evaluate ergonomics and style; spreadsheet models of technical trade-offs; and experimental test models, which can be used to set design parameters for robust performance.

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References and Bibliography

Many current resources are available on the Internet via

www.ulrich-eppinger.net

Stage-gate product development processes have been dominant in manufacturing firms

for the past 30 years. Cooper describes the modem stage-gate process and many of its

enabling practices.

Cooper, Robert G., Winning at New Products: Accelerating the Process from Idea to

Launch, third edition, Perseus Books, Cambridge, MA, 2001.

How Designers Think

In an experimental research study, Lawson (1984) compared the ways in which designers (in this case architects) and scientists solved the same problem. The scientists tended to use a strategy of systematically trying to understand the problem, in order to look for underlying rules which would enable them to generate an optimum solution. In contrast, the designers tended to make initial explorations and then suggest a variety of possible solutions until they found one that was good, or at least satisfactory.

The evidence from the experiments suggested that scientists problem-solve by analysis, whereas designers problem-solve by synthesis; scientists use 'problem-focused strategies' and designers use 'solution-focused strategies'.

Some other studies have also suggested that designers tend to use conjectures about solution concepts as the means of developing their understanding of the problem. Darke (1984) found that designers impose a primary generator onto the problem, in order to narrow the search space and generate early solution concepts.

This primary generator is usually based on a tightly-restricted set of constraints or solution possibilities derived from the design problem. Since 'the problem' cannot be fully understood in isolation from consideration of 'the solution', it is natural that solution conjectures should be used as a means of helping to explore and understand the problem formulation. Making sketches of solution concepts is one way that helps the designer to identify their consequences, and to keep the problem exploration going, in what Sch6n (1983) called the 'reflective conversation with the situation' that is characteristic of design thinking.

Drawing and sketching have been used in design for a long time, certainly since long before the Renaissance, but the period since that time has seen a massive growth in the use of drawings, as designed objects have become more complex and more novel. Many of Leonardo da Vinci's drawings of machines and inventions

from the Renaissance period show one of the key aspects of design drawings, in terms of their purpose of communicating to someone else how a new product should be built, and also how it should work. Some of Leonardo's design drawings also show how a drawing can be not only a communication aid, but also a thinking and reasoning aid. For example, Leonardo's sketches for the design of fortifications (Figure 7) show how he used sight-lines and missile trajectories as lines to set up the design of the fortifications, and how his design thinking was assisted by drawing. In such drawings we see how the sketch can help the designer to consider many aspects at once; we see plans, elevations, details, trajectory lines, all being drawn together and thus all being thought about, reasoned about, all together.

Half a millenium later, we still see designers using essentially  similar types of sketch to aid their design thinking. The early concept sketches for a house design by the contemporary architect Charles Moore (Figure 8) show similar kinds of representations as those used by Leonardo: plan, elevation and section all being

considered together with considerations of structure and calculations of dimensions and areas.

What might we learn about the nature of design thinking from looking at examples of what designers sketch? One thing that seems to appear is that sketches enable designers to handle different levels of abstraction simultaneously. Clearly this is something important in the design process. We see that designers think about the overall concept and at the same time think about detailed aspects of the implementation of that concept. Obviously not all of the detailed aspects are considered early on, because if they could do that, designers could go straight to the final set of detailed drawings. So they use the concept sketch to identify and then to reflect upon critical details, particular details that they realise might hinder or somehow significantly influence the final implementation of the complete design. This implies that, although there is a hierarchical structure of decisions, from overallconcept to details, designing is not a strictly hierarchical process; in the early stages of design, the designer moves freely between different levels of detail.

The identification of critical details is part of a more general facility that sketches provide, which is that they enable identification and recall of relevant knowledge. As the architect Richard MacCormac has said about designing, 'What you need to know about the problem only becomes apparent as you're trying to solve it.' There is a massive amount of information that may be relevant, not only to all the possible solutions for a

design problem, but simply to any possible solution. Any possible solution in itself creates the unique circumstances in which these large bodies of information interact, probably in unique ways for any one possible solution. So these large amounts of information and knowledge need to be brought into play in a selective way, being selected only when they become relevant, as the designer considers the implications of the solution concept as it develops. 

Because the design problem is itself ill-defined and ill-structured,

a key feature of design sketches is that they assist problem structuring through the making of solution attempts. Sketches incorporate not only drawings of tentative solution concepts but also numbers, symbols and text, as the designer relates what he knows of the design problem to what is emerging as a solution. Sketching enables exploration of the problem space and the solution space to proceed together, assisting the designer to converge on a matching problem-solution pair. Problem and solution co-evolve in the design process.

Designers' use of sketches therefore gives us some considerable insight into the nature of design thinking and the resolution of design problems. These problems cannot be stated sufficiently explicitly such that solutions can be derived directly from them. The designer has to take the initiative in finding a problem starting point and suggesting tentative solution areas. Problem and solution are then both developed in parallel, sometimes leading to a creative redefinition of the problem, or to a solution that lies outside the boundaries of what was previously assumed to be possible. 

Solution-focused strategies are therefore perhaps the best way of tackling design problems, which are by nature ill-defined. In order to cope with the uncertainty of ill-defined problems, the designer has to have the self-confidence to define, redefine and change the problem as given, in the light of solutions that emerge

in the very process of designing. People who prefer the certainty of structured well-defined problems will never appreciate thedelight of being a designer!

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Engineering Design Methods

Strategies for Product Design

THIRD EDITION

Nigel Cross

The Open University, Mi/ton Keynes, UK

JOHN WILEY & SONS, LTD

Chichester- New York. Weinheim • Brisbane. Singapore. Toronto

Materials Selection

As stated earlier, the selection of a material for a machine part or  structural member is one of the most important decisions the designer is called on to make. Up to this point in this chapter we have discussed many important material physical properties, various characteristics of typical engineering materials, and various material production

processes. The actual selection of a material for a particular design application can be an easy one, say, based on previous applications (1020 steel is always a good candidate because of its many positive attributes), or the selection process can be as involved and daunting as any design problem with the evaluation of the many material physical, economical, and processing parameters. There are systematic and optimizing approaches to material selection. Here, for illustration, we will only look at how to approach some material properties. One basic technique is to list all the important material properties associated with the design, e.g., strength, stiffness, and cost. This can be prioritized by using a weighting measure depending on what properties are more important than others. Next, for each property, list all available materials and rank them in order beginning with the best material; e.g., for strength, high-strength steel such as 4340 steel should be near the top of the list. For completeness of available materials, this might require a large source of material data. Once the lists are formed, select a manageable amount of materials from the top of each list. From each reduced list select the materials that are contained within every list for further review. The materials in the reduced lists can be graded within the list and then weighted according

to the importance of each property.

M. F. Ashby has developed a powerful systematic method using materials selection charts.16 This method has also been implemented in a software package called CES Edupack.17 The charts display data of various properties for the families and classes of materials listed in Table 2–4. For example, considering material stiffness properties, a simple bar chart plotting Young’s modulus E on the y axis is shown in Fig. 2–15. Each vertical line represents the range of values of E for a particular material. Only some of the materials are labeled. Now, more material information can be displayed if the x axis represents another material property, say density.

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Mechanical Engineering

McGraw−Hill Primis

ISBN: 0−390−76487−6

Text:

Shigley’s Mechanical Engineering Design,

Eighth Edition

Budynas−Nisbett

The six phases of the generic development process

The generic product development process consists of six phases, as illustrated in

Exhibit 2-2. The process begins with a planning phase, which is the link to advanced research and technology development activities. The output of the planning phase is the project's mission statement, which is the input required to begin the concept development phase and which serves as a guide to the development team. The conclusion of the product development process is the product launch, at which time the product becomes available for purchase in the marketplace. One way to think about the development process is as the initial creation of a wide set of alternative product concepts and then the subsequent narrowing of alternatives and increasing specification of the product until the product can be reliably and repeatably produced by the production system. Note that most of the phases of development are defined in terms of the state of the product, although the production process and marketing plans, among other tangible outputs, are also evolving as development progresses.

Another way to think about the development process is as an information-processing system. The process begins with inputs such as the corporate objectives and the capabilities of available technologies, product platforms, and production systems. Various activities process the development information, formulating specifications, concepts, and design details. The process concludes when all the information required to support production and sales has been created and communicated.

A third way to think about the development process is as a risk management system. In the early phases of product development, various risks are identified and prioritized. As the process progresses, risks are reduced as the key uncertainties are eliminated and the functions of the product are validated. When the process is completed, the team should have substantial confidence that the product will work correctly and be well received by the market.

Exhibit 2-2 also identifies the key activities and responsibilities of the different functions of the organization during each development phase. Because of their continuous involvement in the process, we choose to articulate the roles of marketing, design, and  manufacturing. Representatives from other functions, such as research, finance, field service, and sales, also play key roles at particular points in the process.

The six phases of the generic development process are:

o. Planning: The planning activity is often referred to as "phase zero" since it precedes the project approval and launch of the actual product development process. This phase begins with corporate strategy and includes assessment of technology developments and market objectives. The output of the planning phase is the project mission statement, which specifies the target market for the product, business goals, key assumptions, and constraints. Chapter 3, Product Planning, presents a discussion of this planning process.

1. Concept development:

In the concept development phase, the needs of the target market are identified, alternative product concepts are generated and evaluated, and one or more concepts are selected for further development and testing. A concept is a description of the form, function, and features of a product and is usually accompanied by a set of specifications, an analysis of competitive products, and an economic  justification of the project. This book presents several detailed methods for the concept development phase (Chapters 4-8). We expand this phase into each of its constitutive activities in the next section.

2. System-level design: 

The system-level design phase includes the definition of the product architecture and the decomposition of the product into subsystems and components. The final assembly scheme for the production system is usually defined during this phase as well. The output of this phase usually includes a geometric layout of the product, a functional specification of each of the product's subsystems, and a preliminary process flow diagram for the final assembly process. Chapter 9, Product Architecture, discusses

some of the important activities of system-level design. 

3. Detail design: 

The detail design phase includes the complete specification of the geometry, materials, and tolerances of all of the unique parts in the product and the identification of all of the standard parts to be purchased from suppliers. A process plan is established and tooling is designed for each part to be fabricated within the production system. The output of this phase is the control documentation for the product-the drawings

or computer files describing the geometry of each part and its production tooling,

the specifications of the purchased parts, and the process plans for the fabrication and assembly

of the product. Two critical issues addressed in the detail design phase are production

cost and robust performance. These issues are discussed respectively in Chapter 11,

Design for Manufacturing, and Chapter 13, Robust Design.

4. Testing and refinement: 

The testing and refinement phase involves the construction

and evaluation of multiple preproduction versions of the product. Early

(alpha) prototypes are usually built with production-intent parts-parts with the same

geometry and material properties as intended for the production version of the product

but not necessarily fabricated with the actual processes to be used in production.

Alpha prototypes are tested to determine whether the product will work as designed

and whether the product satisfies the key customer needs. Later (beta) prototypes are

usually built with parts supplied by the intended production processes but may not be

assembled using the intended final assembly process. Beta prototypes are extensively

evaluated internally and are also typically tested by customers in their own use environment.

The goal for the beta prototypes is usually to answer questions about performance

and reliability in order to identify necessary engineering changes for the final

product. Chapter 12, Prototyping, presents a thorough discussion of the nature and use

of prototypes.

5. Production ramp-up: In the production ramp-up phase, the product is made using

the intended production system. The purpose of the ramp-up is to train the work force

and to work out any remaining problems in the production processes. Products produced

during production ramp-up are sometimes supplied to preferred customers and are carefully

evaluated to identify any remaining flaws. The transition from production ramp-up

to ongoing production is usually gradual. At some point in this transition, the product is

launched and becomes available for widespread distribution.

READ MORE.......

References and Bibliography

Many current resources are available on the Internet via

www.ulrich-eppinger.net

Stage-gate product development processes have been dominant in manufacturing firms

for the past 30 years. Cooper describes the modem stage-gate process and many of its

enabling practices.

Cooper, Robert G., Winning at New Products: Accelerating the Process from Idea to

Launch, third edition, Perseus Books, Cambridge, MA, 2001.