Rapid prototyping has long played a vital role in the evolution of medical device technology. Effectively applied during a product's early design stages, it can generate valuable feedback for the design team, reduce development time and costs, foster potential product enhancements and promote greater customer satisfaction.
Yet the practice of prototyping itself has had to adapt to new tools and methodologies in order to keep up with the rapid pace of innovation in the medical device industry. It has also had to navigate an evolving range of new manufacturing realities. Savvy medical device designers have learned to engage the production team and other stakeholders earlier in the product development process to leverage the traditional benefits of prototyping while also anticipating new manufacturing modalities. In short, rapid prototyping has met Design for X, or DFX, a methodology where the X represents not just excellence but any number of variables including testing, sourcing, manufacturing, repair, molding, reliability and automation, additive manufacturing, smart factory processes (Industry 4.0), and reliability.
Essentially, DFX adheres to traditional spiral development, which is a cyclical approach where end customers evaluate early results and engineers identify potential issues for resolution. However, DFX not only incorporates human factor studies in the engineering feedback loop, it also proactively probes how well a design will align with supply chains, test and production methods, and both traditional and emerging and evolving manufacturing technologies.
Design Stages and Early Prototyping
Successful product design relies on a stage gate structure, which organizes development into the three stages. The earlier that DFX and prototyping are integrated into this process, the better designers are able to determine whether initial assumptions are valid and where problem areas might crop up further on.
For example, medical device OEMs generally understand their product's end requirements, but they may not anticipate some of the intermediate development activities that must occur. There are often potential trade-offs to consider. A medical device that must be inexpensive to manufacture and reliable over a million hours of service probably has contradictory requirements. A product that requires near-total reliability but that does not account for testing costs is also problematic.
DFX practices approach product development from concept through end-of-life to isolate design priorities. For example, Design for Reliability (DFR), a subset of DFX vital for medical devices, is a systematic approach to incorporating reliability from prototyping through pre- and post-production. Customer metrics typically include acceptable risk, failure rate or mean time between failure (MTBF) during the warranty period, and product service life. To ensure effective design throughout the development process, a reliability management strategy should include these seven steps:
Develop a Design Failure Mode and Effect Analysis (DFMEA).
Obtain component-level failure rates.
Develop a theoretical reliability model.
Improve component design capability to meet reliability targets.
Perform component-level reliability testing to demonstrate design capability.
Develop a system-level reliability testing strategy.
Perform reliability growth testing to demonstrate reliability targets.
Prototyping at earlier stage gates can validate DFX concepts more quickly and also allow simultaneous exploration of multiple design concepts.
The emergence of additive manufacturing, or 3D printing, has been instrumental in this regard by eliminating the need to buy or wait for tooling before developing a prototype. In many cases, prototypes or even production-quality parts can be created without molds, and inspected visually or held in the hand to support Design for Assembly (DFA) efforts. Designers can see and feel how parts fit together — and without long wait times. They can also share prototypes with the production site and the end customer. Advances in 3D printing further allow multiple prototype efforts to make iterative progress through near instantaneous feedback.
Additive manufacturing also allows manufacturers to quickly tailor their medical devices or instruments for the exact patient who will use the product, which is particularly useful in surgical and orthopedic applications.
Enlisting Production and Supply Chain Contacts
As medical devices become more cost sensitive as well as increasingly complex through miniaturization and automation, it is imperative to involve the supply chain earlier than ever before in the design process in order to leverage commercially available off-the-shelf components whenever possible. This early involvement helps decrease product costs by avoiding the expense to design customized components as well as the reciprocal costs to manufacture them in small batches. It also potentially avoids the need to develop higher level assembly processes to integrate them in the final product.
Further cost advantages are possible by purchasing from preferred suppliers, by multi-sourcing components, and through leveraging component regionalization.
Importantly, enlisting the supply chain early in product development can also help shorten the design cycle and speed time to market. But there is a longer-view argument for this as well: As medical devices are expected to perform reliably over longer lifetimes, an important step in their early development is to identify supply chain vendors able to supply technologies that will support this agenda.
When a design is finished, its specifications are transferred from the design site to the production site. There are many ways to bridge this process. But one of the most effective ways is to involve the production team early in the design cycle. The feedback that the production site can provide about manufacturability isn't the only benefit of cross-functional collaboration.
In terms of both functional ownership and build locations, projects undergo important changes as they move from design to production. Typically, the last engineering development unit is completed at the design site. The production site then builds the first design verification unit. This change in location corresponds to a change in responsibility. When ownership passes from the project manager for design to the manager for new product introduction (NPI), more than just the project lead changes.
Each manager reports to a different organizational structure and is responsible for different metrics. Arguably, the most important difference is the behavioral framework. NPI project managers require standardization and repeatability to handle many new products, product refreshes, and aggressive monthly output requirements. Design project managers tend to be more focused on product quality and optimization. Therefore, the design site may not assign equal importance to standardization and outputs.
To ensure a smooth transfer of ownership, the design and production teams can leverage design reviews, gate reviews, and the overall involvement of the manufacturing site in the early-stage design process. Inputs for the NPI team include the bill of materials (BOM), quality requirements, assembly drawings, and component specifications. In-house design sites typically generate this data from the same applications that are used by the production site. Third-party design houses or the end customer's own in-house design group may use different tools, but this can complicate collaboration.
Bridging the Gap
Many things can hamper a product's seamless transition from verification to validation, and many are associated with the different mindsets that distinguish the engineering or R&D world from the manufacturing world. Engineering seeks downstream solutions, while manufacturing seeks solutions upstream. The root cause of these disconnects arises from variations in systems, procedures, metrics and capabilities between these two worlds, and they become amplified as time becomes a factor during the later stages of the project life cycle.
Involving supply chain and production teams early in the design prototyping process can help bridge this gap. It also allows greater opportunities for DFX methodologies to optimize a product design for variables such as testing, manufacturing, repairs and reliability.
Effective project management plays an important role here. Comprehensive project plans help to define stakeholder expectations clearly and completely. Statements of work contain contract baselines with specific deliverables and milestones. Continuous communications between the design and production teams, feedback from the end customer, and the results of human factors studies can all optimize prototyping's ability to reduce costs and accelerate time to market.
Prototyping has always been critical to new product development for the medical device industry. Today, it must also increasingly anticipate new market realities, adapt to evolving manufacturing methods, and involve all stakeholders earlier in the process in order to keep up with the increasingly rapid pace of disruptive innovation that is becoming the order of the day. OEMs that implement these practices will be in a much better position to turn challenges into opportunities, and become more competitive players in this fast-changing market.
This article was written by Cory Forbes, Vice President and Chief Technology Officer for Nypro, a Jabil company, Clinton, MA. For more information, visit here.