The Product Development Process – Step 5 – Prototypes

The Product Development Process

build a prototype


Step 5 – The Purpose of Prototypes

Prototyping is the Design Verification phase of Product Development because it demonstrates or proves the design.  Think of Prototypes as simply taking a design from the virtual, imaginary realm into the physical world.

Why Prototype?

Of course there are lots of reasons we want to touch and feel and try our new widget, and a prototype is the way to do that. But, there are some specific reasons to prototype.  Some of the most common are:

  • Display or Show the new product — maybe at a show or for investors.
  • Test an idea to see if it really works.
  • Test the design to see if it passes certain requirements.
  • Use it to evaluate where improvements are necessary.
  • Get customer feedback.

I lump prototypes into 2 categories:  1. Looks Like;  2. Works Like.  Basically that’s prototypes that look and feel complete (but may not actually function); then prototypes that function properly (though maybe not as strong, and may look like crap).  Of course, there’s the combination version that both Looks right and Functions correctly. Those are finals.

With the concepts of “Functional” and “Display” types in mind, there are many levels of Prototypes:

  • Some are simple duct-tape and bailing wire types to visualize how something might work;
  • Then there are clay or paper mache to show in a rough way what it might look like;
  • Still others are functional representations that work, but may not look very good;
  • 3D printed prototypes may look the part and may also function, but not a full capacity;
  • Some are high polish, fragile representations for show and tell;
  • And some are complete representations of the final product.

And, there are many more. All of these are great to reach a specific goal. So, whatever reasons for building one, choose a prototype to fit the purpose. Let your project or tests determine which is right — especially since there is often significant cost.

Prototyping Methods

Traditional prototyping methods include mock-ups (clay, wood or other), fabrication, and of course, the infamous bailing wire and duct tape.  More modern methods include CNC and rapid prototyping (like 3D Printing, SLA, SLS and many more).  Mock-ups are typically early in the design for visualization, feel, and to allow adjustments or fiddling with shape and size.  Fabricated prototypes are typically functional versions that may or may not look like the final product but give the opportunity to test function or prove something works.

CNC is a modern method just because the advances in CNC work continue to improve.  Most people think about CNC with respect to metal parts, but plastic is common too.  The big advantage of CNC is structural integrity of the parts.  If you need to test strength or deflection situations, CNC may be the best option.

The term Rapid Prototyping encompasses a large group of technologies that create 3D physical parts directly from the computer.  This is becoming very popular because of the speed and accuracy available.  These can be done in almost any shape and can be finished to look exactly like a production part, though usually they are much more fragile.  A whole host of service bureaus have sprung up to meet this need, as well as 3D printers and ever expanding materials and technologies.  For more information, a quick web search will usually yield an overload of information.

Regardless of the method, prototypes are tools:  for learning, for visualization and for design improvement.  Think of them this way, and it will mean more.

When To Prototype

Before diving into the prototyping phase, there are few questions to ask:

  • Is a prototype desirable or necessary?
  • Does the need for design verification justify it?
  • Is testing needed for design improvement?
  • Does the design reflect the best knowledge before prototyping?
  • What kind of prototype will fill the needs best?

Depending on the product, a prototype may or may not be necessary — or perhaps more importantly, it may be that only portions of the design need prototyping.  This does not to say prototypes are not important. It’s mention is to emphasize that prototyping is costly in both time and money so the need is worth evaluating.

In many industries the products are quite complex and require several iterations of design, prototyping and testing.  The auto industry, for instance, uses several variations of prototypes to evaluate the design and to find areas of improvement.  In the case of automobiles, the complexity of the design, the quantities sold, and the amount learned in testing from each version easily justify the time and cost.  Another key example from automotive is the amount of testing that happens at the component level. They don’t test the complete new car until the major subsystems are each proven.

A Note About Testing

What do you test?  How much testing?  What kinds of tests?

Most industries have standards to meet or requirements to satisfy.  Certainly testing is to certify or “pass” requirements, but don’t forget testing for your own benefit.  Run tests to verify your FMEA (Failure Mode Effects Analysis).  Every product has some possible failure point.  It may be in abuse or something else, but because it can fail, you must understand it.  Testing to verify failure effects is extremely important.

Test with an open mind.  Testing should be done as realistically as possible, with a mind open to learning everything available.  If the unexpected happens, then you’re learning. If something breaks, it does not mean YOU failed, it means you’re LEARNING. Furthermore, it means you’re that much closer to a better design.

Don’t skip or short-cut the testing.  Field failures come back to bite — usually with very large teeth!

Production Quotes

A process to run in parallel with prototyping is Production Quotation.  This is where manufacturer input is requested — both for cost to produce as well as for ways the product can be made cheaper, easier, lighter, faster, stronger
and better.  This is especially valuable if the design is in iteration, and that can influence your needs in prototyping.  Use the prototypes to work with manufacturers for the best possible input and prices.

In practice, most products require at least one prototyping phase.  Typically, the flow is from the design phase to prototype and testing then back to design for (hopefully) minor changes before going to production.  The final design phase is much better when it includes information from the production quotation process.

Prototyping  (our Speaker Example)

The first speaker prototype turned out well, verifying the design.  Then, a matching prototype was made with very few modifications, and both are in use.  A few improvements for ease of assembly were identified, so some minor changes were made in the design, then plans were set for sale.  Those plans are currently available on the Mechanical Elements website.

Concluding Thoughts . . .

Really, the Design, Prototyping and Testing steps of the Product Development Process can blur together as one with learning and insight coming from all these tools.  One process feeds the next as iteration perfects the design.  The final stages of both design and prototyping (especially the final stages) are most effective when they include input from manufacturing.

Whatever the product, if it is to be sold, it will need to be produced, and that involves the next step of manufacturing.  Our experience has taught that involving possible manufacturers early in the design & engineering phase and especially through the prototyping phase(s) makes the transition from design to production much easier, faster and smoother.  I suppose many people don’t think about using prototypes this way, but it is really a powerful tool — and it’s almost free if you use a prototype that has already filled it’s need in testing or display.

Continue Trailer DesignNext Up:  Step 6  –  Production Details and Production

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