INSE 6411 Product Design Theory and Methodology Product Architecture and Design for X Lecture 9 Andrea Schiffauerova, PhD.

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

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

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 architecture Example: Trailer Physical chunks: Product functions: box protect cargo from weather hitch connect to vehicle fairing minimize air drag bed support cargo loads springs suspend trailer structure wheels transfer loads to road

Integral architecture Example: Trailer Physical chunks: Product functions: upper half protect cargo from weather lower half connect to vehicle nose piece minimize air drag cargo hanging straps support cargo loads spring slot covers suspend trailer structure wheels transfer loads to road

Product architecture Modular or integral architecture?

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

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

Establishing the architecture Create a schematic illustrating product architecture Cluster elements Identify fundamental and incidental interactions

1. Create a schematic DeskJet Printer Schematic Enclose Printer Print Cartridge Provide Structural Support Accept User Inputs Display Status Position Cartridge In X-Axis Store Output Position Paper In Y-Axis Control Printer Supply DC Power Store Blank Paper “Pick” Paper Communicate with Host Command Printer Functional or Physical Elements Flow of forces or energy Flow of material Flow of signals or data Connect to Host

2. Cluster elements into chunks Enclosure DeskJet Printer chunks Enclose Printer Print Cartridge User Interface Board Provide Structural Support Accept User Inputs Display Status Position Cartridge In X-Axis Chassis Store Output Position Paper In Y-Axis Control Printer Power Cord and “Brick” Supply DC Power Store Blank Paper “Pick” Paper Print Mechanism Paper Tray Host Driver Software Communicate with Host Command Printer Functional or Physical Elements Chunks Connect to Host Logic Board

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

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 User Interface Board Styling Thermal Distortion Paper Tray Vibration Print Mechanism Logic Board Host Driver Software RF Interference Thermal Distortion RF Shielding Chassis Power Cord and “Brick”

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.

Figure 9.10

Delayed differentiation

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

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

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)

Design for Assembly Old seat frame Redesigned seat frame 9 components 20 operations 30 min to assemble 4 components 8 operations 8 min to assemble

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

Nail clipper with one interface 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

A single base for locating 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

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

Design for Assembly Guideline 6: Modifications to avoid tangling Guideline 6: Avoid component characteristics that complicate retrieval Tangling

Design for Assembly Nesting Modifications to avoid nesting

Modification of parts for end-to-end symmetry 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) Modification of parts for end-to-end symmetry 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

Design for Assembly 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 Adding a hole and rounding the end

Design for Assembly Modification of a part for symmetry

Modification of parts to force asymmetry Design for Assembly Modification of parts to force asymmetry 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)

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

Design for Assembly Use of chamfers (rounded corners) to ease assembly Guideline 12: Make use of chamfers, leads and compliance to facilitate insertion and alignment Each component should guide itself into place

Design for Assembly Use of leads to ease assembly Use of compliance to ease assembly

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

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

Design for Maintenance 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

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

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.

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

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