08.02.07
Laser Processing: Finding Its Orthopedic Focus
Device manufacturers apply laser technology to solve a variety of production challenges.
Jennifer Whitney
Editor
Pop quiz: Did you know that the word “laser”—characterized by mainstream dictionaries as a noun—actually is an acronym? Give yourself an extra point if you can define it (answer: LASER = Light Amplification by Stimulated Emission of Radiation).
In laymen’s terms, a laser is a tool used to create and amplify a precise, intense beam of light. In consumer applications, lasers can be found in everything from barcode scanners in supermarkets to computer printers and CD players. In medical practices, laser light beams also are being used in procedures for vision care, dentistry, cosmetic surgery and more.
Medical device manufacturers have been using lasers for decades to cut and bore metals and other materials. The quality of cuts and welds, along with the precision and repeatability, offered by laser technology has helped many manufacturers reduce secondary clean-up operations, reduce changeovers and keep costs reasonable.
Lasers have various uses in orthopedic manufacturing today. In the photo above, laser machining removes silicone material off an orthopedic surgical instrument. Photo courtesy of Molded Rubber and Plastics Corp. |
The boom in minimally invasive surgery has brought various documented challenges to manufacturers being pressed to bring to life tiny components and complicated geometries never tackled before in the industry. Lasers are being used to achieve a number of means in the manufacturing process.
“The push to create smaller and smaller parts caused us to transition,” said Greg Riemer, vice president of business development for Molded Rubber and Plastics Corp. (MRPC), based in Butler, WI. “About five to seven years ago, we looked into what types of technologies were available to create those features and identified lasers as being of the best candidates.” His isn’t the only company to recognize this.
“What we continue to see is that minimally invasive technologies are finding ways into orthopedic applications,” said Steve Iemma, president of Accu-Met Laser in Cranston, RI. And that, in turn, creates a need for technology that can work in extremely tight tolerances while offering a precise, repeatable result. In recent years, Accu-Met has worked with spinal and shoulder instrumentation as well as items such as suturing devices, among others.
Spinal innovations are one type of technology benefiting from laser welding. The spine community has evolved in its approach to treating problems by moving from the creation of “passive” spine devices used for fusion procedures to those that are more active and mimic motion (ie, motion-preservation technology). “To do that, you need to assemble the devices in a way that lets them uphold a lot of stress and fatigue,” said Kevin Hartke, director of sales and marketing for Mound Laser & Photonics Center (MLPC). “We can hermetically seal devices while offering strength in the pieces put together.”
Peridot Corp. also has been working with spinal technology. “Right now, we’re doing a lot of tubing work for instrumentations for spinal procedures,” reported Debra Van Sickle, vice president of Peridot. Another project she recalled involved lasers being used to make “scooping devices” that help remove damaged parts of a herniated disk. “A laser can get in there with light waves and make beautiful patterns,” Van Sickle added.
The company has been working on a variety of other applications as well, including surgical instruments and battery contact work for prosthetic devices and handheld surgical equipment.
Laser marking is a popular service, as it is capable of creating durable—and tiny—markings for essential information. Shown above is a disk shaving instrument featuring laser marking. Photo courtesy of Seabrook International. |
Although not such a glamorous role, lasers also have a very important function in the era of traceability. Laser marking and etching are processes often used to imprint serial numbers, company logos and other information directly onto a product.
Contract manufacturers, which offer a variety of services under one roof, find themselves inundated with customers seeking this service. “Traceability is such a critical requirement, and laser marking has been an explosive area for us in that everything requires lot traceability and numbers. Bringing that service in-house has greatly enabled us to not only support our production requirements, but also our prototyping requirements,” reported Jack Fulton, sales director for Specialized Medical Devices, LLC in Lancaster, PA. His company works on a lot of small bone implants for hands and feet, as well as spinal implants, and the components such as pegs and screws can be especially tiny. Using lasers on both metals and plastics, Fulton said this method offers more control and less disturbance to the surrounding material than traditional engraving and stamping processes.
Seabrook International, a full-service provider of surgical instruments and implants, similarly has been offering laser-marking services for the past eight years. “Done properly, you can achieve the proper contrast that’s important in an [operating room] setting, where bright light and glare can be an issue,” noted Paul Barck, president of the Seabrook, NH-based company. “A lot of work goes into instruments to give them a smooth and cleanable, yet non-reflective surface finish. Laser marking provides durable marking with very good contrast, so the information is easy for surgeons to read.”
Growing Laser Usage Brings Benefits
Although the invention of the laser by a Bell Labs researcher and consultant in 1958 led to a multi-billion dollar industry that now offers an array of lasers ranging from tiny semiconductor devices the size of a grain of salt to huge machines the size of a living room, the orthopedic industry has been slower than others to adopt this technology in its everyday manufacturing operations, probably simply because the community is more familiar with other technologies. However, as engineers and other professionals learn more about what lasers can do to streamline operations, this technology is gaining ground in the construction of surgical instruments, implants and other medical components.
Many providers of laser services who spoke with Orthopedic Design & Technology compared the evolution of the technology over the years to that seen in electronics and other industries. “We used to see big machines with a big footprint on the floor space,” said Iemma of Accu-Met Laser. “It wasn’t unusual to have a big machine that was difficult to maintain. But the quality of the electronics has evolved. Now [some laser centers] are about the size of a two-drawer file cabinet with a fiber optic cable.”
That’s not the only difference, Iemma said. “The sheer user-friendliness of lasers has evolved tremendously in the past 20 years. The motion-controlled industry [eg, aerospace] has done a tremendous job to create software that drives the positioning system that the laser needs to take advantage of what the laser can really offer.”
Hartke of MLPC has worked with lasers for more than 10 years, since his background is in engineering. In his experience, “The lasers I started with were tweaky, and their performance varied day to day,” he said. “Lasers today are very easy to work with, they’re very reliable and very robust. There’s a lot of advantages from the reliability standpoint alone.” And it’s only going to get better, he promises.
Pleasanton, CA-based Peridot Corp. has found that lasers have begun to approximate the accuracy of processes such as wire EDM (a process by which wire is heated to a point where a spark is generated and used to ablate metal). Lasers often can achieve the same effect in a quicker timeframe. “Some applications only lend themselves to EDM only due to its precision,” said Van Sickle. “However, the number of hours it takes to cut material is much longer than with a laser. It may take 50 hours to process a part with EDM, whereas a laser might take 15 hours. Speed equals lower cost.” As a result, she added, “Lasers are no longer the last resort—they’re the first thing we think of now.”
Peridot isn’t alone in this line of thinking. Miamisburg, OH-based MLPC started working in the orthopedic industry about seven years ago with laser marking of components used for surgical instruments and some implants. The proximity of the Dayton, OH region, long known for its tool and die presence, offered the company a strong tier-one supply base looking for new opportunities as its stronghold in the automotive industry began to decline. “We were one of the only suppliers in the area who were already established in orthopedics,” explained Hartke, who additionally noted that the company concurrently began developing relationships with OEMs that were gaining interest in laser technology. Now the company does a lot of work using lasers to create surface textures on implants as a means of promoting bone adhesion. “Surface texturing primarily is the biggest area we’re working on in orthopedics,” Hartke reported.
Along with this trend, in 2002, MLPC identified an opportunity to introduce laser welding, which can create fusions as small as 10 thousandths of an inch, Hartke said. “Laser welding is by far our fastest growing business, and we’ve brought on a lot of equipment to support that,” he noted.
Accu-Met is another provider of laser welding, which comprises about two thirds of the company’s business, according to Iemma. Benefits of laser welding include low heat input and “virtually no thermal distortion as a result of that,” he said. In addition, the method offers a relatively easy fixturing approach that lends especially well to building prototypes—especially when heat sensitivity could be an issue. Furthermore, laser welding helps eliminate the need for extra material when joining components. “A lot of times I have seen designs that allow for filler metal that you’d see in a traditional design,” Iemma said. “We work with engineers to optimize their design for laser processing.”
Some companies that don’t come to mind as laser experts now are offering laser services in conjunction with processes that are more in line with their core competencies. MRPC, for example, is known to the medical device industry for its molding and tubing capabilities. Having recognized that OEMs seek outsourcing partners who are able to manufacture ever-smaller parts in recent years, the company realized that laser processing could help MRPC take molded parts to the next level by picking up where molding’s capabilities leave off.
In orthopedics, MRPC has various customers needing tubes, gaskets and other components used for minimally invasive procedures such as arthroscopy. “Some molded features may be too small to build from a tooling standpoint,” explained Riemer. “We’ll mold the part and then go back with the laser to modify the component in a precise, repeatable manner.” In this case, he’s referring to the process of flash removal, which involves eliminating the web of unwanted leftover material that often remains once a part has been molded. Whereas operators used to have to examine a part under magnification and use a blade or scissors to manually pick at the flash and pull it off, lasers offer an automated process by which the operator simply programs into the computer what’s needed and the laser precisely targets the debris for removal.
“We do a fair amount of over-molding of rubber or silicone onto metal,” Riemer said. “That process lends itself to flash possibilities due to tolerance stack ups. If you have a metal insert in a rubber tool, there’s always a tolerance range. If plus or minus a thousandth [of an inch], the metal part could be on the low side of tolerance, and as a result create a small gap in the mold for the material to flow into, and thus create flash. With our lasers, we can very precisely remove that excess material without compromising the integrity of the part. Lasers are more critical when you’re talking about smaller parts with tighter tolerance, because the laser is repeatable and highly precise.” In addition to flash removal, MRPC often uses its CO2 lasers to pierce holes or cut small features into the tubing, or to fabricate other features. The benefit, Riemer said, is that lasers offer the company the ability to produce holes that are two to four thousandths in diameter. “If we were going to tool that, it would be almost impossible,” Riemer said.
Laser micromachining, a process in which lasers remove material to create very small features on components—including parts about five microns in size—is another process that’s catching on because it sometimes can more easily tackle features that might be more difficult to achieve using mechanical machining. “Once you get into the 25-micron range, you struggle because of the tooling,” Hartke explained. “With lasers, you use focused light to remove material.” Originally developed for the Air Force Research Laboratory, medical device customers slowly are expressing interest in the technology, Hartke said. Although the use of this technology is still in its infancy in the medical realm, he said that laser micromachining eventually (if at all) might be used to help create features for complex textures in orthopedic components.
“What we’re finding out is that anything the body interacts with, it doesn’t understand the material as much as it understands the surface. Surface science in terms of texture is a wide-open field at this point. Lasers are one tool you can use to custom fit textures for whatever application you’re looking for,” Hartke said.
Educating the Masses
Although manufacturers of laser equipment have made many strides with their technology, one of the bigger hurdles in adoption is the lack of people trained to use it. However, MLPC is trying to further the learning curve by mimicking models seen in more advanced regions of the world, such as Europe. In particular, Germany is the epicenter of innovation for laser technology, the experts said, as the country has numerous R&D centers that bring industry and universities together to create and test new technology. Bringing commercialized industries on board means that the groups can work on actual products and refine the laser technology as its being used—all while advancing workers’ knowledge.
Based on that model, MLPC strives to achieve similar goals. With 22 employees on board, Hartke said the company’s goal is to increase that number to 50 staff members within the next five years. And developing its staff expertise figures into its strategy as well—MLPC has several engineering students from universities working for the company as interns who the company hopes that, down the line, as they gain experience in working with lasers, will come work for the company after graduation.
“Our biggest selling point as a company is that buying lasers is just one step. Understanding the technology and having the right personnel is key,” Hartke said. “We have a lot of educated, well-trained people. That’s where we feel we have a competitive advantage and bring out the nuances of how to use the technology. It’s not to say a company can’t bring laser-marking equipment in-house, but they may not realize they can do other things with it. There’s a lot more that goes into the technology than just the equipment you’re purchasing.”
Whereas as recently as a decade ago, laser service providers spent a large portion of their time educating the device industry about the wide range of capabilities lasers offer in manufacturing, now there is a perceptible shift in which younger generations of engineers and designers are familiar with how the technology can solve their problems.
“Through a number of industries, people have turned to lasers as a solution,” Iemma of Accu-Met concluded. “I still get calls from people who don't know if lasers will solve their problem, but lasers do find their way into problems. It’s a solution looking for a problem.”