Some of the new designs in cardiovascular, orthopedic, neurology and other device disciplines would not have been conceivable as recently as five years ago because there was no way to manufacture them with existing technology. But machining and laser processing providers have embraced new ways of manufacturing parts, making these complex products a reality today.
This is incredibly important because these new technologies are producing annual growth rates in the double digits, or have the potential to do so, in contrast to legacy products that may provide steady sales but not robust growth.
Many of today’s most innovative medical devices have incredibly precise specifications that only can be executed by equally precise manufacturing technology. These devices not only require tight tolerances, miniscule wall thicknesses and odd shapes, they also require special materials. It’s not as simple as finding a better way to cut metal.
New technology allows for increasingly smaller and detailed parts. Photo courtesy of Johnson Matthey.
Platinum-based alloys are particularly popular, he said.
“Recently, there has been a push to incorporate many internal features into the design of the components we manufacture,” he added. “For instance, think about the challenges of precisely locating multiple (as many as eight) burr-free, centrally intersecting through-holes, which run around the circumference of precious metal tips less than .100 inches in diameter. This has spawned the need to develop highly precise secondary operations, where the design of the fixtures necessary to hold the component is just as critical as the machining operation itself.”
That means the parts must be free of burrs and machined in a way that little or no force is exerted on to the piece being made. As a result, according to Morley, companies like Johnson Matthey are focusing on two technologies that can accomplish that—electrical discharge machining (EDM) and laser machining.
EDM is an erosive process that allows suppliers to make parts using no force impact.
“Some parts have gotten so small, that if you use any force to cut them, you will destroy them,” explained Michael Ehrlinspiel, chief technology officer of Memry Corp., a Bethel, Conn.-based provider of nitinol materials and processing services. “So EDM works very well, for instance, in making small holes for nodules and even small cross sections. You can’t produce features like that with lasers, but doing so with wire EDM yields very favorable results. It is no surprise that we are seeing more business for wire EDM processing of nitinol.”
Herb Bellucci, CEO of Pulse Systems LLC, a laser provider based in Concord, Calif., noted that “materials guys are driving decisions on the laser side” because there are so many new materials and designs in play right now.
“There are several challenges at the limits of our capabilities. One is long catheter structures. These are complicated and time-consuming devices to fabricate, and speed matters. Some of these catheters, especially ones for the femoral artery, are five feet long,” he said. “In orthopedics, we are starting to dabble with more interesting devices than what we had seen. But ortho devices tend to be very structural. They have to support the weight of the body, so they tend to be very robust. That means thicker materials, and more challenging materials like titanium. That’s where industrial-strength lasers come into play. We are seeing more bioabsorbable materials and plastics in general, as some companies are developing replacement materials for metals in some applications, so that means greater requirements on the fabrication side. What was once a metal structure with a plastic jacket may now be an integrated wire form extruded inside of plastic materials.”
Given these demands, there have been radical changes to machining systems in recent years, especially laser processing ones. A number of new technologies have emerged.
“The most significant new development in laser processing has been the advent of ultrafast lasers that are actually ready for use in production and not just laboratory instruments,” noted Sarah Boisvert, a fellow of the Laser Institute of America and a consultant to several laser providers. “Companies such as Radiance of Petaluma, Calif., have led the way, developing a laser from solid design-for-manufacturing principles. While at the high end in terms of price, Radiance lasers have the reliability, easy user interface and technical parameters for demanding production line use.”
Improvements in cost and efficiency have led to the rapid adoption of new laser technologies, says Mike Adelstein, president of Potomac Photonics, a Lanham, Md.-based laser-processing firm.
“Lasers continue to improve. The cost of lasers was extremely expensive, so mechanical processing made more sense. But now that the cost of light has gone down, lasers have become more cost-effective for customers,” he said. “One area of improvement is fiber lasers. In the past, you needed excimer lasers that used gas or solid-state lasers. But now, fiber lasers have improved the technology and made laser machinery more of an option. One of the advantages of fiber lasers is that they can do jobs in the microns, which is important as medical devices continue to get smaller, especially implantables. Lasers are what make the fabrication of things like implantable wireless devices possible.”
Some parts require such precision and are so fragile that they cannot withstand much (if any) force or heat, whose effects might warp or destroy them. So many of the most significant innovations of recent years have to do with finding ways to cut and shape parts without disturbing them at all.
For example, Norman Noble Inc., a Highland Heights, Ohio-based microprecision contract manufacturer, introduced an athermal laser technology called Noble Ultralight. The technology, which does not produce any heat whatsoever, is being used to manufacture bioabsorbable polymer-based implants that could not be made with laser machines using traditional systems, said Brian Hrouda, the firm’s director of sales and marketing. Applications include stents, drug delivery systems, catheter valves, and needles.
It is a cold ablation technology, he noted.
“Light pulses strip electrons from the target molecules. This photo-ionization subsequently causes material to be electrostatically ejected from the target without causing any collateral damage to the surrounding material,” Hrouda explained. “It is a proprietary ultrashort pulse laser that, because it does not generate any heat affected zone, reduces, and in some cases eliminates, costly deburring and post-processing steps and increases product quality and yield. The ultrafast laser process enables the machining of features in materials used to manufacture vascular stents with minimal variability and without the introduction of heat inherent in traditional thermal laser manufacturing.”
While nitinol tubing is a mature, high-volume market, it has seen incremental improvements in recent years to meet the challenges presented by new designs from OEMs, Ehrlinspiel explained.
“For example, we can now make very, very small-OD (outer diameter) tubes, as small as .0010 OD, to help make very small stents that are used to build a scaffolding in wide neck aneurysms or other cerebrovascular structures,” he said.
The key to that process is short pulse lasers, which only have become available in recent years. The laser cuts with high-density light packages in short pulses, which allow precise cutting without the adverse heat effects of traditional methods. This technology vaporizes the material and as a result prevents the formation of slag. Extra processing, such as deburring before electropolishing, can be eliminated or at least significantly reduced, saving time and money.
“This means that short pulse laser technology now enables new types of products that simply were not possible before,” explained Ehrlinspiel. Wall thicknesses as small as .001 in. is now feasible, which means smaller designs can be executed.”
Bellucci has noticed many significant advances as well.
“The technologies of interest lately include short pulse lasers such as the Radiance femtosecond laser,” he said. “It is useful for machining stent structures, especially those with polymer-based bioabsorbable materials. We are active in the area of high-peak-power pulse lasers. They provide the benefit of cutting nitinol and precious metals, and in general provide faster cutting speeds. It has improved the quality of cuts on tubes. Fiber lasers are the real state-of-the-art for medical. They can accomplish brute-force cutting. These have impacted industrial applications and inevitably will have a significant impact on medical device manufacturing. Some are moving to kilowatt lasers, which offer high-end industrial sheet-metal power in a package for medical device manufacturing. That could have a tremendous impact on our business. That opens the door for a very interesting combination of technologies.”
New Internal Processes
There always is a drive by suppliers to improve internal processes that lead to lower costs and better efficiency. One of the biggest drivers is trying to minimize or eliminate the steps between laser cutting and electropolishing.
“If you laser cut a part, the process deposits an oxide layer on it. You need to remove the oxide layer before performing a heat treatment,” explained Ehrlinspiel.
Traditionally, suppliers have used microblasting, which removes the oxide layer via abrasive particles. But it’s not an ideal solution. It’s a dirty process that requires cleaning afterwards, and results can be quite variable. Few engineers prefer this process, but it had become a necessary step before electropolishing.
Now, however, suppliers are looking at ways to remove oxides via chemical treatments. One way is etching. Traditional treatments could be inconsistent and often used toxic ingredients.
“But in the last three or four years, there have been significant improvements in this area,” said Ehrlinspiel. This has made etching an attractive alternative to microblasting, and a better, cheaper process.
The electropolishing process itself also has undergone extensive changes in recent years.
“Up until now, hazardous materials, low temperatures, and expensive equipment were all required,” he said. “And it was very much trial and error. Now, chemical experts have made repeatable recipes that are safer and easier to run, especially at room temperature. The chemicals are less hazardous, and fewer steps of treatment are required. When you take all of this together, one can see that there has been a tremendous move forward in the process of electropolishing.”
The next revolution in efficient design and manufacturing of machined and laser-processed parts could come from a better understanding of fatigue characteristics.
A challenge with nitinol, especially, is determining its fatigue characteristics, especially for products subjected to potential fatigue-related failure. Large-diameter stent grafts are just one example of this.
Interventionalists need to know how long a nitinol stent-graft used to treat abdominal aortic aneurysm can be expected to withstand the high-pressure environment of a diseased aorta. There is little room for error and a miscalculation in this clinical setting could have serious consequences for the patient.
But now the nitinol business is more used to finite element analysis to predict a nitinol product’s fatigue characteristics. This has become an important tool in product design.
“Now you can go in to the design process with a better sense of what the risks are to make parts out of nitinol tubing,” Ehrlinspiel said, adding that suppliers are further optimizing the technique to account for the positive effects of short pulse laser cutting on thick-walled tubing.
“With improvements in materials, we can expect devices to last longer,” said Giorgio Vergani, general manager of SAES Smart Materials Inc., a manufacturer and supplier of shape memory alloys, smart material and high-purity alloys. The company, based in New Hartford, N.Y., is a sister company to Memry. “That is vital in critical devices like stents and cardiac valves. More so, increased knowledge about fatigue could lead to progress in the way that components are engineered.”
Another driver is to improve the cleanliness of material, said Vergani. OEMs that need nitinol in their devices should work with a supplier that follows ASTM F2063-05, which sets forth standards for Wrought Nickel-Titanium Shape Memory Alloys for Medical Devices and Surgical Implants.
“It is advisable that the cleanest nitinol be used in the manufacturing of critical U.S. Food and Drug Administration-regulated devices,” he noted. “That is in keeping with how our medical customers have always asked us for the cleanest nitinol. The definition of ‘cleanest’ may be different from customer to customer, but nonetheless it is a major driver for this business.”
Indeed, SAES places such a premium on cleanliness that it is investing research dollars in developing cleaner Nitinol and understanding the links between inclusions and fatigue, which could eventually enable the quantification of the benefit of micro-cleanliness.
Another area of interest is developing lower-cost alternative alloys to platinum, said Morley.
“While the benefits of incorporation of precious metals are many, the inherent cost of the raw material has limited their applications to all but the most critical devices,” he said. “Recognizing the benefits of using platinum alloy, which has enabled the long-term implantation of many stimulation devices, our customer base has been very keen to evaluate alternate platinum group materials, which behave in a similar fashion to platinum when implanted but come along with a lower raw material value. Ideally, this would allow our customers to lower the cost for existing components and use a lower-cost material in a greater number of applications.
However, developing the machining capabilities associated with a new alloy can be tricky.
“Precious metal can tend to gall and be difficult for traditional machining techniques, these materials often have little or no response to electropolishing or passivation,” said Morley. “For some of these reasons EDM and laser (low-force, no-contact, and micro-scale) can be ideal methods for machining precious metals, particularly when features might be as small as a .004 in. through-hole, for instance.”
Given all the research and development going on, it is no surprise that OEMs and their machining suppliers have started working together more extensively. Indeed, many OEMs are demanding that machining and laser processing firms get involved in other aspects of the manufacturing process and the supply chain.
“Most of our customers seem to be seeking vendors who have multiple processing capabilities under one roof, and more importantly operate under one quality system which recognizes the specific requirements placed on this marketplace by FDA,” said Morley. “No longer can a machining operation seek long-term success by focusing on the `stack them deep and sell them cheap’ mentality, looking to take advantage of commodity technology and make up for slim margins with high volumes. It is becoming more and more expensive for medical device manufacturers to qualify and maintain a large vendor base. The quality requirements of a vendor expecting to participate as a supplier in the medical device market are very specific. All this is leading to vendor consolidation, and the more a vendor can offer, the more likely they will remain a key supplier. Offering multiple machining operations all controlled under one quality system, therefore, reduces the cost to a customer of dealing with a given vendor when procuring components and will be key to maintaining critical supplier status. ”
“Customers are always looking, especially in this economy, for costs to go down, and for laser suppliers to do more than just laser technology,” he said. “We have been branching out. We have brought in 3-D printers and CNC machining systems to complement our laser technology.”
This is not only a necessity now, it will only become more important down the road, said Bellucci.
“We are in a position to provide service to customers who want a turnkey solution. The trend in contract manufacturing is for more highly integrated supply solutions. They want a more complete solution, further down the supply chain. So we offer secondary processing and other complementary services,” he said. “We also do laser welding, which is an assembly solution. We have started to do small-part machining so we can supply other components for their subassemblies. That provides us more opportunity to achieve more value. Combinations of technologies are being integrated, such as lasers and robots, lasers and machine tools. It will be interesting to see how that plays out over the next decade.”
A close collaboration also can ensure that there are no surprises when it comes to cost and quality.
“Collaboration early in the planning process is key to selecting manufacturing processes which will ensure the long-term lowest cost of ownership for a given component,” Morley said. “We work with our customers to ensure that the manufacturing process selected is appropriate to manufacture the component in the necessary volumes to the tolerances specified by our customer’s design. For instance, the most efficient machining method for placing a slit along a cut band when making 10 parts might be a wire EDM. However, for 10 million parts, we might suggest manufacturing on a laser where the programming and setup might initially be greater, but the savings in cycle time to manufacture the part could be significant. Once a process is established and a customer has submitted their device for premarket approval or 510(k) approval, they are loathe to allow any changes to either the design of a part or the manner in which it is manufactured.It is, therefore, critical that the vendor and the device designer collaborate early on to ensure that the manufacturing processes selected by the vendor are both capable of achieving the tolerances set out on the print and making the parts in the anticipated volumes.”
Device designs have changed radically in recent years due to technological advances, and machining and laser processing technologies have changed as well in order to keep up with them.
None of this would have been possible without a group of OEMs and a group of suppliers who are keenly attuned to what each other needs to make a breakthrough concept a reality.
This connection is only going to grow stronger, and both sides need to keep in close communication as to what new designs are coming and what is needed from a technological standpoint to get them manufactured and on the market.
“All of these things require a significant investment,” said Bellucci. “But if you’re going to spend your money wisely, you have to anticipate which technologies are going to be the most significant. Placing the right bets is a major challenge. You have to predict where the medical device industry is going.”
New machining and laser processing equipment requires an intense capital investment, so failing to communicate your needs properly may mean not being able to find a partner who has the right machinery to make your new product.
Erik Swain is a freelance writer based in Phillipsburg, N.J. He has covered the medical device industry for 14 years.