INSE 6411 Product Design Theory and Methodology

Product Architecture and Design for XLecture 9

Andrea Schiffauerova, PhD.

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Product architecture• Product architecture is the assignment of the functional

elements of a product to the physical building blocks of the product.▫The functional elements are the individual operations and

transformations (expressed by VERBS)▫The physical elements of a product are the parts,

components, and subassemblies The physical elements of a product are typically organized into

several major physical building blocks, called chunks. The purpose of the product architecture is to define the basic

chunks in terms of what they do and what their interfaces are

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Modular product architecture• Each chunk fully embodies one or

more product functions.• Interactions between chunks are:▫well defined▫ (typically) fundamental to product‘

primary functions.• Advantages:▫ simplicity▫ reusability for a product family or

platform. ▫easier design changes

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Integral product architecture• Typical functions involve more than

one chunk• Typical chunks implement more than

one function• Interactions between chunks are ill-

defined and may be incidental to product's primary functions.

• Advantages:▫ increased performance▫ reduced costs for any specific product

model.• However:▫ it may require extensive redesign of

the product if a design change is made

Modular architectureExample: Trailer

box

hitch

fairing

bed

springs

wheels

protect cargofrom weather

connect to vehicle

minimizeair drag

supportcargo loads

suspendtrailer structure

transfer loadsto road

Physical chunks: Product functions:

Integral architectureExample: Trailer

upper half

lower half

nose piece

cargo hangingstraps

spring slotcovers

wheels

protect cargofrom weather

connect to vehicle

minimizeair drag

supportcargo loads

suspendtrailer structure

transfer loadsto road

Physical chunks: Product functions:

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Product architecture•Modular or integral architecture?

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Modularity - types• Modularity is a relative property ▫ Products are rarely strictly modular or integral.

• Slot-modular architecture▫ Each chunk-to-chunk interface is different from the

others.▫ Chunks cannot be swapped around.▫ Ex.: automobile radio, speedometer

• Bus-modular architecture▫ Uses a common bus, or similar concept.▫ Uses standard chunk-to-bus interfaces.▫ Ex.: expansion card for PC

• Sectional-modular architecture▫ No common bus or other single element interfacing

with all other chunks.▫ Uses standard chunk-to-chunk interfaces.▫ Ex.: sectional sofa, office partitions, piping systems

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Product architecture selection•Architecture decisions relate to product planning and

concept development decisions:▫Product change▫Product variety▫Standardization▫Performance▫Manufacturing cost▫Project management▫System engineering

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Establishing the architecture1. Create a schematic illustrating product architecture2. Cluster elements3. Identify fundamental and incidental interactions

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1. Create a schematicDeskJet Printer Schematic

Flow of forces or energy

Flow of material

Flow of signals or data

StoreOutput

StoreBlankPaper

EnclosePrinter

ProvideStructuralSupport

PrintCartridge

PositionCartridgeIn X-Axis

PositionPaper

In Y-Axis

SupplyDC

Power“Pick”Paper

ControlPrinter

CommandPrinter

Connectto

Host

CommunicatewithHost

DisplayStatus

AcceptUser

Inputs

Functionalor PhysicalElements

2. Cluster elements into chunks

StoreOutput

StoreBlankPaper

EnclosePrinter

ProvideStructuralSupport

PrintCartridge

PositionCartridgeIn X-Axis

PositionPaper

In Y-Axis

SupplyDC

Power“Pick”Paper

ControlPrinter

CommandPrinter

Connectto

Host

CommunicatewithHost

DisplayStatus

AcceptUser

Inputs

Paper Tray PrintMechanism

Logic Board

Chassis

Enclosure

User Interface Board

Power Cordand “Brick”

Functionalor PhysicalElements

Chunks

DeskJet Printer chunks

Host DriverSoftware

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2. Cluster elements into chunks•Key considerations when clustering elements (of

schematic) into chunks include:▫Geometric integration and precision

Ex.: H-P clustering for ink-jet printer calls for cartridge positioning on x-axis and paper positioning on y-axis

▫Function sharing Ex.: Status display and user controls for H-P printer

▫Vendor (= Supplier) capabilities▫Similarity of design or production technology▫Location of change▫Accommodating variety▫Enabling standardization

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3. Incidental interactions• Identification of interactions between chunks:•Fundamental interactions▫Planned, well understood interactions▫Ex.: H-P printer: Sheets of paper flow from the paper

tray to print mechanism.• Incidental interactions▫Arise due to the implementation of elements▫Ex.: H-P printer: Vibration induced by the actuators in

paper tray may interfere with precision positioning of print cartridge (x-axis)

3. Incidental interactions Interaction graph

Enclosure

Paper Tray

Chassis

PrintMechanism

User InterfaceBoard

LogicBoard

Power Cordand “Brick”

Host DriverSoftware

Styling

Vibration

Thermal Distortion

Thermal Distortion

RF InterferenceRF

Shielding

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Delayed differentiation•Product architecture can be a key determinant

of the performance of the supply chain•Delayed differentiation is postponing the

differentiation of a product until late in the supply chain

•May offer substantial reductions in the costs of operating supply chain, primarily through the reductions in inventory requirements.

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•Figure 9.10

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Delayed differentiation

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Design for X•Design for X summarizes a wide collection of specific

design guidelines. •X = quality criteria▫Design for Manufacturing▫Design for Assembly▫Design for Reliability▫Design for Testing▫Design for Maintenance▫Design to Cost▫Design for Value

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Design for Manufacturing•Widely used• Poorly defined (the definition may include various practices)▫DFM is establishing the shape of components for efficient,

high-quality manufacturing• Key concerns:▫Specifying the best manufacturing process for each

component:▫Ensuring that the component form supports the

manufacturing process selected• For each manufacturing process there are design guidelines that

result in consistent components and little waste

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Design for Assembly•DFA is the best practice used to measure the ease

with which the product can be assembled▫DFM focuses on making the components and DFA is

concerned with putting them together•DFA measures a product in terms of the efficiency of

its overall assembly and the ease with which components can be retrieved, handled and mated.▫Retrieval of the components from storage▫Handling the components to orient them▫Mating the components (bringing them together)

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Design for Assembly

Old seat frame

Redesigned seat frame

9 components20 operations

30 min to assemble

4 components8 operations

8 min to assemble

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Design for Assembly•Meaningful only for mass produced products! ▫Expensive tooling is justified only if spread over a large

manufacturing volume▫In low volume products there is a little payback for

changing a design for easier assembly (the cost of assembly is only 1-5% of the total manufacturing cost)

•13 DFA guidelines to make products as easy to assemble as possible

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Design for Assembly•Guideline 1: Minimize overall component count▫Examine each pair of adjacent components and determine

whether they have to be separate (to operate mechanically, different materials, etc.)

Common nail clipper

Nail clipper with one interface for each function A one-piece nail clipper

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Design for Assembly• Guideline 2: Make minimum use of separate fasteners▫Each fastener is one more component to handle▫Every fastener adds costs▫Fasteners are stress concentrators

• Guideline 3: Design the product with a base component for locating other components▫A single base on which all other

components are assembled

A single base for locating other components

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Design for Assembly•Guideline 4: Do not require the base to be

repositioned during assembly▫Repositioning may be time consuming and costly

(especially on larger products)

•Guideline 5: Make the assembly sequence efficient▫An efficient assembly sequence:

Involves only few steps Avoids risk of damaging components Avoids awkward or unstable positions Avoids creating many disconnected subassemblies

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Design for Assembly•Guideline 6: Avoid component

characteristics that complicate retrieval

▫Tangling

Modifications to avoid tangling

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Design for Assembly

▫Nesting

Modifications to avoid nesting

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Design for Assembly• Guideline 7: Design components for a specific type of retrieval,

handling and mating▫Manual assembly (less than 250 000 products annually)▫ Robot assembly (up to 2 million annually)▫ Special-purpose machines (more than 2 millions annually)

• Guideline 8: Design all components for end-to-end symmetry▫End-to-end symmetry is a

symmetry about an axis perpendicular to the axis of insertion – a component can be inserted in the assembly either end first

Modification of parts for end-to-end symmetry

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Adding a hole and rounding the end

• Guideline 9: Design all components for symmetry about their axes of insertion▫Strive for axis-of-insertion symmetry (rotational symmetry)

Modification of features for symmetry about the axis of insertion:

Adding a functionally useless notch

Design for Assembly

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Modification of a part for symmetry

Design for Assembly

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Design for Assembly•Guideline 10: Design

components that are not symmetric about their axes of insertion to be CLEARLY asymmetric▫Make components that

can be inserted only in the way intended (easy orientation)

Modification of parts to force asymmetry

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Design for Assembly• Guideline 11: Design components to mate through straight-

line assembly▫To minimize the motions of assembly▫No reorientation of the base▫All the motions are straight down

One-direction assembly

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Design for Assembly

• Guideline 12: Make use of chamfers, leads and compliance to facilitate insertion and alignment▫Each component should

guide itself into place

Use of chamfers (rounded corners) to ease assembly

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Design for Assembly

Use of leads to ease assembly

Use of compliance to ease assembly

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Design for Assembly•Guideline 13: Maximize component accessibility▫Assembly can be difficult if components have no clearance

for grasping▫Assembly efficiency is low if a component must be inserted

in an awkward spot

Modification for tool clearance to ease assembly

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Design for Reliability• Reliability is a measure of how the quality of a product is

maintained over time• Failure is an unsatisfactory performance•Methods:▫Failure Mode and Effects Analysis (FMEA)

Helps in identifying the failures, their causes and the corrective actions

▫Fault Tree Analysis (FTA) Helps in finding failure modes Graphically shows all the potential faults and their relationships

▫Mean Time Between Failures (MTBF) Average time elapsed between failures

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Design for Testing•Testability is the ease with which the performance of

critical functions is measured

Design for Maintenance

•Maintainability or serviceability or reparability describe the ease of diagnosing and repairing the product

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Design for Environment•Green design or environmentally conscious design or

life-cycle design or design for recyclability•After a product’s useful life, the components are

disposed (1970s and 1980s), reused or recycled (more and more nowadays)

•Why?▫Economics▫Customer expectation▫Government regulations

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Design to Cost•Design to Cost is a process that constrains design

options to a fixed cost limit. ▫The cost limit is usually what the buyer can pay or

what the marketplace demands. ▫An affordable product is obtained by treating target

cost as an independent design parameter that needs to be achieved during the development.

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Design for Value•Value engineering is a customer-oriented approach to the

entire design process▫The focus changes from the cost of a component to its

value to the customer

▫Value is function provided per dollar of cost•Compare worth to cost to identify features that have low

and high relative values

featureoftcustomerthetofeatureofworthValue __cos_____

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Next lecture•Project management•Product development economics• Intellectual property rights•Robust design