Prototyping -syde361 Zelek

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Regina Ginger Copeland
5 years ago
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1 Prototyping -syde361 Zelek a physical model is a fabricated object to appreciate aspects of HOW a product will perform (FUNCTION) or look (FORM) or both!

2 to consider when prototyping should team build a a certain time what is purpose of prototyping effort? what are possible forms of prototype? what simplifications can be made independent of the prototyping purpose? what type of tests applied to prototype? what is risk of constructing prototypes or continuing without them? 2

3 6 general classes of prototypes typically used 1. proof-of-concept models 2. industrial design prototypes 3. DOE (design of experiments) experimental prototypes 4. alpha (same geometry & material, different manufacturing) prototype 5. beta (final product production, special assembly) prototype 6. pre-production (pilot production, limited capacity) prototype NOTE: don t always have to build the whole thing, maybe just a critical part, function usually precedes style but not always 3

4 uses of prototypes 1. communications - to obtain feedback from customers, suppliers, vendors & management 2. demonstration - show accomplishment of project goals & milestones, especially to customers, clients & investors 3. scheduling/milestones - to force preliminary designs and to avoid terminal cycles in concept development & embodiment design 4. feasibility - to focus on specific ideas, to determine if they satisfy customer needs, and to uncover unpredicted phenomena. Measurements typically recorded & analyzed. 5. parametric model - to systematically develop a phenomenological model of the product or subsystem. Experimentation is required and the results lead to decisions for design variables to optimize performance. 6. architectural interfacing - to determine if module interfaces perform properly, to test compatibility, & assembly of components & to explore manufacturing processes & standard part issue. 4

5 decision trade-off between analytical & physical models high model it model it difficult problem model accuracy/ prototype accuracy model it does not matter prototype it low difficult problem prototype it prototype it low model expense/ prototype expense high 5

6 physical vs. analytical prototypes physical prototypes tangible approximation of the product may exhibit unmodeled behavior some behavior may be an artifact of the approximation often best for communication analytical prototypes mathematical model of the product can only exhibit behavior arising from explicitly modeled phenomena (however, behavior is not always anticipated) some behavior may be an artifact of the analytical method often allow more experimental freedom than physical models 6

7 focused vs. comprehensive prototypes focused prototypes implement one or a few attributes of the product answer specific questions about the product design generally several are required comprehensive prototypes implement many or all attributes of the product offer opportunities for rigorous testing often best for milestones and integration NOTE: always get as much feedback you can from a prototype before revising or new version! 7

8 mock up materials and processes - prototype criteria 1. cost minimized, risks of material selected, material advantages for testing 2. availability readily available materials (raw, stock, off-the-shelf) to avoid delays 3. ability to accept change choice of materials should accommodate modifications in dimensions, surface requirements, ease of use & form capability special tools, safety equipment, fixtures & setup shoudl be avoided; material should be relatively easy to form 5. scalable geometry simplified & convenient prototype shapes 6. scalable properties to actual production? e.g., mechanical (strength, endurance limit, durability, wear), thermal (conductivity, mass & expansion coefficient), electrical (inductance, resistance) & chemcial (corrosion resistance)

9 examples of materials wood & wood products plastics metals adhesives others

10 prototyping processes handworking techniques (hand, hand tools, knives, sanding blocks & small power tools expoxy molds CNC machining cast metal molds machined aluminum molds injection molding vacuum forming silicon rubber (RTV) molds electronic breadboarding mechanical breadboarding rapid prototyping

11 choosing RP (rapid prototyping) cost trade off cycle time (& speed of fabrication) accuracy of prototyped parts material prototypes part size, strength

12 pine wood for prototyping good overall modeling material inexpensive easy to tool hardwoods (oak, cheery, birch, mahogany, etc. generally higher quality than pine in terms of appearance, absence of knots, etc. makes more precise joints holds fasteners better higher load capability plywood high strength available in large sheets both hardwood and softwood varieties choice of grades

13 wood for prototyping (2) balsa light weight low strength (in general, but good static strength along grains) versatile and easy to form (hand tools) wood products (particle board, pressboard, hardboard, etc.) wood products impregnated with resins very dense available in sheets

14 prototyping with plastics ABS (Acrylonatrile Butadeine Styrine) good for structural applications thermoformable bonds well high impact strength, good fracture resistance expensive available in sheets and rods Polymethyl methacrylate (plexiglass) excellent optical clarity good impact strength and durability easy to tool bonds with cyanoacrylate (super glue) Polycarbonate (lexan) high impact strength high tensile strength transparent in thickness up to 1/2 available in colors available in sheets, rods, tubes and film

15 prototyping with plastics (2) Polystyrene relatively brittle easy to mold useful in sheets: 1/64, 1/32, 1/16, 1/8 thickness tubing, strips, sheets and extruded shapes are available Acrylic useful in sheets transparent applications fairly brittle Nylon low coefficient of friction high strength FDA approved for medical and food processing applications available in sheets, bars, rods and tubes (bushings)

16 prototyping with plastics (3) Delrin machines well durable, excellent toughness resists many solvents does not bond well available in sheets, rods, bars and strips Teflon low coefficient of friction high impact resistance FDA approved for medical and food processing applications available in sheets and rods Ultra high molecular weight polyethylene low coefficient of friction poor person s Teflon available in sheets, rods and tubes

17 prototyping with plastics (4) redwood wood-like material easy to work with hard-urethane foam (last-a-foam) very easy to work with good for dimensional mockups and layout planning available from general plastics, Tacoma, Wash. bondo epoxy-like material used in automotive bodywork good for filling gaps and providing smooth contours over most metals widely available phenolic (garolite) inexpensive, durable nice finish higher temperature capability

18 prototyping with metals aluminum machines well high strength-to-weight ratio corrosion resistant difficult to weld available in variety of alloys, heat treatments, and shapes brass machines well (self-lubricating) can be brazed corrosion resistant relatively expensive available in sheets, rods, bars, and extrusions steel high strength welds easily available in extrusions (angles, etc) and bar stock lead very dense low melting temperature easy to mold toxic - care must be taken to dispose of properly available in sheets, bricks, shot, discs, and ingots

19 prototyping with adhesives cyanoacrylate (super glue) quick drying joins almost anything, although will not work on polypropylene discolors clear plastics activators (spray or applicator brush) will result in immediate setup) contains harmful volatile organic compounds wood/white glue versatile strong joint when impregnates materials and clamped requires long setup time good as a secondary fastening method hot-melt glue convenient and versatile low strength fast setup epoxy base material and a catalyst, mixed before use very strong joint sets relatively quickly contains harmful volatile organic compounds

20 prototyping with adhesives-2 methyl chloride solvent to join plastics works well with ABS and polystyrene trichloroethane (contact cement) convenient and versatile, joins most anything 30 minutes drying time contains harmful volatile organic compounds silicone (shoe goop TRV) translucent clear or colored convenient and versatile weak joints will bond with fabric and polypropylene contains harmful volatile organic compounds spray mount adhesive in a spray can useful for adhering paper or plastic labels, lettering contains harmful volatile organic compounds

21 prototyping with misc. materials modeling clay easy to work with hands and hand tools useful for visualization and air flow studies always remains soft available in hobby and craft shops machining wax machines well useful for patterns for prototyping tooling foam core easily carved good finish useful for painting (aesthetic/appearance models) machinable pressurized cans of insulating foam available that harden quickly and may be cut and formed with a knife & sanding board rubber, elastomers useful in energy absorption applications or seals can be used as a removable molds for castings of other materials can be carved

22 prototyping with misc. materials-2 fibreglass good strength low weigt variety of shapes requires lay-up process and drying Solarez as a filler compound dries in minutes of direct sunlight easily finished cardboard, paper, cloth use foam core instead of cardboard cloth and paper can serve as joints in mockups very cheap

23 guidelines during prototype development Judge the risk of not creating a prototype vs. cost and build time. If there exists minimal risk, proceed forward without the physical prototype. If a prototype is needed, don t be tenuous in its fabrication, but move ahead with enthusiasm. Each prototype simply adds to a strong foundation for creating a successful product. During proof-of-concept, prototype the difficult, trickiest components first. These undoubtedly will be the weaest links in the product concept. Draw, sketch, or create a solid model of the prototype at an appropriate level of detail. For electronic prototypes or subsystems, wire-wrapping and bread-boarding work well. Stick to basic machines.

guidelines during prototype development-2 Use off-the-shelf components when possible. Remove features from the prototype that are not necessary for the tests.

24 guidelines during prototype development-2 Use off-the-shelf components when possible. Remove features from the prototype that are not necessary for the tests. Know the catalogs: Thomas Registry, McMaster-Carr, Edmund Scientific, Digikey,... Hardware stores, novelty stores, and product catalogs are great sources for ideas and parts. Scavenge parts from similar or analogous products when developing early prototypes. Prototyping with molds, at low cost, is possible. Rapid prototyping is not always rapid and is not always cheaper. Comparisons must be made with other technologies. Dual prototypes at a given stage of the product development process are common if a singular prototype cannot be fabricated to satisfy multiple purposes. Be willing to create 2 or more simple prototypes instead of one that is overly complex.

Engineering 7936 Design Project

Engineering 7936 Design Project Prototyping 1 Introduction Prototype = an approximation of the product along one or more dimensions of interest. Alpha prototypes: Used to assess whether product works as