Product design for modularity

Relationships Between Components' Functions Analysis Results for the Existing Design and Alternative Design 1162 Analysis Results for the Existing Design and Alternative Design 2163 Anal

Product Design for Modularity

Second Edition

PRODUCT DESIGN FOR MODULARITY

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DOI 10.1007/978-1-4757-3581-9

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Copyright © 2002 by Springer Science+Business Media New York

Originally published by Kluwer Academic Publishers in 2002

Softcover reprint ofthe hardcover 2nd edition 2002

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Chapter 1: Product Development Process: An Introduction

I The Evolution ofProduct Development

2 The Importance ofProduct Development

3 Sequential Product Development

4 Simultaneous/lntegrated Product Development

5 Generic Product Development Process

6 Product Development Categories

7 Case Studies

Chapter 2: Modular Design

I Modularity Types

2 Modular Systems Characteristics

3 Modular Systems Development

vii

IX

xiii

xv xvii

2 Appendix A: Engineering Design Speeifieations

Chapter 5: Design for Manufaeture and Assembly

1 DFMA Methodology

2 Case Study: DFA Analysis ofa Fog Lamp Design

3 Geometrie and Parametrie Design

4 Design for Manufaeture

5 Strueture for a Template-based System

6 Appendix A: Crankshaft Parametrie File Strueture

7 Appendix B: Formulation used for Material Removal

8 Appendix C: SampIe Proeess Plan

Chapter 6: Flexible and Modular Cell Design

1 Traditional Manufaeturing Systems-An Overview

2 Cellular Manufaetuimg Systems

3 Cellular Manufacturing Systems Design

List of Figures

Figure 1 Design for Modularity Life Cycle xix

Figure 1.1 Sequential Product Development 4

Figure 1.2 SimultaneouslIntegrated Product Development 5

Figure 1.3 Product Development Process 6

Figure 1.5 Parametrie Analysis Plot 9

Figure 1.7 Establishing Design Specifications 11

Figure 1.8 Needs-Metrics Matrix 12

Figure 1.9 Concept Generation 13

Figure 1.10 Concept Selection 14

Figure 1.12 Single-Use Camera 20

Figure 1.13 Single-use Camera Needs Interpretation 22

Figure 1.14 Single-use Camera Matrix Analysis 22

Figure 1.15 Needs Prioritization Survey 24

Figure 1.17 SunroofNeeds-Metrics Matrix 26

Figure 1.18 Sunroof Competitive Benchmarking 27

Figure 1.19 Sunroof Initial Specifications 27

Figure 1.21 Paper Clip Function 29

Figure 1.22 Paper Clip Detailed Functions 29

Figure 1.23 Paper Clips - Market Study 30

Figure 1.24 Paper Clips - Patent Material 30

Figure 1.25 Design Seetions ofPaper Clip 31

x List o[ Figures

Figure 1.34 Paper Clip Conceptual Design 34

Figure 1.36 Piston-Connecting Rod- Crankshaft Assembly 35

Figure 1.37 Connecting Rod Design Feature Names 37

Figure 1.38 Connecting Rod Design Details 38

Figure 1.39 Partial Cross Section ofConnecting Rod and Crank Pin Journal 39

Figure 1.40 Connecting Rod Virtual Prototype 39

Figure 1.41 SampIe Crankshaft Template 40

Figure 1.42 Crankshaft Generic Process Plan - Partial 41

Figure 1.43 Machine selection procedure 43

Figure 1.44 Machine layout - Partial 44

Figure 2.1 Function and Module Types 47

Figure 2.2 Component-Swapping Modularity 49

Figure 2.3 Component-Sharing Modularity 49

Figure 2.4 Fabricate-to-Fit Modularity 50

Figure 2.6 PC Assembly Diagram 52

Figure 2.7 Structural Decomposition ofa VehicIe System 52

Figure 2.8 Structural Decomposition of a Carriage Unit 53

Figure 2.9 Requirements Decomposition 54

Figure 2.10 Ball Bearing Design Constraint-Parameter Incidence Matrix 55

Figure 2.11 Decomposed Constraint-Parameter Incidence Matrix 56

Figure 2.12 Hierarchical Decomposition of a Complex System 56

Figure 2.13 Monocode Structure 59

Figure 2.14 Polycode Structure 59

Figure 2.16 Part-Machine Incidence Matrix 61

Figure 2.17 Information Dependency Types 73

Figure 2.19 Lower Triangular DSM 78

Figure 2.20 Block Triangular DSM 79

Figure 2.21 Decoupling to Speed Design 81

Figure 2.22 Coupling to Improve Quality 82

Figure 3.1 Overview of the Proposed Design Environment 85

Figure 3.2 Design for Modularity 87

List 01 Figures xi

Figure 3.3 Customer Satisfaction Process 88

Figure 3.5 The House of Quality 94

Figure 3.6 Function-Structure Diagram 102

Figure 3.7 Computer Physical Decomposition 102

Figure 3.8 Overall Function Flow Diagram 104

Figure 3.9 Function Flow Diagram 104

Figure 3.10 System-Level Specification Decomposition Hierarchy 106

Figure 3.11 Basic structure of a genetic algorithm 111

Figure 4.2 Four-Gear Speed Reducer 127

Figure 4.3 Physical Decomposition ofPump System 127

Figure 4.4 Overall Function ofthe Speed Reducer 128

Figure 4.5 Components' Functions 128

Figure 4.6 System-Level Specification Hierarchy Structure 130

Figure 4.7 Functional Similarity Matrix 132

Figure 4.8 Physical Similarity Matrix 133

Figure 4.9 Combined Similarity Matrix 133

Figure 4.10 Functional Modules 134

Figure 4.11 Physical Modules 134

Figure 4.12 Combined Modules 135

Figure 4.14 GA response for two-modules solution 136

Figure 4.15 Grouping for a two modules 137

Figure 4.16 GA response for a three-modules solution 138

Figure 4.17 Grouping for a three-group solution 138

Figure 4.18 Grouping for a four-module solution 139

Figure 4.19 Summary results ofthe GA run 139

Figure 5.2 Traditional Process vs Concurrent Engineering Process 145

Figure 5.3 The Subtract and Operate Procedure 147

Figure 5.4 Paper Clip Example 147

Figure 5.5 DFMA Functional Criteria Flowchart 148

Figure 5.6 Original Arm Bracket Assembly 149

Figure 5.7 DFMA-Designed Arm Bracket Assembly 149

Figure 5.8 Design for Manual Assembly Worksheet 150

Figure 5.9 a and ß symmetry 151

Figure 5.10 Sampie analysis of size and thickness of parts 151

Figure 5.11 Manual Handling-Estimated Times (seconds) 152

Figure 5.12 Manual Insertion-Estimated Times (seconds) 153

Figure 5.13 Exploded View ofFog Lamp (current design) 155

Figure 5.14 Assembly Sequence ofCurrent Fog Lamp Design 156

Figure 5.15 Functionality Tables for Fog Lamp Design 160

XIl List 0/ Figures Figure 5.16 Exploded View ofFog Lamp (proposed design) 162

Figure 5.17 Alternative Design 1 163

Figure 5.18 Alternative Design 2 163

Figure 5.19 Alternative Design 3 164

Figure 5.20 Geometrie Modeling Classification 165

Figure 5.22 CAPP Characteristics 172

Figure 5.23 Integrated Product Design and Process Planning 173

Figure 5.25 Surfaces that Require Machining 177

Figure 5.26 General Crank Dimensions 179

Figure 5.28 Oil Hole Coordinate System 180

Figure 5.29 Counterweight Dimensions 180

Figure 5.30 Lightening Hole Dimensions 181

Figure 5.31 Balance Hole Dimensions 181

Figure 6.1 The Three Kinds ofTraditional Manufacturing Systems 190

Figure 6.2 Layouts ofManned and Unmanned Cells 192

Figure 6.3 The Dendrogram Constructed for Sampie Parts 209

Ball Bearing Design Parameters

Ball Bearing Design Constraints

Machines Combined Similarity Methods

Functional Objectives

Operational Functional Requirements

Relationships between Component Functions

GFRvs SLS

Basic Crossover Methodologies

Basic Mutation Methodologies

Relationships Between Components' Functions

Analysis Results for the Existing Design and Alternative Design 1162 Analysis Results for the Existing Design and Alternative Design 2163 Analysis Results for the Existing Design and Alternative Design 3164 Product-to-Process Features Associativities 166

Sampie GD&T and Process Machines Associativity

Overview ofV-CAPP and G-CAPP Characteristics

168

171 CAPP Systems Development Techniques 172 Characteristics of Cellular vs Traditional Manufacturing Systems 192

Coding of a Sampie Part with KAMCODE 196

xiv List ofTables

Table 6.5 Sampie Parts Used for Dissimilarity Analysis 199

Table 6.6 Dissimilarity Measures for Two Parts 199

Table 6.7 Disagreement Measures between All Parts 209

Table 6.8 Machine Investment Costs, Annual Available Machine Time,

Tool Investment Cost, and Tool Life 210

Table 6.9 Annual Demand for Various Parts (d,) 210

Table 6.10 Machine Reliability (R) 211

Table 6.11 Cell Configuration 211

Table 6.12 Number ofMachine Types and Their Assignments 212

Table 6.13 Number ofTool Types and Their Assignments 212

Acknowledgements

Ali Kamrani's students in the industrial, manufacturing, and engineering management programs at the College of Engineering and Computer Science, University of Michigan-Dearborn; and Gary Folven, Carolyn Ford, Roberts Apse and Corinne D'Italia of Kluwer Academic Publishers for giving us the opportunity to fulfill and continuously improve this book

Preface

The current marketplace is undergoing an accelerated pace of change that challenges corporations to innovate new techniques to respond rapidly to an ever-changing environment At the center of this changing environment is a new generation of empowered buyers (customers) equipped with fast-evolving technologies that allow them to buy from markets scattered across the globe Empowering the customers has deprived organizations of what was once their right-to introduce new products slowly, at their own leisure Organizations used to introduce new products every few years, and, for the most part, products offered limited functionalities and features A low-priced quality product-irrespective of customer satisfaction-was a guaranteed ticket for success

New global economies and global markets changed business practices and focused on the customer as the major player in the economy Organizations now fail or succeed based upon their ability to respond quickly to changing customer demands and to utilize new technological innovations In such an environment, the advantage goes to the firm that can offer greater varieties of new products with higher performance and greater overall appeal In order to compete in this fast-paced global market, organizations need to produce products that can be easily configured to offer distinctive capabilities compared to the competition Furthermore, organizations need to develop new methods and techniques to react rapidly

to required changes in products and market trends and to shorten the product development cycle, which will enable them to gain more economic competitiveness This requires that the tasks needed to develop products be made in parallel, starting at the early stages of product development By developing such techniques, organizations will be able rapidly to design

Modular products are products that fulfill various overall functions through the combination of distinct building blocks or modules, in the sense that the overall function performed by the product can be divided into sub-functions that can be implemented by different modules or components An important aspect of modular products is the creation of a basic core unit to which different components (modules) can be fitted, thus enabling a variety

of versions of the same module to be produced The core should have sufficient capacity to cope with all expected variations in performance and usage Components used in a modular product must have features that enable them to be coupled together to form a complex product

Designing a modular product can be done by using conventional product development techniques, but using these techniques will not lead to a reduction in product development lead time, and thus a new development methodology is needed that can utilize the full strength of the modular architecture of products Using the concept of modularity in product design focuses on decomposing the overall design problem into functionally independent sub-problems, in which interaction or interdependence between sub-problems is minimized Thus, a change in the solution of one problem may lead to a minor modification in other problems, or it may have no effect

on other sub-problems That is, the modular design concept attempts to establish a design decomposition technique that reduces the interaction between design components (or modules) to reduce the complexity and development time of a product

Thus, a modular design may be defined as one that decomposes a design problem into parts that are as independent from one another as possible A modular design usually is adaptable with little or no modification for many applications Modular design can also be viewed as the process of first producing units that perform discrete functions, then connecting the units together to provide a variety of functions Modular design emphasizes the minimization of interactions between components, enabling components to

be designed and produced independently from each other Each component designed for modularity is supposed to support one or more functions When components are structured together to form a product, they will support a larger or general function This shows the importance of analyzing the

Preface XIX

product function and decomposing it into sub-functions that can be satisfied

by different functional modules

Modularity can apply to production systems, where it aims at building production systems from standardized modular machines The fact that a wide diversity of production requirements exists has led to the introduction

of a variety of production machinery and a lack of agreement on what the building blocks should be This means that there are no standards for modular machinery In order to build a modular production system, production machinery must be classified into functional groups from which the selection of a modular production system can be made to respond to different production requirements

This book proposes a new methodology for modular design The roadmap of this methodology is shown in the following figure:

and Primary Proeess

for Near Net Shape

Optimization Models and Sub-System Generation

1

Knowledge-Based Engineering and Deeision T rees

Simplification of Product Strueture

More Eeonomic Materials Processes and Maehines

Figure 1 Design for Modularity Life Cycle

-Chapter 1 sets the necessary background for product development by providing a discussion of sequential and parallel product development

xx Preface

processes Also, a generic product development process is shown in this

Chapter 2 provides a comprehensive explanation of the modular design concept, including types of modularity, the characteristics of modular systems, and the development of modular systems The concept of design structure matrix is presented in this chapter

In Chapter 3, a methodology is proposed for the development of complex

and the genetic algorithm models developed for the modularity problem

In Chapter 4, the methodology is further illustrated in a case study that shows how to design a four-gear speed reducer using design for modularity Chapter 5 illustrates the use of design for manufacture and assembly The concepts of design for assembly are presented, a methodology for implementing the concepts is presented, and the design of a fog lamp is presented to illustrate the methodology This chapter also discusses the concept of design for manufacture and template-based process planning A crankshaft model is used to illustrate the methodology

Chapter 6 is concemed with modularity in production systems through the design of cellular cells The concept of cellular manufacturing systems is first discussed, and a new methodology for modular cell design is then proposed

Sa 'Ed M Salhieh, Ph.D

AU K Kamrani, Ph.D

Chapter 1

Product Development Process: An Introduction

The product development proeess is a sequence of all the required activities that a company must perform to develop, manufacture, and seil a product These activities inc1ude marketing, research, engineering design, quality assurance, manufacturing, and a whole ehain of suppliers and vendors The process also eomprises all strategie planning, eapital investments, management deeisions, and tasks neeessary to create a new product

An important part of produet development is the engineering design process, whieh ean be defined as the proeess of devising a system,

eomponent, or proeess to meet desired needs [27] Engineering design eonsists of several sequential and/or parallel aetivities that begin with identifying a need and eonc1ude with a ready-to-manufacture product (prototype) The prototype is considered to be the first product completed in

and test procedures ealled for by the design drawings and specifications

DEVELOPMENT

Product development is evolving from a sequential process carried out primarily by engineers to an integrated process incorporating a cross-functional team Similar steps are followed in either case, but they are accomplished concurrently and with higher speed in the integrated process environment

Four logical groups of activities can be identified in product development [26]:

A K Kamrani et al., Product Design for Modularity

© Springer Science+Business Media New York 2002

2 Chapter J

In the first group, markets or potential markets are analyzed to generate customer needs, meaning the customer will eventually generate the requirements for the desired product features and functions Market information is usually compiled by marketing specialists, who translate it into a set of product features or product descriptions that are intended to satisfy a certain target customer base Also, this process includes analyzing other products that meet the target needs, offered by competitors, to find their points of both strength and weakness so that efforts can be made to overcome weaknesses and improve desired features Selling-price ranges are also estimated at this point by analyzing the pricing of similar products This, in addition to a value of desired profit margin, will set the criteria for the economic feasibility of the new product These data are translated into cost and quality specifications

The next step is to formulate the product into a concept based on the product feature set identified by marketing in the previous step, i.e., a first vision of how the product will look and perform is created Then the technical specifications of the product are developed Using this initial conceptual vision, the design process proceeds to design and test the product until a preliminary design is finished Then a prototype can be created and tested to make sure that the product is functioning as it should The prototype is considered the first finished product in the sense that it must be produced using all the manufacturing processes that the actual products will

go through Prototype testing may reveal a need for design modification; thus, the design will be refined and a new prototype produced This will continue until no more modifications are required The next step is to finalize the product documentation, and then the manufacturing process development may be initiated

Manufacturing processes must be created so that the product can be produced in the production facility Purchasing new equipment and training workers may be required if new technology is to be used Tools, fixtures, and the sequence of steps in the manufacturing processes must all be developed to allow rapid, high-quality, cost-effective production Also, it may be needed to rearrange the production facility to adapt to the new manufacturing processes

After completing the product design and the manufacturing processes development, the business of producing and shipping the product begins Raw materials can be purchased, and the production facility can go into operation During first production periods some problems may arise as a

Product Development Process: An Introduction 3 result of some technical production problems, which will lead to design modification to resolve these new problems and reach the expected production rate with the intended quality

DEVELOPMENT

The competitive nature of today's markets made product development the focal point of competition [87) The advantage goes to companies that are able to introduce new products effectively, and promptly Such companies steer their development effort towards meeting three main objectives: high quality, low price, and short time-to-market These objectives are often conflicting and must be compromised without significantly lowering the marketability ofthe product

The importance of effective and efficient product development can be further realized by understanding the impact of recent changes in markets and technologies These changes are [16,26,79]:

The number of companies capable of producing quality products in any given sector has dramatically increased in the last decade Companies worldwide are changing their practices to allow them to develop products globally That is, organizations need to develop global product development strategies that can capture the requirement of global customers, and produce products by utilizing global workforce

Customers nowadays are demanding products that can provide easy solutions to their own particular problems and needs One can say that customers have become too sophisticated and demanding This can be referred to the fact that customers are exposed to wide variety of products that are produced by companies across the globe

The growing depth and breadth of new technologies impacted both organizations and their customers Organizations have an enormous number

of technological options to use in product development; these options

4 Chapter 1

inc1ude marketing too1s, design too1s, production too1s, and distribution too1s As for customers, new techno10gies enab1ed them to reach new markets, 1eam about new products, and compare products quick1y

Changes in markets and techno10gies can never be controlled and organizations need to adapt to these changes rapid1y in order to compete Many organizations recognized this need and are working toward deve10ping

methodologies are discussed next

In the traditional development environment, each of the four logical groups occurs sequentially (Figure 1.1) Research precedes the development

of the new product concept, then concepts are developed by the research and development department through an iterative process until an agreed upon concept is found After that, a formal description of the concept is sent to the engineering department (design department), where a sequence of design work, review, and rework of design is made as the concept is being developed When the design is completely finalized it is "released" to manufacturing to define the manufacturing processes An important step that

is inc1uded in the manufacturing work is to determine which components will be made and which will be purchased When the manufacturing department finishes its study and a make/buy decision is reached, other departments such as those responsible for production planning and procuring materials can start to act Finally, materials must be ordered, necessary production equipment will be installed, workers will be trained, and the product can be produced and shipped

r!

L - - - - + l :

Figure 1.1 Sequential Product Development

The division of labor among distinct and separate departments enforces this sequential nature of the steps By the time a product is produced, each department will have performed its role in the long sequence of events

Product Development Process: An Introduction 5 leading to the production of this new product For the most part, each department has completed its work within its own functional area, consulting other departments only to obtain information needed or to review the results

of a task in the sequence The development process takes a relatively long period of time due to the nature of the sequential operations Also, technical problems can occur as a result of the lack of communication between functional borders Technical problems can cause rework, scrap, and customer complaints in addition to design changes if discovered later

DEVELOPMENT

The main disadvantage of the sequential method is the weakness of links between the functional departments that should be co operating to develop a new product [19] To overcome this weakness, it is necessary to change the steps of development into a more simultaneous and less sequential process,

as illustrated in Figure 1.2 [38]

Concurrent ProducllProcess Design Manufacturing

manufacturability cost assembly

process planning C§) ergonomics testing

analysis reliability

Figure 1.2 Simultaneous/lntegrated Product Development

The change of the development steps from sequential into simultaneous

can be facilitated by the use of the concurrent engineering (CE) philosophy

[18, 37, 86] Concurrent engineering can be defined as an integrated and systematic approach to the design of products and their related processes, including manufacturing, testing, and services Concurrent engineering improves quality, reduces costs, compresses cycle times, increases flexibility, and raises productivity as weil as efficiency

Concurrent engineering can be implemented in an integrated product development environment in which concept deve10pment proceeds simultaneously with research into possible technologies Engineers design components of the product that can be completed as information and technology become available Previous designs that fit the new application

6 Chapter 1

are reused or modified, reducing engineering time Simulation and prototyping occur simultaneously within engineering design activity As design work progresses, development beg ins on the manufacturing process All major functional areas participate in the design effort, and a cross-functional team must be formed

PROCESS

A generic product development process can be constructed starting with needs recognition and ending with the marketing of a finished product [75] The major phases are illustrated in Figure 1.3

Establishing Design Specijications

Once a need is realized, the next step is to interpret these needs into technical terms and specifications capable of describing the desired functional characteristics ofthe product under study

Conceptual Design

Several design alternatives are generated and evaluated for their functionality and cost effectiveness Solutions or concepts that meet the design specifications are generated in the form of ideas or alternatives A number of design alternatives are generated with no detailed analysis of any alternative At the end of this phase, the most acceptable concept is selected for further development and analysis

Product Development Process: An Introduction 7

Detail Design

In this phase, specifications are refined and trade-offs are made The selected concept is finalized according to the refined specification A final cost analysis is performed and a prototype model is produced as the final step in the development process

Production

Manufacturing processes capable of producing the parts according to the specified requirements are identified in this phase Manufacturing sequence and manufacturing costs are also assessed

Marketing

Product promotion and distribution to the target markets occur in this phase Packaging and storage requirements need to be addressed by the development team in order to assure the product's safe delivery

Following is a detailed discussion of each phase

Product development begins with identifying needs The design process can be identified based on an idea for a solution to an existing or identified need or from an idea for a product process for which it is thought a need can

be generated [79] The product idea needed must look promising given the current market situation, technology available, company needs, and economic outlook

the product development process Needs analysis should be aimed at collecting information about the requirements that must be fulfilled by the product and about the existing constraints and their importance Therefore, a requirement list can be formulated, which will form the basis for and guide the subsequent phases Finding and analyzing needs can be performed systematically as illustrated in Figure 1.4

J.4

8 Chapter I

Acquiring Information

Different types of information are needed to recognize a need or market opportunity This information includes all the necessary information about similar products (competitive products) obtained from published reference

information about registered designs, trademarks, patents, and copyrights This information will be analyzed to establish a competition analysis through

a benchmarking study

Information Analysis

At this stage all the information collected should be analyzed to gain greater insight about the proposed product or opportunity The result of this analysis will be the preparation of a "needs" list that represents a comprehensive statement structured to state just what should be designed to satisfy the user need Three main techniques for information analysis can be used [75]: parametric analysis, needs analysis, and matrix analysis

Parametrie analysis: Parametric analysis is a form of desk research that

perform a competition analysis by determining the product place in the market relative to the competition Also, parametric analysis is used to gain insight into the structure and interrelation between parameters inherent in the product under consideration by identifying the relationships between parameters for the particular product area under consideration This is done

by cross-plotting such parameters to see if a re1ationship exists between them

figure that parameter A decreases as parameter B increases Such plots are useful for identifying desirable parameters and comparing different products with respect to some desired parameters

Product Development Process: An Introduction 9

Figure 1.5 Parametrie Analysis Plot

Needs Analysis: The true needs of the customer-"The Voice Of the

Customer" (VOC)-is the main concern of the needs analysis Customer needs are established by conducting an extensive examination of the market data, product reports, structured interviews, and customer questionnaires

Matrix Analysis: A matrix is drawn up with all of the features of the

competitors' comparable products on the vertical axis and the model type on the horizontal axis The matrix is then completed to show which models incorporate which features; these are then summed simply and represented graphically on the right-hand side ofthe matrix

compared, which may indicate a special importance of this feature

1.6 Matrix Analysis

10 Chapter 1

Information Interpretation

At this step, the information is translated into a detailed list of customerlmarket requirements that must be satisfied by a product That is, the information gathered is interpreted into customer/market needs A list of product specifications is prepared that guides the product development process Although this list is not a rigid item and can be changed and refined when necessary, it is important to maintain the basic structure of the specifications in order not to violate customer needs

Needs Prioritizing

Customer/market needs specified earlier must be arranged in a hierarchy, beginning with the most general needs at the top level termed as primary needs The primary needs will be further characterized by a set of more detailed secondary and tertiary needs at the bottom levels The needs hierarchy may consist of severallevels; the main point here is to start with a general need and progress toward detailed needs

The needs hierarchy does not convey any importance of the needs, so needs' importance should be established based on either engineering assessment of the needs or a customer survey The establishment of need importance is critical in making a trade-off analysis and allocating design resources later on in the design process Needs' importance is usually expressed using an ordinal scale in which the most important needs are placed at the top of the scale and the least important at the bottom

Problem Statement

After identifying the needs and establishing their importance, a problem statement is prepared The problem statement is an abstraction of what the product is supposed to do to meet its needs This step is very important for the successive steps, since it will be treated as a "mission statement" for the design process

Establishing the design specifications is one of the most important and difficult elements in the overall design process The design specifications both drive and control the design throughout the process They are especially important during the early phases of the design effort because they serve as the principal guidelines for the project team at this point in the process The specifications are so critical to the ultimate design capability and its cost that they must be established early in the process They have to be established using sound judgments, with wide and in-depth coordination among key participants in the process and with test and analysis support when

Product Development Process: An Introduction 11

appropriate The design specifications need to be as specific to a system and component level as possible Although specifications are established to be permanent and inviolate, they should nevertheless be continually reviewed and revalidated during the design process, at least until the design is frozen,

to ensure that they continue to reflect the goals and objectives ofthe project

list of metries that reflects the degree to which the product meets the

the relationship of the new product to the competitive products Once the

target values are assigned to the selected metrics and the specijications are refined, the next stage (conceptual design) can start

The process of establishing design specifications can be further explained

by the following steps shown in Figure 1.7

Figure 1.7 Establishing Design Specifications

Prepare a List of Metries

Customer needs specified in the previous steps are translated into measurable characteristics that will reflect the degree to which the product satisfies the needs (metrics) The major assumption here is that the translation from customer needs to metrics is possible and each need can be represented by one (and only one) metric; thus, meeting the metrics will lead

to customer satisfaction Theoretically this assumption is valid, but there are needs that cannot be measured or that are difficult to represent by a single metric In this case, engineers can make the assumption that satisfying more than one metric will eventually lead to satisfying a certain need up to an acceptable degree

A useful tool that can be used when preparing the metrics list is the needs-metrics matrix [92], in which the rows ofthe matrix will correspond to the customer needs and the columns correspond to the metrics A generic needs-metrics matrix is illustrated in Figure 1.8, where a mark in a cell in the matrix means that the need and the metric associated with the cell are related The needs-metric matrix will represent the relationship between needs and metrics and assure that all of the customer needs are considered

Benchmarking is defined as the continual search for the implementation

of practices that could provide a competitive edge [46] Companies differ in the way they implement benchmarking, but it is usually adapted as a corporate strategy used to identify the industrial leaders, promote proven techniques and approaches, establish meaningful goals, perform business forecasting, and analyze the overall intemal process Benchmarking can be categorized into three major categories:

Internal Benehmarking: In this type of benchmarking similar activities

in various locations, departments, and units are evaluated to gain data accessibility

Competitive Benehmarking: This type of benchmarking is concerned with the identification and evaluation of direct competitors to obtain data relevant to the product under investigation and to find comparable processes

in order to gain a competitive edge

Generie Benehmarking: The objective here is to evaluate the organizations and their functions that are considered to be the industry standard in order to achieve procedure standardization

Value Assignment to Metries

In this step, the design team synthesizes aII the information acquired to

set actual va lues for the metries Two values are usually assigned to each metric: one is the ideal value, which can be defined as the optimal value that the design team hopes to accomplish, and the other is the minimum

Product Development Process: An Introduction 13

acceptable value, which can be considered as the lower limit that can satisfy the needs Usually, design will progress to achieve a metric value between the ideal and the lower limit; this is due to trade-offs performed throughout

primary objective

After the problem has been clarified and complete1y described, viable solutions are identified and the optimum approach is selected Problem solutions or "concepts" are defined as an approximate description of the product or technology that meets the stated needs The conceptual design

satisfy the needs, and it selects a concept that is most suited for matching the predefined design specifications Three major steps can be identified in the conceptual design phase:

The concept generation, or generation of ideas, begins with a defined problem statement that includes customer/market needs and design specifications and ends with several product concepts from which the design team will select the most suitable one A systematic procedure may be followed in generating concepts as shown in Figure 1.9

Figure 1.9 Concept Generation

Problem Formulation

Prepare an abstraction of the problem in order to broaden it out and

necessary at this point to break the problem down into several easier, understandable, and manageable sub-problems

Overall Function Analysis

Analyze the overall function by describing what the product or system is

describe functions in general terms as much as possible Furthermore, action statements in the form of verb-noun should be used in representing the functions, i.e., "to transform materials" or "to transmit information."

14 Chapter 1 Sub-Function Analysis

The overall function is now broken down into several sub-functions necessary for the product or the system to operate The sub-functions, when reassembled, should support and lead to the accomplishment of the overall function Sub-functions may be thought of as specifications or requirements imposed on the overall function

Function Diagram

A function diagram is a representation of the function structure, in which the function under study is represented by a block and the input and outputs are represented by arrows entering and leaving the block (function diagrams will be discussed in more detail in Chapter 3)

At this step, ideas and solutions for the sub-functions or the sub-problems are first generated and then combined together to form the overall function

or to solve the overall problem Ideas and solutions can be generated using different techniques The development team can use "brainstorming," in which a group of participants generates, in a set period of time, many ideas that can be used to solve the problem Brainstorming sessions usually aim at producing a large quantity of ideas irrespective of their quality Also, the development team can search published literature, patents, and catalogues for possible solutions Interviewing users can trigger some ideas for solutions A good practice in generating ideas is to try to reuse existing solutions or products in solving new problems

Concept selection is the process of evaluating and comparing alternative concepts with respect to the customerlmarket needs and design specifications, leading to the selection of the most suitable one or a set of concepts for further investigation andlor development Concept selection can

be performed according to the following guidelines in Figure 1.10

Product Development Process: An Introduction 15

Select Solution Principles

Suitable solution principles that can satisfy the needs are selected individually or in combination with other solutions Selected solutions should be able to perform the required function effectively and efficiently

Comhine Solution Principles into Complete Design Concepts

The selected principles in the previous step are arranged into a complete conceptual design that corresponds to the overall function, that is, concepts that correspond to sub-functions are arranged together to form a larger concept that can accomplish the overall function

Evaluate Concepts Technically

Concepts are now evaluated with respect to the degree to which they meet the design specifications; concepts that do not meet the specification are eliminated at this point

Evaluate Concepts Economically

Concepts are evaluated with respect to their cost, that is, concepts are investigated for their economic feasibility Non-feasible concepts with unjustified high costs are e1iminated

Select Final Concept

A final decision must be made among technically and economically feasible concepts by utilizing ascoring technique that can incorporate needs and customer satisfaction

This step of the design process bridges the gap between the conceptual design phase and the detailed design phase of the design effort The final concept is further defined during this step; the overall system configuration

is defined; and a schematic diagram, definition drawing, or other engineering documentation is developed to provide early praject configuration contra! System-level-and, to the extent possible, component-level design requirements should be established during this phase of the design process in

a manner that corresponds to the design specifications previously defined

Detail design (Figure 1.11) is that part of the design in which, starting from a concept of a technical product, the design is developed in accordance with technical and economic criteria At this phase, the design concept is

16 Chapter 1

resolved into its component parts, components are evaluated to validate previously established requirements, and the effect of the component requirements on the overall system requirements is evaluated Also, all the arrangement, forms, dimensions, and surface properties of all the individual parts are finally laid down; the materials specified; production possibilities assessed; costs estimated; and all the drawings and other production documents produced The intent of the detail design phase of the project is to develop a system of drawings and specifications that completely describes a proven and tested design so that it can be manufactured

Component

Finaj Design Cost Estimation

Figure 1.11 Detail Design

Prototyping

The overall product concept generated in the previous step is now designed by designing its components Components are designed to meet the product specifications identified earlier The result of the component design

the overall product specifications The component specifications, in general, will contain a list of all the necessary information required to procure or manufacture the component such as operating parameters, component dimensions, material, etc Component final design is represented in several documents such as detail drawings, assembly drawings, and bills of materials

The cost of producing or developing the selected conceptlproduct is estimated lustification of the trade-offs considered must also be included in this study

A functional prototype model of the product is made at this point Further investigation conceming the actual functionality and appropriateness of the product developed can be made on this model as a final step before starting production and introducing it to the market

Product Development Process: An Introduction 17

Production process planning aims at constructing a production plan that utilizes the available machinery to produce products efficiently and effectively Production planning begins by analyzing the detail design documentation, which inc1udes information about the product's geometrical features, dimensions, tolerances, materials, and surface finish This information is treated as targets that must be met The process proceeds to identify the appropriate machinery capable of achieving the design targets The sequence of operations is also identified

Design for manufacture and assembly is an important concept used in the production phase to gain greater insight about how the product design interacts with the manufacturing system and uses this knowledge to design better-quality products that can be produced for lower cost and in less time [8, 37, 79] Design for manufacture and assembly will identify the product design alternatives that will facilitate the optimization of the manufacturing system as a whole

Following are some general guidelines that can be used in design for manufacture and assembly:

automation can be considered Product design should be made with automated assembly in mind

eliminate manufacturing tasks that require special skills

necessary to design parts that perform several functions Reducing the number of parts will decrease the production cost significantly

modular product

• Use standardized parts

more than one function

Although design engineers are not involved directly in product promotion and distribution, information about problems that occur during the marketing and distribution of products should be integrated into the product design Design engineers should design packaging to protect products from damage during transport and storage The design engineer must specify any special shipping and storage requirements

18 Chapter 1

Design engineers can also be involved in the promotional activity by interpreting customers' questions and criticism about the products and relating them to design specifications This will enable the design engineer

to modify the product deign and improve it to correspond to customer needs

Product development begins with identifying a market opportunity based

on customer needs A market opportunity exists, in product development terrninology, when there is a need that can be satisfied by a product of engineering effort In this approach, the market or the customer perforrns as the trigger that initiates (pulls) the development of new products in the sense that the voice of the customer is emphasized, and all the development effort

is focused on producing a product that is acceptable to the prospective users Customers or markets provide the requirements that the product must meet These requirements are analyzed by the design team and incorporated into the design process Design specifications and concepts capable of meeting these specifications are also developed according to customer/market requirements

Organizations begin with a pre-established unique technology and try to find a market opportunity where this technology can be appropriate In developing successful technology-push products, organizations use basic materials or basic process technologies This can be referred to the fact that basic materials and basic processes can be deployed in many different applications, which makes it possible to satisfy different market needs The methodology described in the previous section can be used with some modification for technology-push products The modification will add

an activity at the beginning of the needs recognition phase during which available or proposed technologies are identified Then the market research activity will have an objective of locating candidate marketing opportunities where the technology under investigation can be applied

Product Development Process: An Introduction 19

These products are built around a pre-exIstmg technological system (technological platform) Organizations invest huge capital in developing technological platforms Therefore, it is weil justified that every possible attempt should be made to incorporate these platforms into as many different products as possible

Platform products resemble technology-push products in that both start with an assumption that a certain technology must be incorporated into the products Platform products differ from technology-push products in that the platform technology has already proved its ability to meet market needs, and the organization can assume that the technology will be useful in related markets

The production process is considered as one of the main constraints placed on the product design Developing process-based products is usually done for mass production or continuous production

These products are developed in direct response to customer needs Customized products are variations of an existing standard configuration of products To develop customized products, organizations need to set values for design variables such as physical dimensions These design variables will

be changed to meet customer requirements

Products are designed as building blocks that can be grouped together to form a variety of products This approach will promote standardization and the re-use of existing modules to develop new products Modular design methodology will be further explained in the next chapter

7 CASE STUDIES

Single-use cameras are used by a specific customer base, those who want

an inexpensive camera for certain occasions to take pictures

Statement of the purpose

Description ofthe market

Description ofthe competition

Product Development Process: An lntroduction 21 Sampie of competitive product information:

Frame Counter Subtractive

Sampie of customer interview:

Question: Have you ever bought a single-use camera?

Why did you buy it?

I needed an inexpensive camera I can take with me when I go camping

Where did you use the camera the most? WeIl, I used i t outdoors, both day and night time It's a good thing i t had a flash

Market Information Analysis

Market information collected is tabulated to facilitate the analysis as following:

22 Chapter 1

Customer Information Analysis

Customer Interviews are analyzed to determine the customer needs Figure 1.13 shows the customer statements and the appropriate need interpretation for each statement

I need a camera to take anywhere The camera has a compact size

Sometimes I take picture indoors I

I don't like the edges ofthe camera The camera has rounded edges

It would be nice if the camera would fit in

I need the camera to be light and thin The camera is light and thin

I need to be able to shoot almost anything

The camera has a fixed focus without adjusting the focus

I don't like waiting too long for the flash

The flash recharges quickly

to recharge

I don't like to loadlunload films The camera has a preloaded film

It would be ni ce if the camera had a strap The camera has a hand strap

I expect the camera to have a low cost The camera is low cost

Figure 1.13 Single-use Camera Needs Interpretation

Matrix Analysis - Needs Analysis

The matrix analysis is used to analyze the features available in competitors' products The analysis results are shown in the following figure

Product Development Process: An Introduction 23