Prototyping and Proofing a Design.

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Prototyping and Proofing a Design
MEC
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Contents

• Prototypes.
• Models.
• Proof of Concept.
• Testing Prototypes and Models.
• 3D Representation.
• Constructing Models and Prototypes.

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Prototypes, models, and proof-of-concept testing
have different roles in engineering design
because of their intents and test environments.
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Prototypes

• Original models on which something is patterned.
• First full-scale and usually functional forms of
  a new type or design of a construction.
• Working models of designed artifacts.
• To be tested in the same operating environments
  in which theyre expected to function.

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Models

• A miniature representation of something, or a
  pattern of something to be made, or an example
  for imitation or emulation.
• Represent some devices or processes.
• May be paper models or computer models or
  physical models.
• Illustrate certain behaviors or phenomena as we
  try to verify the validity of an underlying
  (predictive) theory.

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Models

• Smaller and made of different materials than are
  the original artifacts they represent.
• Tested in a laboratory or in some other
  controlled environment to validate their expected
  behavior.

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Proof of Concept

• A model of some part of a design.
• Used specifically to test whether a particular
  concept will actually work as proposed.
• Doing proof-of-concept tests means doing
  controlled experiments to prove/disprove a
  concept.

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Prototype Model
To demonstrate that a product will function as designed. Tested in actual/similar operating environments/ uncontrolled environments close to the relevant real worlds as possible. Made of same materials, size, shape, configuration. First of its kind. Allow the model builder/ designer, to understand the particular behavior or phenomenon. Tested in controlled environments. Likely be much smaller, part of a large system. Represents a device or a process.
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Testing Prototypes and Models

• Proof of concept testing - a new concept, or a
  particular device or configuration, can be shown
  to work in the designed manner.
• Laboratory demonstrations of wing structures and
  building connections can be considered as
  proof-of-concept tests.
• Market surveys of new products (samples mailed
  out or stuffed into sacks) conceived of as
  proof-of-concept tests.

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Proof of Concept Testing

• Turning on a new artifact and seeing whether or
  not it works not a proper proof-of-concept
  demonstration.
• Reasoned and supported hypotheses tested,
  validated or disproved.
• Experiment to be designed, hypotheses to be
  disproved if certain outcomes result.
• Controlled tests for models, prototypes.
• Doing controlled experiments, failure to disprove
  a concept may be key.

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3D Representation

• To translate design ideas into models and
  prototypes that can be used to test design
  concepts and communicate ideas to the client.
• Sketching or drawing representations to create
  the prototype or model.
• A three-dimensional (3D) representation of the
  designed object using a software program.

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Use of 3D Representation

• as an input to a computational modeling
• program to simulate the designs performance
  under specified conditions.
• (2) as an input into a variety of rapid
  prototyping technologies, such as 3D printing.
• (3) to generate detailed engineering drawings of
  the design.
• (4) to guide the tool path in computer
  numerical-controlled (CNC) machining.

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When to build a Prototype?

• Decision depends on
• size and type of the design space.
• costs of building a prototype.
• ease of building that prototype.
• role a full-size prototype might play in ensuring
  the widespread acceptance of a new design.
• number of copies of the final artifact expected
  to be made or built.

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Prototypes

• No obvious correlation between the size and cost
  of prototypingor the decision to build a
  prototypeand the size and type of the design
  space.
• Strongly influenced by the relative ease of
  building.
• Project schedule and budget to reflect plans for
  building them.
• May be instances in which resources or time are
  not available.

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Prototypes

• To model behavior that needed to be understood as
  part of completing the overall design.
• Good idea to build a prototype if cheap and easy
  to do.
• Prototypes of parts of large, complex systems to
  use as models to check how well those parts
  behave or function.
• Computer-aided design and analysis to replace
  some elements of prototype development with
  sophisticated simulation.

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Who will build Prototype?

• Choice of assemble in-house or outsource.
• Decision to depend on expertise, expense, and
  time.
• Need machinists, electronics technicians, and
  programmers on staff for building models.
• Need to own machine shop and machine it urgently,
  say in an hour.

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Who will build Prototype?

• Good idea to try to give the machinists
  meaningful lead times, to ask their advice often,
  and to not ask for things that are silly or
  impossible.
• May still be cheaper and/or faster to have
  specific items outsourced.
• Will go much more smoothly with detailed
  specifications for what we are outsourcing.

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Parts and Components

• Parts and components best bought from suppliers,
  unless we happen to be in the business of
  designing and making those particular items.
• Common mass-produced items should always be
  bought.
• Good idea to check the institutions stockroom(s)
  to see if parts are already available before
  buying.

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Parts and Components

• Fasteners and common mechanical parts or devices
  may be bought.
• Electronic, electromechanical and optical
  components may be bought.
• Online orders to ensure speedy delivery.
• Can make use of search capabilities and real time
  inventories to place orders.

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Constructing Prototypes

• Need for detailed, annotated drawings and plans
  before we start cutting or machining.
• Ensuring that things fit together the very first
  time they are assembled.
• Minimize reworking the problem or the parts.
• Preparing bill of materials during a virtual or
  paper assembly.
• Identify all of the necessary parts before
  everything has been done.

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Constructing Prototypes

• Checking the availability of the parts to help
  scheduling.
• Constructing a process router, a list of
  instructions for fabricating and assembling
• prototypes.
• True prototypes made from same materials intended
  for the final design.
• Materials may change for the final design.

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Constructing Models

• Model can be constructed from whatever material
  will assist in answering the questions the model
  was designed to pose.
• Materials include paper, cardboard, wood,
  plywood, polymers (such as PVC, ABS, polystyrene,
  and acrylic), aluminum, and mild steel.

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Constructing Models and Prototypes

• Choice to depend on the cost, timing, and
  complexity of the design.
• Choices include
• Mockups of a design from 2D shapes.
• Machine parts directly.
• CNC machine parts.
• Use rapid prototyping technologies.

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Mockups

• Constructing a mockup of a 3D part from 2D
  cutouts.
• For making basic models or prototypes.
• 2D parts can be made using a vinyl cutter or a
  laser cutter.
• Parts then assembled into 3D mock-ups of a
  design.
• Materials used for mock-ups might be foam, thin
  plastic, or wood.

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Machining

• Separate machine shops for woodworking and
  metalworking.
• Woodworking machines include drill presses for
  making holes, band saws for cutting at various
  angles, and lathes for reducing diameter and
  creating parts with symmetric curved surfaces.

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Machining

• Metal shop includes lathes for reducing diameter
  of a part, tapping a hole or facing an end, and
  mills for creating slots, holes, and flat
  surfaces.
• Simpler to use CNC machining to produce complex
  parts.
• CNC machines to produce very small objects or
  very large objects in a range of materials.

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Machining

• CNC machines to use 3D computer-aided design
  (CAD) models and/or drawings of the part to
  create a step-by-step machine log in.
• A software program to input into the CNC machine.
• Safety in the workshop critically important.
• Power tools may cause dismemberment and death.

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Injection Moulding

To produce parts by injecting molten material
into a mould or mold. Can be performed with
metals (process called die-casting), glasses,
elastomers, confections, thermoplastic and
thermosetting polymers.
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Rapid Prototyping

• Faster and cheaper alternative to injection
  moulding for creating prototypes.
• Use of 3D CAD models as inputs.
• Converting 3D files into thin 2D layers to build
  the 3D part.
• Includes stereo-lithography and selective laser
  sintering.
• Laser sintering to use lasers to harden either a
  resin bath or a polymer powder in a particular
  configuration to build each layer.

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Fused Deposition Modeling

• Uses standard engineering thermoplastics.
• Eg acrylonitrile butadienestyrene (ABS)
  impact resistant and tough 3D Printing.
• A heated filament of a particular material
  squeezed out of a tube one layer at a time onto a
  stage.
• Stage then moved down a fixed increment and
  another layer completed.
• More than one material can be used at once.

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3D Printing

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Reference

• Clive L Dim, Patrick Little and Elizabeth J
  Orwin, Engineering Design, A Project Based
  Introduction, 4th Edition, Wiley, U.S.A, 2014.

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Thank You