中国国际医疗器械设计与制造技术展览会(Medtec China)2021

Dedicated to design & manufacturing for medical device

August 31-September 2 2022 | SWEECC H1&H2

Tighter Tolerances Prompting New Micromolding Innovations

2022-02-09

Timing truly is central to business success.

Microsoft, for example, could very well have been the world’s first trillion-dollar company had the public warmed to its tablet at the millennium’s dawning. Similarly, the world was not quite ready to embrace the future when Bell Labs unveiled its Picturephone in 1964 (imagine how different life would be today had it become commonplace back then).

Surprisingly, biotechnology firm Vaxxas hasn’t encountered that same dead end despite its invention being a bit ahead of its own time. The privately-held company is developing needle-free vaccination technology originally hatched by the Australian Institute of Bioengineering & Nanotechnology at The University of Queensland.

The technology uses a proprietary high-density micro-projection array patch (HD-MAP) to streamline and improve vaccine delivery. The postage stamp-sized silicon patch contains tens of thousands of projections 200-300 microns in length that release vaccine antigens directly to immune cells sitting just below the skin’s surface.

Preclinical studies have shown the Nanopatch to be considerably more effective than conventional vaccine delivery systems, with as little as 1/100th of its dose eliciting the same immune response as a “full” portion through intramuscular injection. Moreover, Nanopatch’s dry-coating technology eliminates the need for vaccine refrigeration during storage and transportation, thereby eliminating the resource burden of maintaining a cold chain.

“Based on our results, we believe that Vaxxas’ HD-MAP could offer a compelling solution that importantly could use less vaccine and potentially could be readily distributed without refrigeration for self-administration,” David A. Muller, Advance Queensland Industry Research Fellow, School of Chemistry and Molecular Biosciences, The University of Queensland, said last June. “This combination could make the HD-MAP extremely well suited to support the massive need for global population vaccination and indeed, we believe that HD-MAP offers a superior alternative to conventional needle-and-syringe.”

That superiority lies in the microscopic projections responsible for delivering vaccines. Those projections likely were created through micromolding, a highly specialized manufacturing process that produces extremely small, high-precision thermoplastic components with micron tolerances. This technique has become integral to medical device manufacturing of late as devices continue to shrink in size and scale.

MPO’s feature “Big Shots” details the trends and market forces driving micromolding in the medical device industry. Maggie Beauregard, quality manager; Sherry Bekier, account manager; Jared Cicio, molding/production manager; Patrick Haney, R&D engineer; Gary Hulecki, executive vice president; Kyle Kolb, tooling supervisor; and Lindsay Mann, sales/marketing director at MTD Micro Molding, were among the more than one dozen experts interviewed for the feature. Their full input is provided in the following Q&A:

Michael Barbella: What are the latest trends in micromolding technology and services?
Patrick Haney: The medical industry recognizes that devices and components can and should be miniaturized. As a result, we are seeing a higher increase in clients that are interested in converting a device that was previously manufactured using a different method and/or and completely different non-polymeric material. As the micro medical device industry continues to grow, medical OEMs are beginning to realize the potential and capabilities of micro injection molding and their engineering and design teams are testing the boundaries on things like overall size, pharmaceutical incorporation, overmolding capabilities, mechanical ability, etc.
Lindsay Mann: Customers need single-source suppliers. They need a partner that can service DFM all the way through custom assembly and packaging for any particular part design. As OEMs continue to prioritize consolidating their supplier lists, they are tasked to ensure the list contains specialty molders for their most complex/small designs that can support their immediate needs as well as their high-volume production.
Gary Hulecki: Utilization of robots, advanced vision systems, and software allows contract manufactures to save time and cost, while providing customers with accurate, complex assemblies or packaging solutions.

Barbella: What are customers demanding or expecting of their micromolded products and have these demands/expectations changed in recent years?
ared Cicio: There is a consistent increase in demand for more smaller dimensions and flash tolerances on molded parts. These have always been important features for any micro molded part, but tighter tolerances are requiring us to continue to explore and create new methods and procedures for machining our molds, molding our parts, and even how we fixture, inspect, and measure parts. A few years ago, we would typically see flash tolerances around .004”-.005” on drawings. We now typically see .002”-.003 maximum. This forces us to look at mold construction and molding parameters differently because our tools need to be built “tighter” to create parts that are “model-like” in quality. CT scanning of parts to check for internal features or voids is becoming more of the norm as well, which is a service we offer in-house to get real-time data and feedback.
Sherry Bekier: The demands witnessed over the past few years include the need for cost reduction plans, faster lead times, and more value-add activities. Also, the pandemic has caused the medical device field to be more careful with funding/budgets and having to deal with unexpected price increases and shortages of materials is a challenge for all parties involved. To remain competitive, value-added solutions are key. This includes assembly work, final packaging, and managing the outsourcing of other services for our customers. This all results in an easier, more cost-effective, single-source solution for manufacturing our customer’s micro medical devices.

Barbella: How have advances in materials impacted micromolding technology?
Haney: Material research is still one of the most prominent tools when it comes to improving micro processes. At the micro level, the flow characteristics of a material behave (in some cases) in entirely different ways when compared to “regular” non-Newtonian fluid behavior. These phenomena can lead to second and third order effects that influence things like crystallinity or defect formation. As the micro industry grows and learns, identifying and studying these trends allows us to apply pattern recognition to material science. We can now anticipate previously mysterious phenomena and avoid tedious time sinks and expensive troubleshooting activities by using this growing database of micro polymer behavior.

Barbella: Please discuss the challenges and complexities involved in micromolding tooling design. How can these challenges be overcome?
Kyle Kolb: Size and space constraints are usually the biggest challenges. These affect everything from gating, ejection, seal-off angles, to draft. The best way to work through these challenges is to complete a very thorough DFM process, almost always creating a solid model tooling split that will very closely reflect what you would want to see in steel.

Barbella: Design for Manufacturability is critically important in micromolding. How is this different than conventional DfM?
Kolb: DFM for micromolding becomes more critical due to gating, ejection, seal off angles, etc. These important details need to be vetted out very early on in the process. In macro molding, this is less critical as there may be many options for each of these features, but with micromolding we’re very limited. For example, there may be only one possible location for the gate, whereas a macro tool may have three to four possibilities. The same applies to ejection and other features. How well you navigate the DFM process will drive how easy or difficult the tool design phase can be. During the DFM process, getting the challenges on the table, whether it is radii vs. sharp, draft vs. no draft, or ejector/parting line/gate locations, will dictate how we go about designing the tool. We may have already dreamed up how the design will go, assuming some concessions can be made, but what if the parting line we thought of passes through a critical surface? We have to be able to adapt the tool design to ensure the client receives molded parts that function per their product design intent. Another thing we must keep in mind is wall aspect ratios as they relate to material selection. Can the material be changed to achieve the geometry or does the geometry have to be changed based upon the material? For example, we cannot mold PEEK as long and thin as we can Polypropylene.

Barbella: Are machine learning and AI playing a role in medical device micromolding? If so, how?
Hulecki: AI can be used in robotics to help with minimizing movements and make corrections on its own to increase throughput and prevent downtime.
Haney: From my perspective, the current use of AI systems in micro injection molding is more of a concept rather than a practicality. From a vision system standpoint, automated and speedy inspection can be much more of a challenge compared to our macro molding counterparts. Even though quick automated vision checks can be done “press side,” the small and intricate details of the typical part inspection often require much more robust inspection (i.e., CT scanning) that would be challenging to implement in the molding cell. Additionally, the use of AI systems to analyze injection molding processing parameters would be quite challenging. This is not to say that it could not be possible, however the fluid dynamics, phase transition behavior, and solid mechanical behavior of an injection-molded polymer is always extremely unique to a specific type and grade of material. The task of AI systems being implemented to identify behavior trends within pressurized polymeric fluid flow seems to be a relatively unexplored topic. However, the idea is a very exciting one.

Barbella: Is there a limit to how small a micromolded part can be? Please explain.
Haney: I believe there is no theoretical limit to how small a molded part can be. However, there is a practical limit that is driven by the manufacturing equipment’s ability to avoid material degradation, induce manageable stresses, and incite flow into a mold cavity with repeatability. This limit can change drastically given the complexity of the part geometry, application of the device, and the type of polymer material. This limit of a materials capability can be further pushed if the manufacturer understands and controls the characteristics of certain plastics phenomena such as shear imbalance, shear thinning effects, and crystallization. This is why the field of studying micro injection molding scientifically is so important.

Barbella: What medtech speciality (cardiology, wearables, orthopedics, etc.) presents the greatest challenge in producing micromolded parts and why? Which present the greatest opportunity?
Hulecki: Overmolding of microscopic Implanted neuromodulation devices. These tiny, high-aspect ratio electrodes typically have very sensitive electronics and delicate leads, which presents a challenge to “gently” overmold without damaging the important features of the device. Mann: Diabetes care applications like novel insulin infusion sets require the smallest, thin-walled cannulas available. Micromolding offers unique solutions for these applications with advanced molding equipment enabling ultra-thin walls, high aspect ratio features, as well as providing options to mold a cannula with a hub or other component as a single molded piece, eliminating the need for gluing or assembly and improving quality and function overall. These applications are a notable challenge for micromolding but with specialized equipment and unconventional tool-building methods, we are able to be a strategic partner for these types of parts.

Barbella: What regulatory requirements/changes have impacted medtech micromolding and how?
Maggie Beauregard: The European Union’s Medical Device Regulation officially went into effect in May 2021. These new regulatory requirements will continue to change the medical device world for those both located in the European Union and also those wishing to market their devices there. With new requirements covering almost all aspects of device regulations from lifecycle traceability requirements, updated post-market surveillance reporting requirements, new labeling requirements for Class III and Implantable devices, and even changes to how devices are classified, device manufacturers will need to pay close attention to these changes.

Barbella: How might the medtech micromolding industry evolve over the next five years?
Hulecki: We will see new lighter, stronger, reinforced polymers available for medical devices. This can replace metal implants as a more cost-effective and repeatable solution.
Mann: The micro injection molding market continues to grow, estimated to be about a $1.5 billion market within five years. Converting delivery and testing methods once done in a doctor’s office to ones that can be done at home require novel designs of existing and improving technologies to make these procedures simple, repeatable, painless, and reliable. Complex, smaller plastic devices that include overmolded sensors/delicate substrates are generally needed for these devices and require advanced micro injection molding to create. As digitization of miniaturized devices continues, we will continue molding around/over/through batteries, PCBs, and delicate substrates that perform important data transmission jobs. This will apply to many markets and applications.Protecting these substrates is crucial and encapsulating them with micro overmolding is an effective and feasible solution.
Cicio: It’s difficult to predict how the industry may evolve over the next five years but it is safe to say that customers are going to continue to expect tighter and tighter tolerances which will continue to push manufacturers like MTD to stay on the cutting edge of technology for toolmaking and molding methods. Today, customers are prioritizing contract manufacturers that can be full-service suppliers and we will continue to see more customers seeking this service where they can look to us to be their one-stop-shop to take them from molding all the way to final packaging.

Article source: Medical Product Sourcing