Design for Manufacturability (DFM) and Design for Assembly (DFA) are well-known methodologies and two design practices within a larger philosophy sometimes referred to as Design for Excellence (DFX). DFX aims to optimize a product's design for ease of commercialization. These approaches have been used for a long time in the development of consumer products to reduce costs and increase margins and are now increasingly applied in the medical device industry.
Our industry is under huge pressure and has incentives to file FDA 510(k) or PMA submissions to gain approval for market entry. Startup companies literally live and die by meeting these short-term milestones because they are often attached to funding rounds.
From startups to even the most experienced, established OEMs, if the race to meet short-term milestones is run blindly, they can forever hamstring a timeline, limiting production capacity and lessening the impact the device will have on patient lives. In this industry, like no other, leadership in design principles should guide development teams and incorporate up-front design planning to ensure a streamlined, predictable, repeatable production process.
The Manufacturer's Perspective
Medical device manufacturers can be strategic DFX champions to invite onto the design team. If they have experience across multiple devices and technologies, they've been on the front lines when development and production come to a halt due to a poorly thought-out design decision.
Pre-planning the production on-ramp and process startup is critical to limit later iterations that cost time and money. During the manufacturing process development phase, our responsibility is to limit those risks and devise a manufacturing strategy that can be scaled as the device enters the market. Manufacturers responsible for "baking the cake" have good recommendations when the recipe is written.
DFX Leadership Is Important
Depending on where you are positioned within an organization, you can impact the degree to which a particular design program effectively implements the tenets of DFX. A cross-functional team of disciplines is less effective if only one or a few members are DFX practitioners. Commitment to DFX practices leads to creating DFX ambassadors, especially once the ROIs begin to be realized.
In fact, when you consider the impact of DFX on other OEM stakeholders—investors, for example, who have the goal of realizing financial ROI as quickly as possible—you can understand how DFX practice can quickly turn into a philosophy, or even a culture, by which a company can increase its success.
Begin with the End in Mind
When a medical device development timeline allocates a very short time to concept and design, it can lead to longer periods of fixes and engineering change orders during early builds. This further delays the ramp-up time to stable production. Because of the regulations inherent in medical manufacturing, device changes become extremely difficult to implement as the program matures.
To be most effective, the entire development team should be aligned, motivated, and facilitated to use the DFX discipline to its fullest extent.
By intentionally expanding the conceptual phase of the development timeline, with a disciplined mindset and adherence to the tenets of DFX, companies can get a jump start on product commercialization, hurdling over much of the firefighting and change orders inherent in first-article builds, pilot runs, and process validations (see Figure 2).
Figure 2: Comparison of a typical medical device timeline and concurrent engineering timeline.
By the (Part) Numbers
Development teams need to measure the viability of a particular design approach early and often to determine whether they are on the best path toward production or need to change direction. This is best done by using a set of metrics to gauge one design approach against another.
The single most important metric to evaluate a product design is also the simplest one: part count. While it is easy to understand how a device with 100 parts would be more complex to manufacture than a device with 10, what may be underappreciated is how the natural sources of manufacturing variation multiply geometrically over those parts. It is not just the 100 parts you need to plan for; it is the two or five critical specifications of each of those parts, multiplied by all parts, which can become untenable. These variations are not always seen in short-run design validation builds unless intentional limit challenge builds are conducted.
The total number of parts in a device design has a more significant systemic effect on the entire business. Fewer parts to a design mean fewer parts to procure, receive, inspect, inventory, and conduct quality operations. Further, there are fewer opportunities for those parts to fail to conform to specifications and fewer risks for people and process to damage or install incorrectly.
Another metric by which designs can be measured for manufacturability is the number of processes — not only how many processes are required but whether there are special processes that are hard to control or have long cycle times.
For example, liquid adhesives are notorious for being problematic in manufacturing systems. Dispensing the exact right amount of adhesive in the right place is only half the problem. Waiting for an epoxy or adhesive to cure under the right conditions is the other half.
These setbacks can cause unnecessary troubleshooting and delays if not considered early in device design. Well-intentioned teams in a hurry to get a working prototype into a functional test to show results and meet tight timelines sometimes cannot resist reaching for a tube of glue to stick parts together. If that early design choice carries forward into production, it can present significant challenges to a manufacturing team responsible for validating the process. Further, when customer demand for the product increases (a good problem), scaling up an adhesive dispense-and-cure process, for example, adds more work to the process: clamping fixtures, space requirements to house the operation and maintain order, etc. These extra steps and accommodations are added chances for error and can quickly compound.
When DFX principles become part of the design stage, the design is simplified, which further simplifies the path forward.
DFX is a crucial medical device design philosophy that represents a set of techniques and, most importantly, a discipline that can help device OEMs get their products to market faster and help investors realize higher, faster ROI.
While the tools of DFX stand on their own, their true power is brought to bear when the entire design and development organization embraces the mindset and ruthlessly slashes design complexity — eliminating parts, adhesives, threaded fasteners, operator variation, and uniquely individual processes.
By implementing an early design evaluation process that encourages multiple iterations of concept architecture before starting detailed design and testing, companies can identify the most robust processes and design toward them to reduce costs and risks so that they can move forward to deliver products that treat patients.
A manufacturing partner who focuses on development and manufacturing, and thus has seen the best and worst cases of design that didn't pull the product all the way through its production process, has experience to share at the design stage. They could be the best guides for a lower-risk, higher-reward outcome for you and the patients waiting for your device.
Mick Fry is senior principal product engineer at Minnetronix Medical, which serves as a single-point provider for medical technology innovation and partners with medical device companies to accelerate breakthroughs in optical systems, fluid and gas management, RF energy, and stimulation and wearable devices.
