Jack Harkins09.10.08
Why the Mantra of "Model Early, Model Often" Still Resonates in Medical Device Design
Jack Harkins
Model early. Model often. Sound familiar? To those in product development and manufacturing, it should. It’s the age-old cliché that sets the basis for practices surrounding prototyping and production. It is used by both product developers and manufacturers. Prototyping options change rapidly, and new technologies crop up as quickly as old ones become obsolete. But this mantra never goes away.
Anyone can prototype, but to understand the reasons behind it and its suitable methods is truly an art. This is where the practice of “model early, model often” can transform itself into a successful business strategy for some companies and remains simply a well-known motto for others. Those who comprehend why it’s a smart—and crucial—step in the product development process set themselves apart from the competition.
The Relationship Between Prototyping and Product Design
Product development used to follow a linear path, with one phase beginning after its predecessor was complete. More often than not, it looked like this: design preparation; prototyping and testing; initial test production; and ramp-up and marketing introduction. The traditional product development process is fine in a market that’s fairly stable and predictable, but it’s ineffective in most of today’s dynamic marketplaces.
In the past, prototyping was viewed as a separate entity that most developers introduced after the initial design phase was complete. In reality, the two are not independent, and each step of the design process includes its own method of creating 3-D artifacts. A different view of how models and prototypes serve a more integrated process is to view it as serving essentially four functions that are intertwined with the various disciplines. Models and prototypes are used for creativity, communications, evaluation and—for the FDA—verification. To further understand the relationship between prototyping and product design, it’s best to look at how these fit within the steps of the design phases.
Design is more than creativity, but that’s where it starts. Good designers draw creativity from anything and everything. Both the designer walking through the aisles of a local Toys “R” Us or Home Depot looking for ideas—as is frequently done—and the designer in the shop working with “found” objects to simulate basic mechanical actions are tapping into new solutions based on parallels drawn from existing products.
For example, in one project with a client, the firm sought to miniaturize bar code scanners and adapt them to be worn on the forefinger by package handlers. The chassis and basic enclosure were straightforward, given conventional machined parts, stereolithography apparatuses and urethane castings. But the small plastic clips to hold the adjustable strap on the finger needed to be injection molded in production materials—and there wasn’t time for that. However, a walk through the local Wal-Mart led to the discovery of shoulder-strap clips on large-size women’s brassieres that were perfect for the project.
Sketching in 3-D
From a certain perspective, modeling is just sketching in 3-D. Just as some designers and engineers are most comfortable with a pencil or a seat of CAD, some are best when working in the shop. A sculptor doesn’t necessarily see the world the same way that a painter does. And it’s easy to jump into CAD too soon, which can lead to a sort of tunnel vision resulting in a “do it and fix it” process. Keeping things open to a variety of approaches using models and prototypes might be best, especially early on.
If a picture is worth a thousand words, then a model or prototype must be worth a million. For all of the creativity that comes from simple sketching, it’s always the first model that creates the big “ah ha” (or “oh, crap”) for both the design team and, importantly, for the extended team. Designers need to remember that other disciplines do not visualize objects represented in sketches—and even in 3-D CAD—in the same manner. There’s also the matter of “scale.” The breadbox-size medical products are pretty easy; model a defibrillator or patient monitor one-to-one, and what you see is what you get. But it’s usually time and cost effective to make a quarter- or half-scale model of a large clinical analyzer instead of a full-sized model. Even so, it’s always good practice to make at least a volumetric, full-sized model to get a sense of scale—and to address human factors issues in a simulated, dynamic setting. Or, at the other extreme, an engineer can get sucked into designing a plastic snap detail in a large CAD image that defies the properties of the materials when prototyped. At this point in the creative process, the models are the best way to preference test a variety of concepts with potential end users and, when the fidelity is high enough, to do preliminary usability testing—all good reasons to model early and model often.
As designs gel into a primary engineering solution, prototypes (both of physical objects and electronic user interfaces) take on the role of tools for evaluation. These may be mechanical/electronic, “shake and bake” or (as prescribed to be good practice by the FDA) be used for human factors usability testing in simulated environments of use. This is the critical crossroads for any project. No engineer wants to make major changes at this point in the process, and the management team that sponsors the work doesn’t want to hear about delays at this point either. But this is the lowest-risk and least-expensive time to take a hard look at the proposed solution and make sure that it meets the requirements of both the specification and intended use for the instrument or device. The physical models at this point are meant to supplement, but not to replace, other analytical tools such as mold flow and finite element analysis.
The typical crossover point from design and engineering to preproduction tooling and manufacture is in the final engineering phase and verification. Here, prototypes are used to verify that the design inputs match the intended product outputs. It could be as simple as checking tolerances and fits, but more often it allows the designers and engineers to ensure that the product performance meets the specifications. With the availability of prototyping materials that approach production performance, the verification process can assure that final mechanical, thermal, electrical, flammability and other performance requirements will be met as early in the development process as possible. By testing, documenting and correlating the prototype performance to production materials and processes, designers can deliver robust data to support regulatory submissions.
For the developers, there are even more options for prototype resources. Many prototype shops are expanding into low-volume production, and more production manufacturers are offering to help at the prototype end to get their foot in the door early. The most important rule of thumb is, don’t go with the low bidders. Saving a couple of bucks on a rapid prototype is being a pound foolish when there are tens or hundreds of thousands of dollars of engineering effort riding on the outcomes.
Models and prototypes are a way to test ideas. Ideas lead to innovation that helps to add top-line growth for customers and help designers to keep from being ”commoditized” as service providers. The contract manufacturers that can connect the dots between design/engineering and prototyping/production are most likely to gain a leg up on the competition. Couple that understanding with the familiarity of “model early, model often,” and there’s a key ingredient for a successful, proven and thriving business practice.
Jack Harkins, president of Farm Design, Inc., co-founded the firm in 1982. He is responsible for Farm’s business strategy and is an integral part of the business development team, where he focuses his expertise in cardiology and vascular markets. Jack’s true specialties and commitment are in discovering user needs using a wide variety of research methods to determine product specifications. He has led client programs for biomedical start-ups as well as industry leaders such as Schick, Johnson & Johnson and GE Medical. He has recently held positions on the board of advisors of The Design Management Institute and as chair of the Medical Section of the Industrial Designers Society of America. Jack graduated with honors from the Rhode Island School of Design with a BFA and BID in 1976. Farm is a full-service, FDA- and ISO-compliant product development company with more than 30 years of success in delivering product strategy, technology and development for the medical, laboratory and consumer industries.