3D Printed Models Can be Misleading

Things are really cookin’! Your startup got some seed funding a few months ago and your product concept is taking shape. A few quick concept drawings in a 3D drawing package, send the file to a 3D print shop (or your own 3D printer) and voila! You take your shiny new 3D model to your investor meeting and what a reception you get: “Wow, that’s amazing! Let’s go to production immediately!”

Oops. Whether or not your investors or you realize it, you have just run into a wall. The train’s going off the cliff, and the expectations you just raised are not likely to happen.

There’s a concept called Pareto’s Law, or Pareto’s rule of 80/20. Interpreted for start-up medical product companies, “It will look like you’re 80% of the way done, when you’re really only 20% of the way done.” The availability of 3D printed models has just made Pareto’s Law a lot more commonplace.

A great-looking concept model is a terrific milestone as long as it’s taken in the proper context. If you’re developing a medical device, you still have a long way to go. If your audience for the presentation, such as your investors, doesn’t understand this and its implications, they’ll naturally think you’re close to production due to the finished look of the model. This lack of understanding can easily turn into disappointment and frustration, and lead to some very unpleasant consequences in the future…one of which could be you possibly losing your job!

The good news is that there are ways to place things in context, and potentially to actually get a bit closer to a producible design, by planning ahead. Here are some pointers:

  • Communicate the realistic likely schedule – with contingencies and iterations – before your presentation meeting.
    • Establish realistic expectations from the beginning, and don’t let your audience get carried away with the “look” of a good model.
    • Plan on things going wrong along the way and have alternatives identified.
    • Put iterations into the schedule from the start. As much as you’d like to think you’ll get it right the first time, it almost never happens.
    • Build in time to meet the regulatory requirements, such as obtaining user input, performing risk and hazard assessment, developing design controls, conducting design reviews, building a Design History File (DHF), conducting verification and validation testing and standards compliance testing, and transferring to manufacturing (including the DMR, the Device Master Record). For more on how to streamline this process, check out the Boulder iQ article on “Eliminating the Gate in the Phase-Gate process.”

3D printed models are a great tool for trying out different aesthetic approaches or for human factors studies. Several variations can be made quickly for usability engineering sessions (e.g., focus groups) before finalizing the design. But make sure the audiences know they’re only for early-stage testing.

It’s common to want to go into production with 3D printed parts. There are several issues with this idea for medical devices, though.

  • If this is a sterile product that will come into contact with the patient, it must be shown to be biocompatible per ISO 10993. This is typically an expensive and time-consuming process, and not all 3D materials will pass these tests.
  • If you qualify a 3D printed product for biocompatibility and then switch to injection molding later, you’ll most likely have to repeat biocompatibility testing, as it will usually be a different material and a different process.
  • 3D printing is a quick and relatively inexpensive way to make a small number of parts, but is not economical for higher volumes. Will you need quantities of 10, 20, 30? Sure, 3D print ‘em. 100? Maybe. 1,000? 10,000? Probably not.
  • If you’re printing an enclosure for a product that will contain electronics, the material must meet standards for electrical and fire safety, and not all 3D printing materials will qualify. Performing the required testing is expensive and time-consuming, so it usually makes sense to do this only on the final component configuration (i.e., materials certified to UL 94-V0 or equivalent standards)

You’ll want to perform Design for Manufacturing (DFM) before you go into production. You might want to consider this for the model you 3D print if you’re sure enough of your design approach. Take into account these factors:

  • 3D printers can print almost anything. That includes parts that have undercuts which could never be released from a production injection mold, and shapes that can’t be reproduced by any other means than 3D printing.
  • If you’re confident in the size and look of your design, you can:
    • include tolerances and manufacturing considerations into the file you print;
    • design for moldability by employing drafts and uniform wall thicknesses in the design;
    • perform GDT (Geometric Dimensioning and Tolerancing) techniques and worst-case stack up calculations to be sure you’ll get interchangeable parts;
    • sometimes accommodate material shrinkage in the 3D printed models if you choose the right materials and adjust your design accordingly.

Pareto’s Law has always been with us. 3D printing just makes it more commonplace. 3D is a great tool for quick models and to test concepts, but don’t let it get you in trouble. That old adage is still true: People don’t plan to fail; they fail to plan.

Peggy Fasano, former Chief Operating Officer, Boulder iQ