Presentation on theme: "Building and testing prototypes"— Presentation transcript:
1 Building and testing prototypes Why test?Form, fit & functionTypes of testsTypes of prototypesTest plansSummary
2 Why Do Product Testing?Finished parts do not always look the same as designedFinished parts do not always fit together as designedFinished parts do not always work the way they were designed.
3 What do “form” tests determine? Form test– Will the part/product have an acceptable appearance?
4 What do “fit” tests determine? Fit test – Will the parts fit together or fit the user, with an acceptable precision?
5 What do “function” tests determine? Function – Will the part/product perform as required?
6 Tests: Types & Timing -A FormulationConcept Design“Proof of Concept” testsvalidate physical principles“Product Concept” testsvalidate product / appearance
7 Product concept and Proof-of-concept models Mercedes F700
8 Tests: Types & Timing - B Parametric DesignConfiguration Design“Virtual prototype” testssolid modeling CAD“Alpha prototype” testsactual geometry & materialsbut may not use actual mfg. processes
9 Virtual prototypeMercedes F700MIT Smart City 2020
10 Alpha prototype The flying saucer Sky Commuter is on the block on ebay. Starting bid: $55,600.Labels: Future Past, TechnologyThe flying saucer
11 Tests: Types & Timing - C Detail DesignManufacture“Beta prototype” testsparts made with planned mfg. processesvolunteer customers / panelactual operating conditions, environment“Preproduction prototype” testsparts made with final mat’s & processesindependent labs: UL, CPSC, NHTSA
12 need physical “prototype” Testing SequenceProduct conceptProof of conceptVirtual prototypeAlpha prototypeBeta prototypePreProduction prototypeless expensivemore expensiveneed physical “prototype”
13 More prototypesToyota WingletToyota i-RealToyota i-FootToyota PM
14 Physical PrototypesPrototype… is a replica or model of the part showing principal geometric featuresPrototypes differ in:Scale - Reduced, Full, ExpandedFabrication Process - Same as mfg, Similar, DifferentMaterial - Same as final, Different, SimilarTwo ways to make prototypes:TraditionalRapid
15 Traditional prototypes Clay models of new auto body for appearance testing,Wood models of heavy equipment patterns for metal castings,Manually machined metal airplane wings for function testing in a wind tunnel,Reduced-scale balsa wood models of large facilities, to examine equipment layout.Clay modeling: 1, 2, 3, 4, 5
16 Some Disadvantages of Traditional Prototyping Uses tools and fabrication methods that are labor intensive.Often require significant mechanical or artistic skills.Take a long time to fabricate an original.Revisions may require complete rebuilding of partCostly for duplicates.May not facilitate tooling design and construction
19 Numerical Control Machining (NC/CNC) CAD files are converted to NC – machine instruction codes for automatic machiningPart can be made of metalDimensions have excellent tolerancesMultiple copies of parts can be made easilyPrototyped parts are well suited for form, fit and function testsCNC
20 NC Machined part example Mars rover wheels(Courtesy of HAAS Automation)
25 Stereo Lithography Apparatus (SLA) Parts exhibit superior finishespolymeric prototypes are weaker than metal prototypes (i.e.CNC)Prototyped parts are well suited for form, and fit tests.Some function testing
26 Selective Laser Sintering (SLS) Uses a high power laser to sinter together fusible materials, such as powdered metals, layer by layer.Sintering is the heating and fusing of small particles resulting in a hard bonded material block.The un-sintered powder supports the part as the layers are sintered.SLS
27 Fused-deposition modeling (FDM) process FilamentSpoolHeaterDrive WheelsTableFused PartHead motionTable motionHeadMolten filamentFDM, PDF
28 (Courtesy of Stratasys Corporation) FDM – Stratasys 3000(Courtesy of Stratasys Corporation)
31 Fused Deposition Modeling (FDM) Parts can be made fromhigh strength ABS plastic, impact resistant ABS,investment casting wax, and anelastomer.Prototype parts are well suited for form and fit testing.Some function testing
32 3-D Inkjet prototypingGlue-like binder selectively “printed” onto a layer of dry powder, layer by layer, which dries into a solid prototype.Similar process uses a print head to deposit a thermoplastic material, layer by layer.Quick and inexpensiveThe processes work well as concept modelers.Prototypes have limited dimensional tolerancesSomewhat fragile unless coated with a hardenerPrototypes made with this process are typically not function tested.3DP
33 Z-Corporaton Z406 (“Inkjet”) (Courtesy of Z-Corporation)
38 Laminated Object Manufacturing (LOM) Laminating thin layers of paper, polymer or sheet steel, which have been cut using a numerically controlled laser.LOM prototypes can be sanded to reduce jagged edges, but are not able to be function tested such as for stress or strain due to the allotropic material properties of the laminate.LOM
39 Service BureausProduct manufacturer s the solid model part file to the service bureau, typically as an *.STL file.The bureau uses its software to convert the *.STL file to a “sliced” file format specific to the selected prototyping hardware (i.e. FDM, SLA, SLS, LOM),Part is fabricated along with any duplicates.Part(s) may then be overnight-mailed to the product manufacturer.
40 Which Prototyping Method is Best: Traditional or Rapid? Shape generating compatibility – Can the material be formed into the needed geometric features to adequately represent the part?Function testing validity – Are the material properties representative, or scalable such that the part when reduced (or expanded) in size, can be validly tested?Fabrication costs – Will the prototype costs for materials and labor be acceptable?Fabrication time – How long will it take to fabricate the original and one or more duplicates?
42 Engineering TestsBriefly describe the difference between engineering tests and scientific experiments.Scientific experiments establish relationships between causes and effects. That is, they determine scientific principles. For example, a force exerted on a mass causes it to accelerate (effect).Engineering tests validate the application of principles given specific assumptions. For example, will a given sized motor produce enough torque given the frictional losses in the system.
43 1. Mechanical modes of failure static strengthfatiguedeflection/stiffnesscreep, impactvibrationthermal/heat transfer/fluidenergy consumption / productionfriction (i.e. too much, too little)wearlubricationcorrosionlife, reliability
44 2. Manufacturability concerns process compatibility/precisionprocess technology readinessraw material qualityassembly
45 3. Operation and or maintenance concerns styling/aestheticsergonomicsmaintenancerepairs
46 4. Safety concerns risk to user, products liability risk to consumer /societysafety codes, standards (UL, NHTSA)risk to production worker (e.g. OSHA)National Highway Traffic Safety Administration (NHTSA)Underwriters Laboratories Inc. (UL)Occupational Safety and Health Administration (OSHA)
48 Test plans – written and approved Objectives –list of items (parts, systems, models) to be testedpurposes for which the tests are being conductedWorkscope – narrative description:type of tests,test descriptions/procedures,experimental setup,experimental controls,design of experiments test matrix, andlist of deliverables.BudgetScheduleExamples: 1, 2, 3
49 SummaryCompanies build and test prototypes to ensure form, fit and function.Product development tests include: product-concept, proof-of-concept, virtual, alpha, beta, and preproduction.Prototypes can be built using traditional and rapid prototyping methods and materials.Rapid prototyping methods include NC/CNC, SLA, FDM, LOM, SLS, and 3-D Inkjet printing.Rapid prototyping takes advantage of CADPart and product testing can include tests for: mechanical modes of failure, manufacturability, user operation & maintenance, safety and environmental protection.Product development often requires the preparation and completion of a detailed test plan.