Machining continues to be in high demand for orthopedic device manufacturing. With machinists in short supply, medical device manufacturers (MDMs) and contract manufacturers (CMs) are relying even more on automation, robots, and Internet of Things applications to make their operations as efficient, productive, and competitive as possible.

MDMs continue to design and develop complex, miniaturized parts and assemblies. This is especially true for minimally invasive (MI) implants, devices, and tools such as instrumentation, smart implants, in-home monitoring post-operative devices, and personalized implants. Smart implants in particular are being used in knee and hip arthroplasty, spinal fusion, and fracture applications.

“Smart implants are gaining prominence for their ability to detect infection, movement, fusion, and other potential complications that cannot be detected in situ without invasive testing,” said Alice Higdon, vice president of sales for Trimaster, a Guelph, Ontario, Canada-based provider of precision machining for implants, instrumentation, electromechanical assemblies, complex assemblies, and robotic components.

With increased complexity and functionality comes the need for processes that provide repeatable, precise, and accurate dimensional controls at very small scales. Manufacturers of computer numerical control (CNC) machines are meeting these high-precision needs by adding improved process controls and automation. Precise chemical and processing control of raw materials is also critical for reliable yield during production and repeatable machining performance. Hybrid equipment, quick-change tooling, and oscillation cutting also save time, which helps meet the never-ending pressure on CMs for faster production and speed to market.

Although technology advances are happening in machining, many positive production impacts can be generated by simply boosting proficiencies, such as “linear palletized systems, lights-out manufacturing, robotic-assisted manufacturing, streamlined programming, and set-up times,” said Higdon.

Increasingly, MDMs are incorporating robotic systems and high-resolution navigational controls into their medical devices. Robotic instruments are pushing the boundaries of both machining and inspection capabilities for this specialized equipment, especially greater positional control.

“Our investment in five-axis mills with palletization allows us to get to more of the features using one work-holding position,” said Brian Blackwell, strategic account manager for Viant, a Foxborough, Mass.-based global strategic manufacturing partner that helps medical device OEMs bring complex medical devices and components to market. “This increases part-to-part repeatability with less reliance on operator interaction. With this comes greater need for more robust and automated inspection systems, such as more programmable vision systems that allow for faster throughput, higher volume, and the ability to combine both vision and touch-probe systems within one measurement system.”

Machining CMs are staying busy as OEMs emerge from the COVID-19 pandemic, eager for fast production of multiple products that were shelved two years ago. This surge is also driven by people who are finally moving forward with elective surgeries. Many MDMs are bringing plenty of new, innovative designs to their CMs that need to be evaluated for manufacturability; customers are also demanding shorter lead times, adding more pressure for quick delivery.

“We have literally been slammed with business from most all of our legacy medical OEM customers, as well as numerous new and exciting opportunities,” said John MacDonald, president of AIP Precision Machining, a Daytona Beach, Fla.-based provider of mission-critical polymer and composite machining for medical device and aerospace companies. “Therefore, our critical challenge is to effectively communicate real expectations to customers, while not overstraining our people nor creating new avenues for mistakes.”

What OEMs Want

OEMs are always intent on finding new ways to increase quality, reduce lead times, and save money. Increasingly, they seek to streamline business operations by outsourcing manufacturing so they can focus more of their internal processes on development. Therefore, OEMs increasingly rely on CMs for their manufacturing know-how and problem-solving. Design activity is especially high among the foot and ankle sector for implants and polyetheretherketone (PEEK)-based surgical tools.

“They want help with design for manufacture,” said Blackwell. “We are finding more OEMs are relying on our expertise to come up with the most efficient and effective way to machine something. But they also want us to reduce unnecessary geometry on parts to save on cost. We’re seeing these types of requests come through with much greater frequency.”

CMs prefer to be involved as early as possible in design for manufacturability (DFM) studies so they can leverage their experience to help design the best possible product at competitive pricing with shorter lead times, even in the midst of wobbly supply chains.

“We’re getting involved with projects much farther upstream,” Blackwell added. “Customers are coming to us with concepts or napkin sketches as opposed to finished drawings. It’s a longer road for us to be involved, but it makes for a shorter, easier path to market.”

A key consideration during DFM is stack-up. As device assemblies become more complex, and multiple manufacturers are contracted to create individual pieces of an assembly, design intent becomes extremely important to manage tolerance stack-ups and ensure parts work together and assemble as designed. If the tolerance stack-up is wrong, or the process needs adjusting, time to market can be delayed. This is where CM input during DFM is so valuable—simplifying a device or streamlining the production process to reduce stack-up can turn an unmanufacturable design into a winner.

“Most engineers I’ve worked with from the OEMs are grateful for any product improvement efforts and ideas during conception,” said Steve Smith, product development engineer for Huron Tool, a Farmingdale, N.Y.-based orthopedic instrument manufacturer. “Even after the production release, product improvement engineers are happy to consider an engineering change order if it results in a cost or time savings.”

One of the biggest manufacturing challenges facing MDMs today is simply availability of materials and components. Material challenges have been a tough obstacle for MDMs and CMs during the pandemic and the changing geopolitical landscape. “We have seen lead times for raw material out as far as 12 to 18 months for some materials,” said Smith.

Being able to minimize supply chain delays and find the right materials in a reasonable amount of time, and still meet aggressive timelines goes a long way toward building trust between the OEM and the CM.

“Supply chain issues have greatly impacted the ability to procure raw material, especially in pre-cannulated bar stock, which is becoming higher in demand due to the trend in minimally invasive surgery,” said Higdon. “At Trimaster, we have implemented deep gun-drilling so that we can utilize solid bar stock, thus decreasing lead times on cannulated material.”

This type of creative, proactive effort to manage the supply chain is one of the most important attributes a CM can have for winning outsourcing work from OEMs.

“OEMs want dependability from a trusted partner, since they are dealing with the most challenging supply chain in modern history,” said MacDonald. “Past reliance on sourcing from China is providing a wake-up call to those sourcing managers and CEOs who went too deeply in that direction. U.S. manufacturing is in a complete battle for capable talent and at the same time trying to create new manufacturing talent to backfill the demand.”

Technology Advancements and Trends

Lasers continue to be used in creative ways, such as laser cutting, laser welding, laser texturing, and laser knurling. Laser micromachining can remove material in nearly any shape, creating features as small as 10-20 microns in diameter, with submicron tolerances. Ultrafast laser machining is especially useful for producing high-precision components with complex patterns. These lasers can also make small, high-resolution black marking for devices and instruments; anti-counterfeit laser marks can even be applied that can only be picked up by machine vision.

Ultrafast lasers can ablate many different materials with no heat-affected-zone, burr free. This cold ablation process also protects the base material from subsurface micro-cracking and reduction in fatigue strength—making it ideal for cutting stents and drilling catheter tips.

“Laser machining also proves to be very efficient in preventing fading, flaking, and degradation during multiple sterilizations,” said Higdon.

Femtosecond lasers are the fastest—with femtosecond (1 fs = 10-15 s) pulses of laser light that are extremely well focused, they can cut complex shapes with high dimensional accuracy. “Because of their superior peak power, femtosecond lasers can process nearly any type of solid material, including layered, mixed, laminated, or coated materials, with the highest quality and precision,” said Blake Winkelmann, technical solutions manager for Spectrum Plastics Group, an Alpharetta, Ga.-based provider of critical polymer-based components and devices for medical and other demanding markets.

Lasers can also be used for surface texturing, instead of media blasting prior to coating on titanium implants. Advantages include eliminating the need for masking, 100% digital controls, reproducible surface texture, and a cleaner process that may even eliminate the need for a post-cleaning stage.

“One of the greatest benefits of femtosecond lasers is the reliability/repeatability of the micromachining of complex features and patterns with great accuracy,” added Winkelmann. “In fact, some features can only be cut with femtosecond lasers, expanding design options for engineers and designers.”

Laser processing can also be combined with machining in hybrid equipment that eliminates steps and saves time. For example, by combining laser cutting and welding with traditional Swiss turning, laser-Swiss machines can perform multiple processes in a single setup, which streamlines the validation process. The trend toward hybrid equipment also drives costs down by shortening lead times for prototyping and production volumes. Swiss-turn machining and laser cutting can be combined for laser-cut slots and holes and simultaneous machining of differing outside diameters, which reduces set-up time, secondary processing, and handling costs.

The Internet of Things is getting plenty of attention in the machining world—especially the combination of sensor, automation, and robotics technologies to allow “lights-out manufacturing”—meaning no human operators are needed to run the equipment. Letting a system run unattended can seem nerve-wracking at first, but hundreds or thousands of sensors track all the key performance indicators in real time and can shut the system down if needed. All variances are reported immediately via text or email to the personnel in charge of the production cell. Whatever is out of spec can then be corrected quickly, minimizing downtime.

Viant is a company with lights-out capabilities. “Specifically,” said Blackwell, “palletized five-axis machining allows us to address the labor shortage, but also allows us to create modular fixturing, which enables us to run multiple products with very little changeover, on one machine. The result is that we can flex with customer demand in near real-time. We see forecast changes quite frequently from OEMs, and having that ability to change from size-to-size, or a completely different product if need be, with almost no set-up, using palletized machines, has been a real game-changer for us and our customers the last few years.”

Manufacturers are also interested in predictive maintenance. Sensors can measure certain vibrations, sounds, and other indicators to predict when a piece of equipment is going to break down. This gives the operator enough notice to perform maintenance and make repairs with minimal downtime. When artificial intelligence (AI) and machine learning are added to the setup, the software constantly analyzes and evaluates data, and can even make adjustments based on what it determines from the data.

Predictive maintenance will only get more popular as MDMs and CMs recognize how much better it can make its operations.

McKinsey reports predictive maintenance tools can reduce manufacturing machine downtime by 30-50% and increase machine life by 20-40%.1 Of course, this increases efficiency and productivity, reduces labor, and extends equipment life—all of which speed up production time and time to market.

As machining advances its capabilities, so must inspection. Coordinate measuring machines (CMM) are the most popular and can be standardized for inspections to ensure processes are stable and can reliably maintain tight tolerances. Quality, accuracy, and validation can also be measured with computerized tomography (CT), which measures part features so small they are difficult to see with the naked eye, or are hidden within the walls of molded parts. Voids, sink marks, and other common molding defects can be observed just by scanning the component and inspecting the results. CT machines are able to achieve accuracy to the millionth in inches, whereas most traditional CMMs are accurate to the nearest ten thousandth in inches.

Subtractive Versus Additive

The orthopedic device market is one of the fastest-growing industries for additive manufacturing (AM). AM is suitable for complex parts, internal features, and low-volume components; however, it is a slower process compared to CNC machining, as the various layers of material in AM require time to heat and solidify, making it too slow for large-scale production. AM also cannot produce the tight tolerances or low surface RA that CNC machines can achieve. In addition, machining has established known performance standards—these are still being developed for AM.

“Additive manufacturing allows us to get elaborate shapes and structures that cannot be achieved with a CNC machine,” said Blackwell. “However, it is a slower process unless you are doing it at a large scale. The other thing is the tolerancing. With additive manufacturing, it can be very difficult to achieve the tolerances that some customers need—for example, holding down within 0.0005 inches total tolerance.”

Another difference between AM and subtractive machining is often the resulting surface finish. A CNC-machined surface is typically much smoother compared to an AM surface.

“The majority of components that are 3D-printed require machined finishing, so in many instances, it makes more sense to machine the entire implant,” said Higdon. “Successes have been made with components that are under compression such as spinal cages and acetabular cups, but obtaining tensile strength for larger components is still proving to be a challenge. As software improves, these challenges should be improved as well. AM is very efficient for rapid prototyping, some customs and specials, and some instrumentation. The biggest challenge at this point is developing protocols that ensure there are no voids in the 3D structures, which is crucial in obtaining FDA approval.”

CNC machining and AM are, however, not mutually exclusive.

For example, CNC machining and AM can also complement each other. Machining is often needed as a secondary operation to finish an AM-made orthopedic product. Machine manufacturers are building hybrid, dual-purpose machines that incorporate both AM build-up and CNC tolerances, speeds, and surface finishes in both series and parallel operations. A semi-finished component is placed into the system that then performs both subtractive and additive manufacturing processes to produce the final device—leveraging the best portions of each process.

“While additive manufacturing has become more commonplace, it has not reached a level where it can manufacture instruments in a high-quality yet profitable way,” said Smith. “We won’t be replacing CNC machines anytime soon with AM.”

Future Challenges

The ability to foresee capacity challenges into the future will be a major challenge for orthopedic device manufacturers.

“This business is rarely high-volume, low-mix,” said Thomas. “It is often more high-mix, low-volume. Changeovers are really important, as well as adapting to customer’s changing requests and forecasts.”

Viant has invested in Kinaxis, a best-in-class forward planning software platform, to help the company properly plan for material needs as far in advance as purchase orders and forecasts will allow. “Kinaxis gives us an end-to-end view—allowing us to aggregate data, look at historical forecasts, and model different scenarios to evaluate and update capacity issues,” said Andrew Thomas, senior director of operations for Viant.

As an example, Thomas continued, “let’s say we get a customer that would like to transfer business to us. Within 15 minutes, we can determine if we have the in-house capacity to support that, to level load, and to know whether or not Viant needs to make an investment. 15 minutes! That’s hugely beneficial and impressive to our customers. Because when it comes down to it, you could make the best product in the world, but if you are two months late getting it to the customer, what good is that?”

DFM will take on a greater role as complex designs become more challenging to make and speed-to-market stays a top MDM priority. Figuring out a cost-effective approach to make these innovative products often challenges CMs to push the limits of machining in creative ways. However, perhaps the greatest challenge to machining firms is maintaining efficient, productive operations without enough qualified workers.

According to Tony Freeman, president of A.S. Freeman Advisors, a New York, N.Y.-based consulting firm to precision manufacturing industries, the labor shortage in medical manufacturing is currently two shortages. “The first is the decades-old dearth of skilled technicians: master machinists, floor leads, programmers, and manufacturing engineers,” said Freeman. “There is nothing new about this situation. A second shortage has occurred with the COVID-19 pandemic. Device manufacturers find themselves unable to hire semi-skilled and unskilled staff for positions on the production floor. When these workers can be found, they often require wages $3 to $4 an hour more than was paid before the pandemic.”²

The challenge of finding qualified labor will remain a vexing problem for manufacturers for years to come. “Utilizing more efficient technology and software, like five-axis palletized machines, allows us to automate where necessary, reducing the challenges that the lack of qualified workers presents,” said Blackwell. “More automation means we are less dependent on labor. By continuing to use more advanced technologies, we are also able to move innovation forward in both our processes and products.” 

References

1. mck.co/3wOUh6q
2. bit.ly/odt220942

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Mark Crawford is a full-time freelance business and marketing/communications writer based in Madison, Wis. His clients range from startups to global manufacturing leaders. He also writes a variety of feature articles for regional and national publications.