Koren Y. The Global Manufacturing Revolution: Product-Process-Business Integration and Reconfigurable Systems

Подождите немного. Документ загружается.

3. The selection of product variants is the ﬁnal step in the design of a product

family. This selection of product variants is critical for determining the

proﬁtability of the product family. By increasing the number of product

variants, a manufacturer may increase the product family’s sales. However,

an increase in the number of produc t variants also leads to increased production

costs. Therefore, a manufacturer must employ strategies to determine which

combination of product variants would lead to optimal product family proﬁts.

Maximizing the number of base components that are shared across the same

family, but still providing unique functions to each variant, impacts the ability of

companies to offer product variety at low cost. S. Kota et al. conducted researc h that

studied the product family design of Walkman



-type cassette players.

A relevant

example of this study is depicted in Figure 3.10. In Sony EX122 , a single ﬂexible

guide is present at the lower left-hand portion of the component, whereas two such

guides are present in FX321 . This minor difference, which can be added easily in the

assembly process, adds a new function—auto-reverse—in the FX321, whereas the

EX122 has just auto-stop.

Example:

A manufacturer wishes to produce a family of disposable cameras, and to

capture the greatest possible market share. Every variant of the product family (the

product’s platform) must have ﬁve base component s: (1) an interior body, (2) a six-

part shutter mechanism, (3) inner lens, (4) outer lens, and (5) camshaft.

Figure 3.9 Product family architecture and two possible product variants of an ofﬁce

chair.

Dr. April Bryan (the author’s former Ph. D. student) wrote this example and its solution.

PRODUCT MODULARITY 91

There are six differentiating components:

1. Three different versions of front and back covers, which are offered as a

combination.

2. Two different ﬁlm holder/advance mechanisms (six parts in each).

3. Three different lens holders.

4. Two different viewﬁnders.

5. A washer.

6. A circuit board and battery for the ﬂash.

Each camera must have either a washer, or a circuit board and battery. Cameras

with the washer also have the front and back exter ior covers an d outer ﬁlm

advance. These latter components a re not in the cameras with the circuit board

and battery.

(a) What is the maximum possible number of product variants that the manu-

facturer can offer in the disposable camera product family?

(b) The manufacturer selects three variants of disposable cameras for the product

family. One of thesevariants will be used in water. The camera that will be used

in water has the washer, the outer ﬁlm advance, and the fron t and back exterior

covers. The other two variants do not have these components. The water

camera also has a different version of the viewﬁnder than the other two

cameras. The camera that will be used in water and one other camera have the

same ﬁlm holder/advance mechanism. Each camera has a unique lens holder

and front and back cover. Calculate the CPI.

Solution

Let us start by arranging the various alternatives in a tabular format.

Figure 3.10 Single and double ﬂexible guides employed to serve different functions in

Sony EX122 (top) and FX321 (bottom) models.

CUSTOMIZED, PERSONALIZED AND RECONFIGURABLE PRODUCTS

Module # Base Components Number of Alternatives

1 Interior body 1

2 Shutter mechanism 1

3 Inner lens 1

4 Outer lens 1

5 Camshaft 1

Differentiating Components

1 Front cover and back cover d

1 ¼

2 Film holder/advance mechanisms d

2 ¼

3 Lens holder d

3 ¼

4 Viewﬁnder d

4 ¼

5 Circuit board with battery d

¼ 2

6 Washer

Front and back exterior cover

Outer ﬁlm advance d

6 ¼

a. Using v

¼ (d

 d

)/d

¼ 72. There are 72 possible variants.

Sub-assembly/

Components

Number of

Alternatives

Number of

parts/

Components

Total Number

of Unique

Components

Front cover 3 1 3

Back cover 3 1 3

Film holder/advance

Mechanism

26 12

Lens holder 3 1 3

Viewﬁnder 2 1 2

Circuit board 1 1 1

Battery 1 1 1

Front exterior cover 1 1 1

Back exterior cover 1 1 1

Washer 1 1 1

Outer ﬁlm advance 1 1 1

Interior body 1 1 1

Shutter mechanism 1 6 6

Inner lens 1 1 1

Outer lens 1 1 1

Camshaft 1 1 1

Summarizing the total of the right column yields the number of unique

components—39.

PRODUCT MODULARITY 93

3.4.3.1 Camera Variant 1 Components: Base components, washer, outer ﬁlm

advance, front exterior cover, back exterior cover, viewﬁnder (instance 1), ﬁlm holder/

advance mechanism (instance 1), front cover (instance 1), back cover (instance 1),

lens holder (instance 1).

Number of Components ðp

Þ¼24

3.4.3.2 Camera Variant 2 Components: Base components, circuit board, battery,

viewﬁnder (instance 2), ﬁlm holde r/advance mechanism (instance 1), front cover

(instance 2), back cover (instance 2), lens holder (instance 2).

Number of Components ðp

Þ¼22

3.4.3.3 Camera Variant 3 Components: Base components, circuit board, battery,

viewﬁnder (instance 2), ﬁlm holde r/advance mechanism (instance 2), front cover

(instance 3), back cover (instance 3), lens holder (instance 3).

Number of Components ðp

Þ¼22:

¼ 24 þ 22 þ 22 ¼ 68 max p

¼ 24 Number of unique components: u ¼ 39:

The commonality index : C:I: ¼ 1

umaxðp

j¼1

maxðp

¼ 1

3924

6824

¼ 0: 66

where u is the number of unique components, which is 39 in this example; p

is the

number of components in product variant j; v

is the ﬁnal number of product variants

offered, which is 3 in this case; note that 24 þ 22 þ 22 ¼ 68.

3.4.4 Beneﬁts and Drawbacks of Product Modularity

Product modularity requires developing product platform architect ure on which the

modular products can be built. A modular architecture may also be built on a bus

(similar to computer interfaces) to which different components are attached, depend-

ing on the desired functionality of the product. Modularity requires interfaces, which

make the product more expensive (especially the mechanical interfaces). Additional

cost is associated with testing the product integration at assembly.

By contrast,

integral design is less expensive, since there is no need for interfaces, but an integral

design reduces the possible variety of products in the family.

On the other hand, product modularity offers value by providing a broader range

of products. Value can be gained, for example, by designing products that can be

customized to ﬁt various population sectors or different regional cultures, and still

be manufactured at low cost. Modularity offers the option of building reconﬁgurable

products, which may add value to an enterprise. Still, modularity may be more

expensive, and, in some cases, even delay the product’s time to market.

94 CUSTOMIZED, PERSONALIZED AND RECONFIGURABLE PRODUCTS

We summarize below several beneﬁts and drawbacks of product modular

architecture.

3.4.4.1 Beneﬁts of Modularity

1. Design for globalization: Different market segments around the globe have

different requirements, and modularity enables companies to offer products

tailored to the target market. This is especially important in globalization where

target markets are in different countries. Modularity enables providing products

that ﬁt a region or a particular culture at short leadtime and reasonable price.

2. Design for variety: Even when considering the same particular market,

offering product variety is adding value. Different consumers have different

tastes and modularity allows tailoring product options to customer’s needs and

price range. Modularity supports the concepts of mass customization and

personalization.

3. Reconﬁgurable products: Product modularity enables offering reconﬁgur-

able products. Modularity also allows a reconﬁgurable product to be designed

for upgrading .

4. Component economies of scale: When applying modularity, the same basic

components are used across different products of the family. When a component

is used in many product lines, its production volume is higher than if a

component is designed just for a particular product.

5. Differential consumption: Not all components have the same lifetime.

Modular design enables upgrading some of the com ponents, without having

to change out the whole product.

6. Ease of product diagnosis, maintenance, service, and repair: Modularity

simpliﬁes problem identiﬁcation and repair.

7. Decoupling the design tasks: The design of the modules can be done

simultaneously, thereby reducing the time to market.

8. Response to markets: A modular structure allows a ﬁrm to respond quickly to

changes in product design and to rapidly integrate new technology.

9. Rapid product changes: Product changes can be made without affecting the

entire design. A functional change can be achieved with minimal physical

change to the product.

3.4.4.2 Drawbacks of Modularity

1. Ease of reverse engineering: By making different components, it is more

vulnerable to copy a modular product.

2. Increased product costs: The interfaces add intrinsic costs in material and

detail design time, as well as the testing for integration of modules.

3. Excessive product similarity: Modularity may make products in the family

look too similar.

PRODUCT MODULARITY 95

3.5 RECONFIGURABLE PRODUCTS

Reconﬁgurable products can alter their shape during their lifetime to adapt to new

applications, additional emerging needs, and changing customer preferences. Awell-

known biblical example of product reconﬁguration is: “They will beat their swords

into ploughshares and their spears into pruning hooks.” However, the test for a truly

reconﬁgurable product is whether one can also change that pruning hook back into

a spear at will, and how easily it is accomplished.

Product modularity is a sufﬁcient, but not necessary condition to create reconﬁ-

gurable products. Reconﬁgurable products must be convertible from one shape to

another (see example in Figure 3.11), and/or scalable from one size to another (bigger

or smaller). For example, reconﬁgurable children bicycles could be adapted (i.e.,

scaled) to the child’s height. A reconﬁgurable chair may be placed upside down and

modiﬁed to become a stepladder. Well-designed reconﬁgurable products are easily

modiﬁable by the end-user, the customer. Such products can be reconﬁgured over and

over as the end-user sees ﬁt.

Another familiar example is the rear automobile seat. For years, automob ile seats

have been made that could be repositioned to allow easier access from one part of the

passenger compartment to another. Then, an innovation was introduced, particularly

in hatchback style cars; where a rear seat back could be folded down to provide a ﬂat

surface to increase cargo space. And when the user again needed more seating, the seat

back could be returned with minimal effort. The earlier seat back function was merely

repositionable, since the seat was still a seat. The innovation changed the seat into

Figure 3.11 A reconﬁgurable chair is modiﬁed to become a stepladder.

CUSTOMIZED, PERSONALIZED AND RECONFIGURABLE PRODUCTS

something else entirely. The car seat has become reconﬁgurable into two modes: an

extended deck for storing cargo and an equally usable rear passenger seat.

What if a car seat could be completely removed to make space for customer-

speciﬁed accessories, such as a mini-desk, small fridge, dog basket, etc.? If such an

accessory is not attac hed correctly, it will become dangerous during a collision or even

a severe braking event, and could lead to a serious injury. The legal implications in

cases like that could be signiﬁcant for a product manufacturer. Nevertheless, similar

debates about legal consequences happen ed before air bags became a standard

accessory in vehicles. Similarly, we believe that vehicle interior reconﬁgurability

will become a reality in the near future, despite possible legal consequences, because

the market will demand it.

Since the turn of the last century, a broad range of reconﬁgurable products have

appeared on the market, from furniture to toys that can be reconﬁgured from robots to

racecars and back again. One more recent example of a reconﬁgurable product—the

reconﬁgurable tricycles—is shown in Figure 3.12.

The reconﬁgurable tricycles product has three possible conﬁgurations. First, the

base is locked under the unit for rocking fun by very young toddlers, as (shown at

left)—this is Position 1. As the child grows, the tricycle can be reconﬁgured to

Position 2—the rocking base is converted to a long push handle so an adult can stroll

behind while the child learns to pedal. When the kids are ready to ride on their own,

the handle is removed completely and the seat is adjusted to their height, so they can

reach the foot peddles (Position 3). This is a reconﬁgurable product that demonstrates

three core characteristics:

Modular

Integratable

Convertible

How about having these characteristics in automobiles, so that customers are able

to change their vehicle according to their needs? The invention of the automobile

signiﬁcantly changed our lives in the ﬁrst part of the twentieth century. But how

Figure 3.12 Reconﬁgurable tricycles (http://www.ﬁsherprice.com/).

This photo was taken from a sales magazine in 2001.

RECONFIGURABLE PRODUCTS 97

little the sedan style has changed over the past 50 years. Why are not there

reconﬁgurable add-on trunks offered for cars? A trunk that is shorter and allows for

easier parking in a crowded city, where parallel parking is a necessity, can be made

longer for a luggage/storage space when going on vacation or shopping (Figure 3.13).

Why cannot we see more reco nﬁguration in back seats? How about seats that can

be arranged for comfortable conversation? And how about the front passenger seat?

Can it be built with a tray (as in airplanes)? How about reconﬁguring the passenger

seat into a convenient bed for long trips, or made so that it can invert into a rear-facing

seat to join in the conversation with passengers sitting in the back of the car?

3.6 DESIGN OF CUSTOMIZED AND RECONFIGURABLE PRODUCTS

Customized and reconﬁgurable products have basic features in common.

1. Both are deﬁned around product families

2. Both obey a set of design principles that ﬁt this product category

3. Both shar e a set of core characteristics

3.6.1 Product Families

Fundamental to the mass customization paradigm is the concept of part families and

product families. From a manufacturing point of view, any parts that serve a similar

function within a comparable range of sizes and mad e from the same sort of materials

using the same methods belong to a part family. Conceptually, all customized

ﬁnished products with similar form and function belong to a product family. All

products from the same family possess the same basic functionality, and play

essentially the same product role. A basic ofﬁce chair, for example, must have a

seat and legs, although some members of the product family may have armrests and

wheels, as depicted in Figure 3.14.

The concept of a part or product family is essential for mass customization and

personalization. The rationale is double fold. First, it is less expensive to design

variety into a product family by using the principles of modularity, and second, if the

production is done on a manufacturing system that is designed to produc e a part

family, or a product family, the production cost is much less expensive and similar to

that of mass production.

Figure 3.13 Reconﬁgurable automobile cargo (artist Rod Hill).

CUSTOMIZED, PERSONALIZED AND RECONFIGURABLE PRODUCTS

The reconﬁgurable manufacturing systems that will be discussed later in the book

are designed to produce product families or part families, and thereby become

important enablers to reduce manufacturing costs in mass customization and

personalization.

Similar to the base and differentiating components of modularization, when

designing and identifying members of a part/product family one should distinguish

between two basic groups of features:

Core family features: deﬁne the functions that are required in all products within a

part/product family, and thus deﬁne the family.

Augmenting features: help to satisfy different market needs and are not essential

for deﬁning membership in the part/product family.

3.6.2 Design Principles for Customized Products

Both customized and reconﬁgurable products must obey a set of basic design

principles:

Core functionality must remain unchanged across all products within a

family: The core functionality and features deﬁne the product family. If that

core functionality is missing, it is a different product. Note that a Walkman that

does not have resistance to vibration cannot serve its main mission.

Minimize non-value-added variations across variants within a product

family: Non-value-added variation does not actually extend the range of

products offered. It amounts to a marketing trick to attract customers. Product

variety should beneﬁt the customer, and adding unimportant variety that

confuses the customer can reduce sales.

Key design characteristics must be embedded in the product architecture:

Basic design features that enable cost-effective production of customized,

personalized, and reconﬁgurable products must appear in all members of the

product family.

Figure 3.14 A product family of ofﬁce chairs.

DESIGN OF CUSTOMIZED AND RECONFIGURABLE PRODUCTS 99

3.6.3 Core Characteristics of Customized and Reconﬁgurable Products

There is a set of six product characteristics that make a product suitable for mass

customization, personalization, and reconﬁguration.

Modularity Product modularity enables the change of product shape to ﬁt

various customers and utilizations

Integrability Integrability refers to deﬁned module interfaces (mechanical,

electrical, and information) for ease of product reconﬁg-

uration and customization

Customization Customization provides customers with just the product

functions they need, and not features that they will not use

Convertibility Convertibility enables products to be changed to fulﬁll

various utilizations of the same product

Scalability Scalability allows a product to be scaled up or down to ﬁt to

the user’s body or applications

Diagnosibility Diagnosibility means that a product is designed with em-

bedded diagnostic functions, for easy service and

maintenance

The table below and Figure 3.9 show the key characteristics that should be

embedded in customized and reconﬁgurable products.

Product Type Modularity Integrability Customization Convertibility Scalability Diagnosability

Customized vv v v

Reconﬁgurable vv v v

When implementing the characteristics, the designer should distinguish between

necessary and sufﬁcient conditions. Modularity is a necessary condition to achieve

variety within families of customized and personalized products. Product modularity

is not, however, a necessary condition for creating reconﬁgurable products, although

it is sufﬁcient to achieve product reconﬁguration (e.g., lego).

With the characteristics of modularity, integrability, convertibility, and scalability,

reconﬁgurable products can be designed for easy modiﬁcation as the customer’s needs

change over time. The characteristics of convertibility and scalability (with a child’s

age and development) are demonstrated in the reconﬁgurable tricycle depicted in

Figure 3.15.

Customized products can be designed with cost-effective variety by embedding

the characteristics of modularity, integrability, and customization. Diagnosibility is

needed in more complex products, such as cars.

The example of the customized digital camera in Chapter 2 describes the dilemma

of implementing customization: “You interview a thousand people, and each one says

100 CUSTOMIZED, PERSONALIZED AND RECONFIGURABLE PRODUCTS