Laser Focused on Machining for Medical Device Manufacturing

Machining, micro machining, and laser processing are key manufacturing processes for the medical device industry. They continue to grow in popularity because they produce high-precision, small-profile components and sub-assemblies with remarkably tight tolerances, across an expanding array of advanced materials.

Not only are machining and laser technologies in high demand, they must also continue to innovate to keep pace with what medical device manufacturers (MDMs) expect to achieve with their new product designs.

“Few would have thought, a dozen years ago, that a sub-miniature assembly comprised of multiple components could be reduced to just one,” reflected Todd Dickson, president of Lumenous Device Technologies, a Santa Clara, Calif.-provider of precision components and assemblies for medical device companies, including nitinol semifinished materials production and component manufacturing. “Today we integrate our manufacturing processes to produce monolithic parts that do just that, with 20 µm (0.0008 inches) feature widths and locally tuned rounding or heat treatment using lasers, electrochemical machining, and ultraprecision electrical discharge machining [EDM].”

Micro machining and laser processing enable medical device engineers to design smaller parts with complex features and tighter tolerances that enhance device functionality, especially for minimally invasive procedures.

“CNC [computer numerical control] machining must maintain tight tolerances, robust production processes, and flawless finishes for these products,” said Damian Zyjeski, CNC product development manager for AVNA (formerly Okay Industries), a New Britain, Conn.-based provider of precision machining processes, including in-house tool design and build capabilities. “There is also increased need for multi-axis equipment with the ability to produce both large and small quantities of parts efficiently.”

Hybrid manufacturing equipment—which combines CNC machining, laser processing, and other manufacturing technologies into a single set-up—is often the most efficient solution for complex medical devices. “Lasers combined with CAD/CAM [computer-aided design/computer-aided manufacturing] and multi-axis machining have significantly enhanced the ability to process complex components for this industry,” said Tom Berg, president of Mountain Manufacturing Technologies, a Lino Lakes, Minn.-based provider of machining and fabricating capabilities for enhanced product development, prototyping, and production.

The laser/Swiss technology that AVNA uses is a hybrid process that combines turning and laser processing operations into a single process step, while providing higher accuracy and lower cost. “This allows us to provide fully custom and fully automated solutions for high-quantity jobs,” said Redi Nasto, laser technologies manager for AVNA.

As sophisticated as these technologies are, they must still advance to keep pace with medical device R&D, design innovation, miniaturization, and cost efficiencies. For example, MDMs and their contract manufacturers (CMs) continue to find new ways to use laser processing in the manufacture of their products. As MDMs learn more about what micro-machining and lasers can achieve, their engineers will design more devices specifically with laser processing in mind—especially drawing from the wide variety of available materials, ranging from sensitive biomaterials to hardened metal alloys.

Latest Machining Trends

Miniaturization and the highest precision are top goals for MDMs, especially for intricate components such as implants and surgical instruments. “Laser machining is gaining traction for its unparalleled precision in fabricating complex medical devices,” said Stephen Trinter, director of global sales and marketing for Pulse Technologies (recently acquired by Integer), a Quakertown, Pa.-based provider of custom machined components and assemblies for the medical device industry, now part of Integer Holdings, a global medical device outsource manufacturer. “For example, we are seeing an increased use of laser texturing to improve bond strength, especially on metal-to-plastic bonds. We are also using laser machining more often for small-hole drilling—beyond being able to achieve tight tolerances, laser machining can also provide extremely pristine burr-free holes.”

Automation of manufacturing equipment is a priority for MDMs and CMs. Automated processes also help with the shortage of workers and make the existing workforce more efficient by automating repetitive functions such as loading and unloading work, as well as some visual inspections. Machine controls are also getting smarter—“networking machines and integrating them with quality and business systems to keep the machines stable and efficient will continue to get easier,” said Zyjeski.

These advantages and efficiencies will lead to wider adoption of automation and robotics for “lights out” manufacturing—the ability to run highly automated production processes 24/7 with minimal human intervention, thereby improving efficiency and shortening time to market.

Sophisticated machining and laser equipment can also be used in creative ways to support individual therapies. “The ability to utilize CAD/CAM and multi-axis CNC equipment lasers to produce complex components in the structural heart disease segment, for example, has been significant and will continue to grow,” said Berg. “Utilizing nitinol, a thermal heat set formable material, has also been a significant reason the structural heart disease component has seen significant growth.”

As medical devices incorporate smaller and more intricate components, the need for micro-Swiss machining and 3D laser ablation has surged. To meet this increased demand, Resonetics, a Kettering, Ohio-based provider of advanced materials, product development, prototyping, and micro manufacturing for the medical device and life science markets, has developed its MICRABLATE technology, a 3D laser ablation process that transforms wire, tube, and sheet materials into micro-scale, precise components for delivery systems and implants. “We continue to develop complex five-axis CNC and micro-scale Swiss CNC machining for next-generation medical devices, particularly for neurovascular and ophthalmology sectors,” said Bob Baldino, director of strategic projects for Resonetics.

What MDMs Want

Top priorities for MDMs are quality, speed, and total engagement with their CMs through a design for manufacturability (DFM) team approach. MDMs seek partners that have quick turnaround knowledge about materials and manufacturing processes, as well as the ability to support production manufacturing, R&D, and quality control. Other key considerations are risk management, efficient operations utilizing the Internet of Things (IoT), and cost controls.

Increasingly, MDMs expect their CM partners to have the skills and experience to cut intricate parts from a variety of materials to create high-precision micron-sized features with tight tolerances. MDMs want to team up with vendors that have strong material expertise and the ability to access a variety of materials. “For example, precious metals like platinum and iridium are commonly used to manufacture electrodes for medical devices,” said Trinter. “Machining such materials requires expertise due to their unique composition, material properties, and high cost.”

Up-to-date processes include having the necessary metrology and inspection equipment to inspect tiny, complex features and surfaces. For example, automated coordinate measuring machines should be used to perform process inspections and produce first article reports. In addition, digital multimeters have the capability to take thousands of data points during a scan of a complex curved surface, which is ideal for complex geometries. Advances in inspection technology such as machine vision-enabled systems continue to ensure quality measurements can still be taken as features get smaller, with tighter tolerance requirements.

MDMs also seek out vertical integration—one source/location for manufacturing and materials expertise, DFM, and even the regulatory knowledge they need—basically a one-stop shop. “For laser processing, OEMs would prefer to work with a partner that can provide a suite of laser services, including machining, texturing, welding, and etching, all under one roof,” said Trinter.

Ultimately, “MDMs are looking for partners that can help them speed up time to market and improve overall component and sub-assembly manufacturability, quality, and cost,” said Nasto. “The best way to do this is through early engagement and DFM input from process and technology experts they can count on for quick-turn prototyping, robust quality systems, and proven operations that can meet production demands and on-time delivery.”

CNC Machining Versus Laser Processing

Micro machining and laser processing are techniques that are more complementary than competitive; deciding which one to use often depends on the specific medical device application. For example, CNC machining is commonly used for producing devices such as orthopedic implants, which are larger, structurally complex medical devices. Lasers, however, are preferred for processing thin-wall complex materials such as nitinol and other soft or hardened materials. “The biggest challenge with lasers is the secondary process to remove residual materials from the laser process,” said Berg. “The utilization of high RPM multi-axis machining has significantly enhanced the ability to process thin-wall and complex geometry components that require micro cutters and complex fixtures.”

In the realm of micro manufacturing, there exists a segment where both laser ablation and micro machining can fabricate identical products. While lasers provide precise ablation across almost all medical device materials, CNC machining traditionally excels with metals and, to some extent, polymers. “The choice between these technologies often hinges on several factors, including base material characteristics, surface roughness requirements, and economic considerations,” said Baldino. “Machining exclusively handles non-continuous inside diameters, whereas laser ablation is preferred for features like holes or slots finer than 0.05 mm. For items smaller than 0.2 mm in diameter, lasers generally offer tighter tolerances. Conversely, for bulk material removal in projects exceeding 0.5 mm in diameter, machining becomes more cost-efficient.”

“Pulse Technologies can perform high-precision cuts and features with very tight tolerances on various materials,” said Trinter. “Specifically, with our laser machining processes, we can offer a kerf-width of 40 microns. When it comes to processes like milling, we have the ability to hold tight tolerances and positions up to 0.0002 inch (0.005 millimeters). With EDM, we have the ability to manage tolerances and repeatability up to a 0.0001-inch standard.”

Laser machining is taking on a larger role in the production of intricate, small-scale components. Because lasers can create such high-precision features at the micron level, they are ideal for applications where miniaturization is critical (for example, ophthalmic devices, leadless pacemakers, and neurostimulation devices).

“Laser ablation can also process a wide spectrum of materials, ranging from human tissue to diamond, thereby enabling the use of non-standard materials in next-generation devices,” noted Baldino. “Additionally, lasers are adept at surface texturing any material, introducing functional properties such as enhanced cell adhesion or deterrence, and modifying surface characteristics to be hydrophobic or hydrophilic.”

Overall, the utilization of laser processing and laser technologies has substantially increased in the past few years, compared to standard CNC-type machining. “Substantial reductions in cycle times and cost can be achieved when specific features in parts can be processed via laser versus conventional turning and machining processes,” said Nastro. “We try to use lasers for all through-features. Also, with our hybrid machines, we can use machine tools and lasers on the same part, drastically reducing cycle time and providing a one-stop shop in completing complex parts in one process step.”

Expanded Design Possibilities

As medical devices become smaller, so do their components. Lasers can process many of these critical miniaturized components with high precision and very tight dimensional tolerances. Laser processing is a non-contact process and the kerf can get down to the sub one-thousands-of-an-inch range (about 20 microns), making it possible to process extremely small features while maintaining very high precision and accuracy. “At AVNA, we’ve processed tubing components as small as about 0.016 inches outside diameter and wall thicknesses as small as about 0.002 inches,” stated Nasto.

Lasers enable the creation of more complex features and geometries.

“If a feature can be revolved in SolidWorks or designed with ‘line of sight’ access to a laser processing head from above the material, it is likely manufacturable,” said Baldino. “Customers may not fully grasp the extensive capabilities of micro machining or laser ablation, perceiving them as niche processes. However, we welcome the opportunity to review any design or SolidWorks file and provide insightful DFM feedback.”

Resonetics’ Advanced Technology Group carries out R&D on new micro-manufacturing technologies, aimed to meet emerging market and customer demands. The team enjoys the challenge of pushing the technical boundaries for a variety of technologies, including advanced materials, product development, laser processing, metal fabrication, nitinol processing, sensors, microfluidics, and implantable batteries.

Pulse Technologies developed its proprietary Hierarchical Surface Restructuring technology, which enhances electrochemical performance for numerous medical applications in such areas as cardiac rhythm, neuromodulation, and cochlear implants. “In the end, this helps medical device companies improve component quality, performance, and importantly, reduce cost,” said Trinter.

Abundant Innovation

Following are just a few innovative machining and laser processing ideas, methods, and technologies for medical devices in use today.

Nitinol’s superelastic behavior depends on its transformation temperature (Af) to the superelastic phase. The Af must be carefully controlled, but reproducible. Af testing has been difficult to perform in the past. Lumenous Device Technologies developed its TruePhase technology to remove this uncertainty from device design and production. The non-contact machine vision system reduces sources of excessive noise, delivering instead clear data that is verifiable by a quick scan of the test in time-lapse. The system also permits measuring multiple test samples at one time in a variety of device architectures.

One of the biggest challenges of processing smaller and thinner materials is the heat treatment—especially the ability to control warping during the heat treating and machining process. Mountain Manufacturing Technologies has developed a proprietary fixturing process that contains its custom mandrels, “allowing us to hold the material straight during the heat treat and cooling process,” said Berg.

Technologies rooted by IoT—automation, robotics, artificial intelligence, data analytics, and in-line quality monitoring—are all on the rise and provide increased quality, productivity, process stability, and reduced downtime. Automation and robotics are making machining and laser processing more efficient, especially with intelligent machine controllers and systems. “With the advent of technologies like machine vision, we will see an increased use of automation and robotics on the factory floor,” said Trinter. “Machine vision can also help build smarter systems that can help with inspection of more complex devices.”

AVNA operates a custom laser marking system with five lasers that work concurrently, with automated feeder and hopper and an integrated robot for pick and place directly into passivation baskets. “This system provides the ability to laser mark and laser surface treat tubing components, while maintaining a high-quality process and maximizing product throughput,” said Nasto.

Laser surface restructuring, which can significantly improve electrochemical performance and device functionality, is an exciting area of development. “In a highly controlled and tunable fashion, electrochemical performance can improve multi-fold,” said Trinter. “Device robustness and longevity can be improved, and cost can also be reduced significantly through reducing electrode size or through an ability to use less expensive materials.”

Innovation at the Forefront

As medical devices get smaller, challenges will include machining more intricate features, maintaining tighter tolerances, and dealing with increasingly difficult quality/regulatory standards. Manufacturers must keep investing in advanced manufacturing and inspection technologies to meet these challenges. New cutting tools with better coatings, base materials, and geometries are always being introduced. Tools that offer improved durability, higher cutting speeds, and enhanced material removal rates will contribute to higher productivity and cost efficiency in machining processes, as well as faster time to market. Improved internal machine probing inspections will provide more detailed feedback to the CNC controller, which executes machine adjustments or provides feedback to stop the process.

Finding the right combination of machine tools is essential for efficient production of complex parts. “Often these parts will require a combination of turning, milling, and hole-making technologies in a single set-up,” said Zyjeski. “Swiss CNC machines can handle these parts. The newest models have plenty of live tool stations to produce the features. For small parts that do not require any turning or drilling, we produce them solely with live tooling.”

Miniaturization will continue to be a key factor in the evolution of medical device design. As parts get smaller, both handling and geometrical inspection become critically challenging. To address this, Resonetics Lightspeed Lab team has heavily invested in developing advanced geometrical inspection tools and material handling capabilities. “This allows us to reliably produce parts with features smaller than 0.05 mm and total dimensions of only a few hundred microns,” said Baldino.

More innovations are on the way, such as localized feature processing, burr-free machining via locally variable electrochemical removal, and surface-modulated laser cleaning. Other technologies coming to the forefront include micro-precision half-micron processing, surface stress-free machining, deep-hole processing, and processing of pre-coated surfaces, which frees engineers from trying to manage the shrinking effect in curing and drying when coating machined components.

“Localized feature processing sounds like science fiction, but it is the real deal,” said Dickson. “This process can tune features and material properties of a component at will. For example, laser-processing permits highly controllable effects such as radiusing certain areas of a part, locally specific heat treatment, surface texturing, outer diameter reduction, and more. Electrochemical machining and part post-processing like microabrasive blasting also enable localized features on the scale of thousands of an inch.”

Ultrafast laser technology and equipment can replicate turning and metal-removing applications on micro-scale components via the use of a laser and non-contact processing. Laser processing will continue to enjoy substantial growth as an essential technology in the manufacture of medical components and sub-assemblies. “The ability to stay at the forefront of technology, provide innovative solutions to customers, and maintain robust and high-quality standards, will be key for contract manufacturers to succeed and thrive,” said Nasto.

Also, as devices get more complex, so will regulatory and quality requirements.

“Sound technical expertise, a company culture of quality first, and compliance with necessary quality standards (FDA’s 21 CFR 820 and ISO 13485) are required when leveraging the above processes to build next-generation medical devices,” said Trinter. “With robust metrology and inspection equipment, manufacturers can adapt to these trends, accurately measuring ever tighter tolerances and intricate features.” 

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Mark Crawford is a full-time freelance business and marketing/communications writer based in Corrales, N.M. His clients range from startups to global manufacturing leaders. He has written for MPO and ODT magazines for more than 15 years and is the author of five books.