Configuration Design What is a product configuration? What is a part configuration? Product architecture design Part configuration design Evaluating Configurations Computer Aided Design Solid modeling

What is configuration design? For example: Design problem: reduce speed ---- Concept: gear pair What are some possible “configurations” for a gear pair? geometry & materialPhysical principle

Alternative configuration #1 arrange parts differently

Alternative configuration #2 Spur gearsHelical gears use different features or parts

Configuration #3 and #4 use different relative dimensions wide teethsimilar diameters

What is a part configuration? For example: Design problem: support vertical load ---- Concept: wall bracket What are some possible “configurations” for a wall bracket? geometry & materialPhysical principle

Wall bracket configurations different features alternative arrangements different relative dimensions Abstract embodiment

Configuration decisions Change one or more of these… How do we create different configurations?

Obtaining the “best” configuration To be selective, we need a selection! How should we start our configuration design efforts? To choose the “best” alternative…. Implies that we have a number of feasible alternatives!

Use the design process as a guide? Establish functional requirements Determine constraints Set performance targets Generating Alternatives Formulating Problem Analyzing Alternatives Evaluating Alternatives Create alternative forms (shape, configuration, size, materials, manufacturing processes) all alternatives feasible alternatives Redesign iteration Design specifications best alternative design candidate Manufacturing specifications

Configuration design Configure Part(s) Configure Product Analyze and Refine Iterate Re-examine EDS Research sources Configuration requirements sketch Best concept(s) Design for Function Design for Assembly Design for Manufacture Best configuration(s) Pugh’s Method Weighted Rating Method Evaluate Product architecture Integral / modular Standard / special purpose

Product architecture …like house architecture Architecture styleScheme colonial dining, living rooms 1st floor bedrooms on 2 nd floor ranchall rooms on ground floor Rooms are arranged according to a logical “scheme.” Before the details of all the house are designed we determine the general layout or “architecture.”

Recall: penlight component decomp. diagram penlight bulb battery body spring screw cap glass lens filament base anode cathode electrolyte plastic cover switch case elements are arranged into “physical building blocks”

Generalized component decomposition Product Subassembly A Standard Part Standard part Special purpose part Special purpose Part Subassembly B Special purpose part Subassembly B1 Standard part Special purpose part a. type, number, arrangement of components b. standard or special purpose (make or buy)

Product Architecture def – the scheme by which the functional elements of a product are arranged into physical building blocks (components, subsystems or subassemblies) that interact with each other to perform the overall function of the product. Product architectures can be “ modular ” or “ integral ”

Modular architecture Product examples Flashlight Refrigerator Automobile Personal computer Modular components Batteries, bulbs Motors, compressor, switches Tires, radios, seats, pumps engines Drives, keyboards, mice, modems chunks implement one or a few functions, interactions between chunks are well defined (standard interfaces / connections)

Integral Architecture Product examples BMW Motorcycle engine Printer case Shaft Beverage cup Integrating aspects engine/frame integral snap-fasteners machined bearing race integrated handle a single chunk implements many functions interaction is ill defined physical element “shares” functions

Steps for developing a product architecture 1. create a schematic of functional and physical elements 2. cluster elements into logical chunks to: exploit standard components to exploit standard interfaces (e.g. 120 VAC, RS232 ) fully utilize manufacturing process(es), or vendors provide for maintenance 3. sketch a rough geometric layout 4. identify interactions between elements 5. refine layout

Printer Example

Cluster elements into logical chunks

Sketch rough geometric layout

Sketch interaction diagram

Part configuration design Configure Part(s) Configure Product Analyze and Refine Iterate Re-examine EDS Research sources Configuration requirements sketch Best concept(s) Design for Function Design for Assembly Design for Manufacture Best configuration(s) Pugh’s Method Weighted Rating Method Evaluate Product architecture Integral / modular Standard / special purpose

Part configuration design geometric features include: wallsroundscubesnotches ribsbossessphereschamfers projection s cylindersholesgrooves filletstubesslots

How can we “generate” alternative part configurations? different features alternative arrangements different relative dimensions Abstract embodiment Recall bracket configurations

Example: configuring a sponge holder Step 1. Prepare configuration requirements sketch sponge holder Step 2. Prepare non-contiguous config. requirements sketch

Step 3. Prepare alternative contiguous configuration sketches

Step 4. Refine configurations with hole in back wallwith hole in offset wall

Configuration design - analysis Configure Part(s) Configure Product Analyze and Refine Iterate Re-examine EDS Research sources Configuration requirements sketch Best concept(s) Design for Function Design for Assembly Design for Manufacture Best configuration(s) Pugh’s Method Weighted Rating Method Evaluate Product architecture Integral / modular Standard / special purpose

To analyze configurations, we ask… Will it function? Will it assemble? Will it be manufacturable?

Design for function 1. Strong 2. Stiff or flexible 3. Buckle 4. Thermal expansion 5. Vibrate 6. Quiet / Noise 7. Heat transfer 8. Fluids transport / storage 9. Energy efficient 10. Stable 11. Reliable 12. Human factors/ergonomics 13. Safe 14. Easy to use 15. Maintain 16. Repairable 17. Durable (wear, corrosion) 18. Life-cycle costs 19. Styling/aesthetics Will the part or product perform its function(s)?

Will it assemble? Assembly - a process of handling components to bring them together (inserting) and then fastening them. What do we mean by assemble?

Reduce handling 1. Handling - (GMOP: grasping, moving, orient, place). design parts or products to reduce the influence on handling: size, thickness, weight, nesting, tangling, fragility, flexibility, slipperiness, stickiness, need for 2 hands, tools, optical magnification or mechanical assistance.

Reduce inserting and fastening effort 2. insertion & fastening - mating a part to another part or sub-assembly. design parts and products to reduce the influence of: accessabilityresistance (force) to insertion visibility ease of alignment & positioning depth of insertionseparate operation required fastener used

DFA Design for Assembly - a set of design practices which reduce the manpower time required to handle, insert and fasten components of a product.

Design for Assembly Guidelines from SME minimize part count minimize levels of assembly (number of assemblies) encourage modular assembly use standard parts stack sub-assemblies from the bottom up design parts with self-fastening features (snap-fits, press-fits) facilitate parts handling (grasp, orient, move) design parts with self-locating features (e.g. chamfers, aligning recesses/dimples) eliminate reorientation (i.e. insertion from 2 or more directions) eliminate (electric) cables

DFA Graphical 1

DFA Graphical 2

DFA Graphical 3

DFA Graphical 4

Pros and cons of DFA methods 1. Design Guidelines pros: fast, easy, non-coupled cons: non-quantitative, can’t compare alt. designs 2. Assembly Efficiency (Boothroyd & Dewhurst) E ma = theoretical min. assembly time estimated assembly time pros: systematic, comparative cons: takes time to code & calculate

DFM Deign for Manufacture (manufacturability) - A set of practices that aim to improve the fabrication of individual parts 1. Design Guidelines (written and graphical) 2. Cost estimating methods (difficult w/o dimensions)

DFM – Injection molding / casting avoid designing parts with thick walls or heavy sections design parts without undercuts choose material for minimum total part cost (i.e. tooling, processing, material) design external threads to lie on parting plane/surface add ribs for stiffening

DFM – Sheet metalworking avoid designing parts with narrow cutouts or projections minimize manufactured scrap (cut-off versus blanking) reduce number of bend planes keep side-action features to a minimum or avoid completely

DFM - Machining employ standard features (e.g. holes, slots, chamfers, fillets, rounds) use raw material available in standard forms (e.g. sheet, roll, bar, plate) avoid sharp internal corners on turned parts specify liberal tolerances and surface finishes

Obtaining the “best” configuration To be selective, we need a selection! How should we start our configuration design efforts? To choose the “best” alternative…. Implies that we have a number of feasible alternatives!

Configuration design - evaluation Configure Part(s) Configure Product Analyze and Refine Iterate Re-examine EDS Research sources Configuration requirements sketch Best concept(s) Design for Function Design for Assembly Design for Manufacture Best configuration(s) Pugh’s Method Weighted Rating Method Evaluate Product architecture Integral / modular Standard / special purpose

Let’s evaluate the Sponge holder configurations with hole in back wallwith hole in offset wall

Evaluation using Weighted Rating Method 1.List evaluation criteria (in a column). 2.Determine importance weights (in an adjacent column) 3.List alternatives (along the top row) 4.Rate each alternative on each criterion 5.Compute the weighted rating for each criterion 6.Sum the ratings to produce the Overall Weighted Rating

Evaluating alternative configurations

Configuration design summary Configure Part(s) Configure Product Analyze and Refine Iterate Re-examine EDS Research sources Configuration requirements sketch Best concept(s) Design for Function Design for Assembly Design for Manufacture Best configuration(s) Pugh’s Method Weighted Rating Method Evaluate Product architecture Integral / modular Standard / special purpose

Using graphics during configuration design Sketches are used often in configuration design Sketches assist creativity Sketches are not typically used to “document” the “design” CAD Drawings need sizes (e.g. H, W, L, D) CAD Takes time But, some CAD may be useful

CAD Compact disk – demo of solid modeling

Computer Aided Design – data models 2-D model: (x1, y1), (x2, y2), faceted curves Wireframe model: (x1,y1,z1), (x1, y2, z2) Surface model: (pts, surface data) Solid model: (solid primitives, Boolean op’s)

Advantages of solid modeling Design intent is captured- such as holes moving with bosses Feature-based modeling– automating with features such as chamfer, fillet, flange-bolt Constraint-based– geometric relations Parametric- dimensions are placeholders Fully Associative- one model controls all views Assemble-ability check– interference, motion Downstream benefits- CAE, FEA, CAM, rapid prototyping

Summary Product configuration Part configuration Product architecture design Part configuration design Analyzing configurations Evaluating configurations Computer Aided Design Solid modeling