Choosing A Process

Choosing the best prototyping process depends on where your are in product development and what attributes are most important to success. Determine the process that is the best fit for your project by using the tools shown here. See full definitions of terms below charts.

Step 1: Begin by using the decision tree below to narrow down which factors are of highest importance to you based on the stage you are at in the prototyping process, referring to the definitions.

Step 2: Based on the recommended attributes for your most important factor(s) from Step 1, compare the processes using the matrix to determine which process will be the best fit for your project.



Definitions vary and may differ at different organizations, but the definitions below may be used as a starting point.

Concept Model – A crude physical model made to demonstrate an idea. Concept models allow people from different functional areas to see the idea, stimulate thought and discussion, and drive acceptance or rejection.

Important prototyping attributes:

  • Speed – turnaround time to convert a computer file into a physical prototype
  • Appearance – any visual attribute – color, texture, size, shape, etc.
  • Assembly / Fit Test – making some or all of the parts of an assembly, putting them together, and seeing if they fit properly. At the gross level, this checks for design errors, such as placing two tabs at 2” spacing and the mating slots at 1” spacing. At the fine level, this is a matter of minor dimensional differences and tolerances. Obviously any test involving tolerances needs to use the actual manufacturing process or one which has similar tolerances.

Important prototyping attributes:

  • Form – the shape of the part – features and size
  • Fit – how the part mates with other parts.
  • Functional Testing – seeing how a part or assembly will function when subjected to stresses representing what it will see in its actual application.

Important prototyping attributes:

  • Chemical Resistance – resistance to chemicals including acids, bases, hydrocarbons, fuels, etc.
  • Mechanical Properties – strength of the part measured by tensile strength, compressive strength, flexural strength, impact strength, tear resistance, etc.
  • Electrical Properties – interaction of electrical fields and the part. This may include dielectric constant, dielectric strength, dissipation factor, surface and volume resistivity, static decay, etc.
  • Thermal Properties – Changes in mechanical properties that occur with changes in temperature. These may include thermal expansion coefficient, heat deflection temperature, vicat softening point, etc.
  • Optical – ability to transmit light. May include refractive index, transmittance and haze.
  • Life Test – testing properties that may change with time and that are important for a product to remain functional throughout its expected life. Life testing often involves subjecting the product to extreme conditions (e.g. temperature, humidity, voltage, UV, etc) to estimate in a shorter period of time, how the product will react over its expected life.

Important prototyping attributes:

  • Mechanical Properties – fatigue strength – ability to withstand large numbers of load cycles at various stress levels.
  • Aging Properties (UV, creep) – ability to withstand exposure to ultraviolet light with an acceptable amount of degradation; ability to withstand extended applications of forces to the part with acceptable levels of permanent deflection.
  • Regulatory Testing – testing specified by a regulatory or standards organization or agency to assure parts are suitable for a particular use such as medical, food service or consumer application. Examples include Underwriters Laboratory (UL), the Canadian Standards Association (CSA) the US Food and Drug Agency (FDA), the US Federal Communications Commission (FCC), the International Standard Organization (ISO) and the European Commission (EC).

Important prototyping attributes:

  • Flammability Properties – the resistance of a resin or part to ignition in the presence of a flame
  • EMI/RFI Properties – the ability of a resin, part or assembly to shield or block Electromagnetic Interference or Radio Frequency Interference
  • Food Rating – approval of a resin or part to be used in applications where it will come in contact with food while it is being prepared, served or consumed.
  • Bio-compatibility – the ability of the resin or part to be in contact with human or animal bodies, outside or inside the body, without causing undue adverse effects (e.g. irritations, blood interactions, toxicity, etc). Bio-compatibility is important for surgical instruments and many medical devices.

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