Inside a pacemaker, several microparts work in tandem to keep the heart beating. It has a highly miniaturised circuit with various micron-scale components to detect cardiac signals, deliver electrical impulses to the heart and manage the pacing. All of these are packed in a case that is as small, or even smaller, than a pill.
Likewise, many medical and surgical devices have hundreds or thousands of microparts, with sizes in the micron to sub-millimetre ranges. Moreover, with a trend towards miniaturisation of medical devices, multiple micro-scale technologies need to be fit into tiny casings. For example, wearable sensors combine microfluidic channels and microelectronics into increasingly thin and stretchable interfaces.
Miniaturisation, along with the development of minimally invasive surgeries and point-of-care diagnostics for an increasingly growing list of medical conditions, is pushing the demand for medical device microparts.
Meeting this demand isn’t feasible without automating the manufacture and assembly of microparts. Manual operations on parts smaller than a millimetre lead to inconsistent and inefficient production, and increase the contamination risk, thereby jeopardising the safety of the final device. To mitigate these challenges, medical device manufacturers are automating their assembly lines with high-speed, high-precision machines capable of handling microparts.
Micron-level precision
The clinical utility of microparts often relies not just on being made to certain sizes but also on precise dimensional specifications. Orthopaedic implants, for example, can fail to fit or work properly unless they’re made with the exact dimensions and surface finish. Manufacturing these implants requires precisely cutting and welding materials into complicated, and often patientspecific, geometries that are difficult or impractical for manual operators to replicate.
Replicating this level of fine engineering at scale to meet the growing demand for medical devices is a daunting challenge. In response, manufacturers are deploying high-speed, high-precision assembly machines that can dexterously manipulate microparts while operating at thousands of moves per minute.
These machines leverage a range of enabling manufacturing technologies. Take, for instance, fast and precise gantry stages that support the latest machining and 3D printing methods. These platforms support exceptional repeatability of operations with nanometre-level precision. Robotic laser systems achieve exact dimensions and tight tolerances while making cuts and welds. This allows the design and production of microparts with superior structural integrity while minimising material waste.
Machining medical microparts can be tricky because, in addition to the size constraints, they often require a very precise surface finish. For example, “surgical needles cannot have any kinds of small chips on the edges of their surfaces”, says Jay Lee, director of the Industrial AI Center at the University of Maryland.
With advances in 5-axis computer numerical control (CNC) machines, it’s now possible to achieve extremely precise control during machining to meet the most stringent surface finish requirements. Capable of simultaneously operating along three linear and two rotational axes, they can create features like internal cavities and intricate geometries unrealisable by human operators. 3D printing is enabling new medical part designs, too.
“With additive manufacturing improvements, you’re seeing the ability to translate very complex geometries that have been either impossible or challenging to reliably or cost-effectively machine,” says Dustin Vaughan, VP, R&D, robotics, at Asensus Surgical. As these designs make their way into the market and the clinic, Vaughan says, “there is a huge shift in the way people are designing medical devices”.
Modern CNC and additive manufacturing systems can also be heavily automated. Parallel advanced robotic systems can manipulate tiny parts with unparalleled accuracy. Putting together these developments allows medical device companies to execute a significant portion of the manufacturing process within fully automated cleanrooms.
This prevents contamination from lodging in tiny surfaces and grooves, typical in many medical devices, where they are harder to disinfect. The entire assembly can be performed without any human operators entering the cleanrooms, keeping the devices completely sterile.
Manufacturers can assemble syringes and noncritical surgical tools in Class 8 standard cleanrooms, and catheters and stents, among other medical devices, in ISO Class 7 standard cleanrooms. The sterile conditions are maintained after assembly as well. Robotic packaging systems, capable of operating within cleanrooms, can encase devices in protective packages without damaging them. Combined with automated sterilisation, this ensures medical parts meet the strictest hygiene standards as they leave the manufacturing facility.
Testing at speed
Testing is necessary to ensure that a device that’s produced quickly is also produced correctly. Manufacturers test a product at multiple steps during the manufacturing process, including when it’s finished. “Most manufacturers test far more than required from a regulatory perspective because it’s much more effective economically to catch these mistakes well before they make it to end-of-line testing,” says Vaughan. However, each test slows down the assembly process.
When the assembly is fast, testing becomes the ratelimiting step. “If you make it fast but test it slow, it doesn’t help you too much,” says Lee. To bridge this gap by coupling high-speed assembly with automated quality control, medical device companies are integrating AI-based inspections in their manufacturing operations. For example, robotic vision systems continuously scan products along the assembly line and can spot even micron-scale chips on needle surfaces.
Improvements in computer vision are essential drivers of faster integrated inline quality inspections. Combining ultrafast cameras with the latest AI algorithms, vision systems can precisely and accurately measure the shapes, dimensions and features of microparts. “We can place a pile of parts on the imaging bed, and the system will automatically identify the count and do dimensional checks,” says Vaughan. “Those tools are enormously faster than even your best operator could ever be and are very effective,” adds Vaughan.
A crucial way high-speed, high-precision machines speed up medical device testing is by reducing the number of assembly steps. “Manufacturers inspect a lot between steps, and that is going away with some of the improvements that we’re seeing,” says Vaughan. For example, previous machining or additive manufacturing technologies relied on designs that incorporated features to hold the part during the in-between steps. On the contrary, new 5-axis CNC machining and additive manufacturing methods eliminate the need to reorient the product. Vaughan says, “This enables creating the part as it’s intended, whereas historically, for fine geometries, that might require post-processing and polishing.”
Capturing detailed inspection data for each product enhances traceability in the manufacturing facility and across the supply chain. “High-speed, high-precision automation bundles three functions into one,” says Lee. “It’s high-speed, intelligent and traceable.” This allows manufacturers to quickly locate defective products or batches and identify root causes for recurring defects. It also improves regulatory compliance by generating auditable digital records. “Automated prediction and traceability with a root cause analysis can support continuous certification,” says Lee.
With highly precise assembly machines, any instances of poor product quality are typically due to their suboptimal operation. This underlies the challenge in balancing high speed with high precision, particularly for fast-moving medical products. Even a small scrap rate could amount to millions in lost materials annually. Manufacturers need to maintain product quality at volume while minimising assembly downtime. Thus, they need to catch any errors in the assembly process before the product reaches the end-of-line.
Inline data from automated machines helps with this, too. IoT-enabled connectivity between assembly machines provides real-time insights into factory floor productivity. This allows manufacturers to implement predictive maintenance of assembly machines, thereby preventing loss of time and revenue.
Scalable, high-speed production
The use of industrial IoT in high-speed, high-precision production allows manufacturers to predict any bottlenecks in the production process and avoid costly scenarios. Moreover, when complemented with analytics and AI, it can track and quantify material and equipment costs for each step. Consequently, manufacturing operations managers can figure out areas where they can increase efficiency and reduce costs. Medical device manufacturers can benefit from this by flexibly producing both high-volume, low-cost and low-volume, high-cost parts or different variants of a particular part or product.
Many medical device microparts come in varied sizes and specifications to serve different patient populations or for use in different medical devices. Parts like microcontacts or catheter tubes, for instance, can be made for different diameters, geometries and flexibility. Scalable automation platforms with instant changeovers allow medical device companies to manufacture different product variants in the same assembly line. These further speed up production and reduces machine downtime. Automation of assembly lines isn’t happening in a vacuum. In recent years, the medical device industry has adopted innovations to automate other aspects of manufacturing. “Things like warehouse control and inventory management would largely be automated,” says Vaughan. It’s already happening to some extent in the industry, but it could become much more ubiquitous. “It exists for very high-volume parts like electrical components, but you’ll see that deployed into lower-cost environments in the future,” adds Vaughan.
Real-time data from high-speed, high-precision assembly machines would be key to enabling these automations. But the benefits flow the other way too. Automated warehouse and inventory management could provide immediate, error-free access to the exact materials during assembly. Down the road, manufacturers will translate these benefits into more efficient and even more miniaturised pacemakers and other medical devices.
The role of 5-axis CNC machining
5-axis CNC machining is pivotal in the fabrication of complex medical devices, enabling the production of intricate geometries with high precision. This advanced manufacturing technique moves the cutting tool along five axes – three linear (X, Y, Z) and two rotational (A, B) – allowing for simultaneous multi-directional movements. Such capability is essential for creating components like orthopaedic implants, surgical instruments and microfluidic devices, which often require tight tolerances and complex shapes.
For instance, a study from the University of Connecticut demonstrated the conversion of a 3-axis milling machine into a 5-axis system, effectively producing an implantable flow sensor. This adaptation showcased the feasibility of utilising 5-axis machining for medical applications, highlighting its potential in enhancing manufacturing capabilities for the medical industry.
The integration of 5-axis CNC machining in medical device manufacturing not only improves the precision and complexity of components but also contributes to the advancement of personalised medicine and minimally invasive procedures.
Source: University of Connecticut
