Micromolded plastic has function, miniaturization and automation advantages over machined metal for surgical robotics components and instruments.
By Martin Johnson, Viant Medical
Micromolding will play a central role for increasingly complex medical devices such as surgical robotics systems. [Photo courtesy of Viant]
Micromolding offers promising new ways for medtech companies to deliver innovative products that save more lives while reducing the cost of implementation. While injection molding isn’t new, recent breakthroughs are expanding what injection molding can achieve in medical device manufacturing.
One area where micromolding offers groundbreaking possibilities is advanced robotic-assisted surgery (RAS) systems. Until the 1980s, manufacturers relied primarily on metal for most surgical devices. Metal is biocompatible, sterilizable, durable and easy to machine into the geometries needed for devices of the time.
But as device complexity increased, metal components became much more expensive to produce. Production was time-consuming and often generated large amounts of scrap, which raised manufacturing costs and product prices.
Initial medtech applications of injection molding
Increased manufacturing efficiency is playing a large role in the shift from micromachined to micromolded components for robotic-assisted surgery devices. [Photo courtesy of Viant]
Although invented decades earlier, injection molding of plastic components became a viable, large-scale commercial option in the 1970s. Engineers recognized its ability to produce increasingly complex components. Instead of spending minutes to machine a single metal part, large multicavity molds could produce dozens in a matter of seconds.
Injection molding also improved part quality, offered process repeatability, and allowed for tight tolerances while drastically reducing material waste and scrap cost. By the 1980s, medical device manufacturers had widely adopted injection molding for its clear performance and cost advantages.
High performance polymers lead to a breakthrough
High performance plastics like polyetheretherketone (PEEK) have material characteristics superior to metal, such as strength, lubricity and radiolucency. [Image courtesy of Viant]
At the same time, material engineers began focusing on high-performance polymers. Up to that point, the largest barrier for adopting injection molding was the lack of polymers suitable for medical use. Biocompatibility was essential, and at the time, metal outperformed polymers.
That changed when high-performance polymers like polyetheretherketone (PEEK), liquid crystal polymer (LCP), polyethersulfone (PES) and polyphenylene sulfide (PPS) entered commercial use. These polymers offered better lubricity, can be sterilized like metal, and in some cases were more biocompatible than the metals used in medical devices of that era.
As injection molding scaled commercially, engineers began to see some of the limits of molded components. Larger, simple components transitioned easily to injection molding, but smaller intricate parts still required traditional metal fabrication. As a result, micromolding technology became a key area of development focus. At the same time, high-performance polymers reached cost parity — and in some cases, even fell below biocompatible metal options.
Micromolding replaces metal in most RAS systems
Micromolded plastic has function, miniaturization and automation advantages over machined metal for surgical robotics instruments and parts such as gears. [Image courtesy of Viant]
Today, micromolding plays a critical role in manufacturing RAS systems because of the ability to achieve complex geometries, lower manufacturing costs, and improve overall device functionality. Micromolding has made lifesaving, minimally invasive care significantly more accessible and affordable.
Simultaneously, integrated metal parts for RAS systems have stagnated. While metal parts can be fabricated at a micro level, creating complex geometries with traditional metal fabrication techniques can introduce challenges that micromolding avoids.
For example, RAS systems use multi-degree-of-freedom joints with internal channels for high-flex cables, irrigation and suction, and sensor integration. Machining metal into such small, curved internal channels is extremely difficult, especially at scale, and the cost of producing these metal components is a significant problem for most commercial manufacturers.
Why RAS systems are moving toward micromolded plastics
Specialized molding processes like two-shot molding and in-mold labeling are crucial to vital functional and aesthetic elements of robotic-assisted surgery devices. [Image courtesy of Viant]
Micromolding reduces manufacturing costs by improving material efficiency and production speed. It also shortens cycle times, and in most cases costs less than their metal counterparts, a reversal from when micromolding first emerged.
Improved device functionality is another reason RAS systems are shifting to high performance plastics. During calibration of these systems, engineers depend on each part to meet tight specifications. Metal components can have slight deviations, often requiring device-by-device calibration to ensure smooth operation. Micromolding produces components that match, leading to a more efficient calibration process. Specialized additives like barium or carbon can enhance functionality, improving radiopacity during RAS operations.
The present and future of micromolding
Micromolded plastic components on a dime for scale [Photo courtesy of Viant]
Viant recently partnered with a customer to develop a micro-insert-molded component critical to end effector function. Metal wasn’t an option, as the part needed to provide electrical insulation.
Viant selected a high-performance plastic and developed a custom micromolding process to meet all performance requirements, including complex geometry and durability. The project required intensive engineering during development and resulted in an optimized solution that provided a validated, repeatable process that delivers complex, life-saving components for RAS devices at a lower cost than metal alternatives.
The shift from metal to micromolded, high-performance plastics is accelerating. Its use already extends beyond RAS and is helping to reshape the possibilities within the medical device industry.
As medical device complexity increases, so does the need for scalable, precision-engineered solutions. Micromolding will play a central role in meeting that growing demand, driving innovation across the next generation of medical technology.
Viant VP of Technical Solutions – Polymers Martin Johnson [Photo courtesy of Viant]
Martin Johnson is VP of technical solutions – polymers at Viant. Johnson has deep expertise in micromolding, a foundation in mold making, and decades of experience in scientific injection molding for the medical industry at leading contract manufacturers.
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The opinions expressed in this post are the author’s only and do not necessarily reflect those of Medical Design & Outsourcing or its employees.
