Save Time & Money by Implementing GD&T in Your Medical Product Design
No matter how precise the manufacturing process, there will inevitably be some degree of variation in the components that make up your medical product. All the parts that comprise the finished device will be minutely different from one another and from the spec. Even the most meticulous engineering drawings and detailed notes from the product design team can’t prevent these variations.
Medical devices feature complex curvilinear, ergonomic shapes that are more challenging to make than square parts. The way engineers have traditionally made process drawings, defined dimensions and tolerances, and measured parts in manufacturing verification tests — called coordinate dimensioning — is better suited to simple shapes.
Building Tolerances into Medical Product Design
The engineering process allows for some variation, or tolerance, between manufactured parts. In coordinate dimensioning, defining those tolerances and measuring them in complex finished parts and products is difficult.
Medical device designers and engineers are beginning to borrow an advanced way of working from aerospace and other industries where, like the medical industry, safety is a top concern. Geometric dimensioning and tolerancing (GD&T) takes a 3D view of components rather than the traditional X-Y coordinate view. GD&T is a more accurate way of defining tolerances and allows more efficient manufacturing without necessarily tightening the tolerances.
Ultimately GD&T represents a clearer way of thinking and visualizing parts and their mates. For a simple example, consider how rectangular coordinate dimensioning and tolerancing typically locates holes by their centers. But the center of a hole doesn’t touch or interfere with its mating part. It’s the surface of the hole that touches the mating part. In this case, GD&T would specifically focus on locating the surface of the hole directly. 
With GD&T, designers locate and tolerance surfaces and features precisely where they must be without increasing the tolerance.
If you’re struggling to follow along, I recommend taking an online, self-paced course. There are a few great ones, including the “Fundamentals of GD&T,” offered by SAE.org.
Why Medical Product Companies Should Implement GD&T
Even with all the benefits of GD&T, there is still reluctance and much misunderstanding.
Cost Savings
Again purpose of GD&T is to provide clarity, not tighter tolerances.
In fact, the tolerance area can be larger than with traditional rectangular dimensioning and tolerancing. GD&T more accurately communicates the product design to the manufacturer. It allows designers and engineers to be very specific in what they demand of manufacturing, but at the same time allows freedom for the manufacturer to use their expertise to do things the best way.
The only higher cost is in training your design and engineering team; everything else is less expensive down the road.
Better Communication
The good communicators typically have large vocabularies which allows them to convey an idea accurately and concisely. In our engineering world GD&T provided the language to communicate accurately and concisely without lengthy notes on how to measure, reference features, a surface’s tolerance, etc. All the how-to’s are inherent in the GD&T language which eliminates the time-consuming, back-and-forth communication between manufacturer and designer.
With GD&T, the design intent is baked into the tolerancing choices and the measuring methodology, so the designer’s instructions and expectations of how the finished part is supposed to look and perform are clear to the manufacturer.
Protection of IP
Outside of a company’s employees, its most valuable asset is intellectual property. The accuracy of the GD&T methodology captures your innovation in a clear, concrete, and defensible way. It ensures that your foundational ideas are recorded precisely.
Improved Consistency
Whether you’re making one part or one medical device per second, GD&T provides complete, unambiguous, 3D definition of part geometry to maximize tolerance while still guaranteeing function. Designers and engineers can better define feature locations and profiles without tighter specifications.
Implementing GD&T in Your Company
Many manufacturers across industries already understand GD&T. And those that don’t are fading away. Internationally, across cultural and language borders, GD&T eliminates the hand waving and sketching to clarify a component’s intent.
Implementing GD&T into your process will require training your design and manufacturing teams. Depending on the training method, the up-front cost for a team of less than 10 people will range between $1,000 to $8,000. We recommend a combination of online and in-person training.
The benefit of hiring an in-person instruction for your organization is that the instructor can focus on your needs specifically. And later, as you start to implement GD&T, your instructor can be your coach. Having a coach greatly speeds up the learning process.
At MPE (Formerly Mindflow Design) , our designers and engineers have become fluent in GD&T, and it’s now an essential part of our workflow. If you’re considering making the move, we’re happy to share what we’ve learned.
