Faster, Finer, Cleaner
Medical device OEMs in need of complex, detailed partsmanufactured quickly, precisely, and accurately, increasinglyare turning to laser-based processes.
Contributing Writer
Medical device machining is becoming an ever-more-challenging discipline. Medical devices and their components are getting increasingly smaller, while simultaneously being designed with more complex features. The accuracy required for many machining processes significantly is greater than what it was even five years ago. It is extremely important for medical device OEMs to find machining partners who have the technology to be able to keep up with these trends.
A lot of them are turning to suppliers with laser processing capabilities. Compared to other cutting and welding technologies, lasers have a number of advantages, and generally are not cost-prohibitive. It is no surprise that demand for laser processing has increased in the last few years. What follows are someinsights as to why.
Versatility
One of the biggest advantages to using lasers is that they can be used on a wide variety of raw materials. That means that they are applicable to any number of medical device and component designs.
“Most anything, depending on how you design it, can be laser processed,” said Mike Chmura, laser services manager for Litron Inc., an Agawam, Mass.-based laser welding provider. “Your design concept is what determines whether laser processing will be the best method of joining the components.”
Specifically, according to Mike Treleaven, director of applications engineering for Tegra Medical, a Franklin, Mass.-based contract manufacturer specializing in minimally invasive medical devices, “any device that uses tubing or sheet metal in its design can be manufactured using a laser. Many designs use tubing as a raw material, and those are likely to present themselves to use a laser because of its flexibility and ability to make complex geometries and patterns. It lends itself well to minimally invasive designs for those reasons and because it is often a burr-free process.”
Given how fine such designs are becoming, knowing that lasers likely can be used to craft the smallest details can give a medical device design team confidence that their ideas can be made into reality.
“You can use machining for practically any substance, including exotic materials such as titanium and Nitinol, depending on what you want the part to look like,” said Hadi Lalani, vice president of AMTEC Inc., an Anaheim, Calif., supplier of manufacturing services, including lasers. “Laser processing is best for very fine drilling, or if you have very small part geometries. If you are working with a 40-50 micron web, laser will do the best job.”
Mike Adelstein, president and CEO of Potomac Photonics, a provider of micro manufacturing solutions based in Lanham, Md., agreed.
Laser processing is an ideal technology for manufacturing medical devices, especially those that require miniature features between one and 300 microns, according to Adelstein. By comparison, a human hair is 75 microns.
“A benefit to lasers is that they are very versatile,” he explained. “Depending on what wavelength you choose, they can be appropriate for many types of materials. Certain technologies can only machine one type of material. With lasers, if you have all the possible wavelengths in-house, you can machine all different materials. Their flexibility makes them favored by engineers who design medical devices. They know that whatever they have to do to make their device biocompatible, there will be a machine that will enable them to get that device made. It just requires changing features on the software to make any changes that they might require. From prototyping to production, lasers are becoming more prevalent and less expensive for those looking to find a cost-effective way to manufacture at any volume.”
Categories that are strong candidates for laser cutting and welding include:
• Stents;
• Cannulas;
• Laparoscopic instruments;
• Catheters and delivery systems;
• Connectors;
• Assemblies;
• Pacemaker, defibrillator, and hearing-aid components;
• Components for durable medical equipment; and
• Metal, polymer, and ceramic components.
They also are being increasingly used in marking applications.
“Before, marks had to be machined or printed, but this way, you get a more robust mark that lasts longer and doesn’t fade,” Chmura said. “This is important because reusable medical devices have to go through autoclaving, and laser marking is able to withstand that process.”
Geometry Issues
The ability to work with very small geometries is perhaps the biggest calling card of laser processing. Not surprisingly, the lasers themselves have gotten smaller and more precise in the last few years.
“As medical components get smaller, the spot size of the laser has to get smaller,” Chmura said. “The response to the demand for smaller spot sizes has been the use of diode lasers, which have become more popular in the last five-10 years. If you compare today’s implantable devices from the same ones 10 years ago, they are one-fourth the size now. Every technology that goes into them has gotten better. And lasers have had to keep up.”
Developments on this front continue to progress, said Dan Capp, vice president of sales development at Laserage Technology Corporation, a laser firm based in Waukegan, Ill.
“There is always R&D going on with laser equipment. Recent output includes smaller-sized laser beams,” he said. “That continues to allow us to put smaller features on smaller parts. Everyone wants smaller parts and a smaller package.”
Speed Issues
Another benefit is the laser process usually can be completed quickly, so that even the most outrageous prototyping and production demands often can be met. The introduction of a faster technology called femtolasers really helped in this regard.
“The advantage of using laser cutting and scoring is that the processing speeds are relatively high, thereby minimizing cost when the technique is appropriate,” said Jim Schienle, medical product manager at CoorsTek Inc., a maker of ceramic components in Golden, Colo.
This also means that laser processing can fit rather easily into a firm’s Lean manufacturing strategy, said Jens Trötzschel, business unit manager for metals and machining at Heraeus
Medical Components, based in Hanau, Germany.
“Machining and laser processing provide flexibility for innovation-driven medical OEMs,” he said. “The time-to-market features of these technologies can drive the design process quickly to candidate designs. After functional performance has been prototyped, these processing technologies can address capability and six-sigma goals using the lean manufacturing tools available today.”
Speed also is an advantage to laser welding, said Chmura.
“When it comes to laser cutting, specifically of tubing, we have a process whereby we can do frontend and backend work on a part simultaneously, and it’s timed in a way that you don’t have to rely on the operator to position the part correctly,” he said. “This, along with our conventional machining capabilities, allows for a completed part such as a medical tubing device to be completed in seconds rather than minutes.”
A related advantage is that manufacturers can store different kinds of lasers on software programs, making it very easy to switch between them because extra tooling is not required, said Adelstein.
“A major advantage to lasers is their ability to direct write. A medical device company may have a drawing that they send to us, and we can machine it off that drawing without having to make a mask or do chemical etching,” he said. “That gives a lot of flexibility to the engineer that is designing the product. During the prototyping process, we can make changes along the way, needing only to change a software file, not needing to change tooling. For example, one company was developing polymer stents. They were getting ready for clinicals, but they were still doing different design iterations. They sent us a blueprint overnight, and we made the prototype and got it back to them that same day. The production process can be very fast as well. If you are talking about production volumes of 100,000-200,000, lasers can be cost-competitive there. They can machine a product very repeatedly and very cost-effectively.”
Heat Issues
A commonly cited advantage of laser processing is that it does not use much heat. That means that not only is it safer to run than many other processes, it has a much smaller risk of doing damage to the raw material or part.
“One advantage to laser welding is that it transfers less heat into the part than other methods,” Chmura said. “The heat involved is extremely minimal compared to other forms of joining, which may require you to heat up the entire part. Instead, laser welding relies on the intimate contact between the two joining parts to create the fused area.”
“A major benefit is heat input, which is used minimally in laser technology as compared to others. It does not disturb the raw materials, and there is no significant force, as with stamping,” added Capp. “Size capability is another, as you can produce some very small parts with it, but it is still very economical, because you can do it in a number of different environments, such as air or cover gas. You do not have to do it in a vacuum.”
From a cost perspective, perhaps the biggest benefit to a laser process is that is cuts so cleanly that the need for secondary refining processes is decreased. In some cases, they may not be needed altogether.
According to Capp, lasers sometimes can leave a little debris, and secondary processes are needed to eliminate or limit it.
“Medical device customers are always looking for their products to be clean. The perception is that no one will want a device that is not 100 percent clean,” he said. “When a part has been laser processed, you can tell it has been laser processed. The surface features will indicate it. But most medical customers don’t want any sign that it was ever there. So you have to come up with ways to remove them, such as surface treatments and surface finishes.
There are a number of ways to do that, depending on what result the customer is looking for. They may just want to remove oxide, which can be done with an etch. They may want a uniform surface, which can be accomplished through tumbling or microblasting. Or if they want a bright and shiny finish, that can be done through further tumbling or micropolishing.
But each of these extra steps costs money, so it is more economical if you can do a project with minimal secondary processes.”
This is becoming less of a problem thanks to technological advances, noted Treleaven.
“The laser manufacturers continue to improve their systems to be able to cut smaller features, to cut faster, and to produce materials that don’t need secondary operations for cleaning, or minimize them,” said Treleaven. “It can be extremely difficult to clean some components afterwards. That can be as challenging as the process itself. Recent improvements enable the secondary operation of cleaning to be eliminated or reduced, which makes the whole process better.”
“I would argue that the main advantages of laser processing are that it is considered burr-free (though some cleaning may be required), it can create complex geometrical shapes, and it’s fast,” added Treleaven. “That helps when you are designing a disposable device, because in those cases, speed and time equal money.”
Overcoming Challenges
Smaller and more detailed medical devices and components present a number of obstacles that can derail a manufacturing plan if not accounted for properly. Even though machining and laser processing can alleviate many of these issues, they still must be accounted for.
Perhaps the toughest is figuring out how to hold such tiny pieces in place when performing such a precise process on them.
“The biggest challenge for machining is the intricacies of the products,” said Lalani. “The designs are sometimes very complex. You need very accurate positioning for your process, because there is very little margin for error.” Trötzschel agreed.
“The biggest challenges for medical device machining jobs include tooling for small dimensions; continuously growing requirements such as quality, complexity, and miniaturization; and process capability,” he said. “Keeping pace with the trends to miniaturization of components is the need to upgrade measurement and instrumentation systems for in-process, final, or receiving inspection systems in the quality departments. A major challenge is to provide customers the flexibility and speed they desire during the development stage while assuring fulfillment of all processes with regard to most enhanced quality systems and process monitoring. As for laser processing, the biggest challenges are the reduction of debris, parameter adaption for optimal process, fixturing, avoiding secondary process steps, and control of the heat-affected zone.”
Luckily, just as laser technology has evolved to satisfy demands for finer detail on smaller parts, it is evolving to meet fixturing issues and other challenges that have vexed manufacturers.
“Companies are developing turnkey systems for fixturing,” said Adelstein. “There has been progress related to the field of machining in different types of environments to make products cleaner and ensure that materials remain intact and are not melted or damaged during the process. Lasers are becoming more reliable and less expensive. The technology is becoming accessible to a broader range of people to use it. There is more range to it than there was two or three years ago, and it is more capable of doing things than it was previously.”
Expanded Opportunities
The medical device design process grows more complex each year.
“Technologies are always changing, and there is always a demand for more accuracy, consistency and repeatability,” said Lalani.
If OEMs are not working with a supplier knowledgeable about how to capably manufacture these designs, they run the risk of choosing the wrong process, which can cripple a product's development and waste money.
“No one manufacturing technology is best for all aspects of today’s high-performance and cost-sensitive designs,” said Trötzschel. “Medical device OEM designers are driving materials and processes to their limits as minimally invasive surgical procedures are taking on new dimensions of accessibility, flexibility, functionality and robustness. Working with a vertically integrated supplier offering medical-grade materials expertise, whether with plastics, metals or coatings, and a breadth of component manufacturing and assembly services assures customers that best processes are given a priority at every step of the process. Those suppliers can take a matrixed approach, providing cost-driven solutions that scale seamlessly from design verifications to clinical trials to pre- and full production for a global product launch.”
Indeed, working with a supplier who is well up on the latest developments regarding what lasers are capable of can even be a help in a medical OEM’s design process.
“Our customers are becoming more aware about what laser manufacturing can provide them,” said Treleaven. “Before, a customer might design something but not be sure how to manufacture it, and then have to modify their design so that they can use lasers as opposed to EDM (electrical discharge machining) or conventional machining. Now, the engineers who design parts are educated enough that they are aware of what laser can offer. They can design specifically to use a laser. They know that it generates low-cost but highly complex components. That has expanded the opportunities for laser manufacturers.”
Erik Swain is a freelance writer based in Phillipsburg, N.J. He has covered the medical device industry for 13 years.