Features

Leading the Pack

By Mark Crawford, Contributing Writer | September 20, 2016

In the face of ever-increasing challenges and demands, machining is still the top process for orthopedic manufacturers.

As medical products become more complex, shrink in size, and incorporate advanced materials, machining and tooling vendors are feeling pressure from their customers to deliver more services, with shorter lead times, at lower cost. This is an increasingly tough challenge. Achieving these goals takes ongoing investment in new or improved technologies, and deep operator talent and creativity.

On the OEM and R&D side, the emphasis is getting products to market faster than the competition, while keeping costs down and maintaining regulatory compliance. For the machining industry, this means providing rapid prototyping capabilities and being able to process new (and expensive) metals and plastics effectively, with increasingly tight tolerances. In addition, because making complex, higher-precision products puts pressure on machining labor and time, its even more important to be ISO-certified and to embrace lean initiatives, with a constant focus on quality assurance.

Although manufacturing is still super-charged over the potential of additive manufacturing in general, and 3D printing in particular, the orthopedic industry is still largely reliant upon (and comfortable with) proven machine, tooling, and cutter technologies. For example, Peridot Corporation, a Pleasanton, Calif.-based provider of medical device component machining and cleanroom assembly, reported that its computerized numerical control (CNC) machining, electrical discharge machining, and laser processing projects increased 20 to 30 percent compared to last year, driven by the rise in minimally invasive spinal implants and tools, as well as small bone fixation. Startup activity has also been strong, leading to new machining business.

Shorter Setup, Shorter Cycle Time
To meet ever-present demands for shorter lead times and tighter tolerances, machinists must invest in the technology or know-how they need to achieve the accuracy, repeatability, tight tolerances, and speed their customers expect. Current trends are toward machine flexibility, quick tool changes, higher RPM spindle speeds, multi-axis metal cutting, and faster table movements.

“Any process that eliminates setup and reduces cycle time also reduces overall cost and delivery time,” said David Cabral, president/owner of Five Star Manufacturing, a New Bedford, Mass.-based OEM/contract manufacturer of high-precision orthopedic implants and instruments. “The marketplace is time-critical and shorter lead times can win the business.”

CNC machining continues to evolve in that direction. Equipment can produce complicated parts that require turning, drilling, milling, and even grinding, all at one station. When a part can be completed from beginning to end on a single machine center, it eliminates unnecessary handling of the part, and time-consuming secondary operations on different machines. This also greatly reduces variance in accuracy and quality.

Multi-axis Swiss machines produce complex shapes and features with high precision and consistency—especially small parts requiring tight tolerances. New versions of these machines can be equipped with laser-cutting and specialized bending equipment. Computers and automation are now being integrated directly into the work benches and cells of Swiss machining centers, providing additional flexibility. Implants or other products can even be created using data from medical scans or medical computer models, downloaded directly to the machine. A key to improved speed and efficiency is investing in large banks of live tools that can produce complex and sculpted shapes, a resource that contributes to shorter setup times and faster job changeovers. Automation, including robot feeders, can allow for 24/7 operation of CNC 5-axis milling centers and other equipment.

Swiss machines are also being equipped with high-pressure coolant, making it easier to machine harder engineered materials such as high-temperature alloys, stainless steels, and tougher plastics like polyetheretherketone (PEEK). These high-pressure coolant capabilities—up to and exceeding 1,000 PSI—are highly favorable for gun drill-type tooling. Parts can be almost completed with very thin walls and drilled without removing them from the machine.

“Run-out tolerances are held to 0.002 inches over six inches of depth and better with eccentricity between steps less than 0.001 inches, due to applying the right tool for the right job,” said Jeff Augustine, director of new business development for Drill Masters-Eldorado Tool, a Milford, Conn.-based manufacturer of carbide-tipped and solid-carbide gun drills for the medical device industry. “Pilot holes two times diameter in depth and 0.0002-0.0005-inch larger in diameter now make most machines favorable for a gun drill.”

In addition, tool coatings can be used to reduce heat generation, due to the added lubricity they provide to the tool’s outside diameter. When this reduction in heat generation is combined with the significant amount of heat removed with the chips, coolant constraints can be lessened. Specialized dedicated gun drill machines are also being manufactured with chuck-type, part-holding fixtures and counter-rotation of the part to significantly improve hole straightness, size, true position, finish, and run-out.

In Augustine’s view, coatings are not used as much as they should be by clients because it takes longer to manufacture coated tools (about seven days). Most customers want tooling that is readily available from stock and are reluctant to wait for a coated tool, due to the lead time. “The advantage of coatings, however,” said Augustine, “is longer tool life, cooler parts, and much better lubricity. A sharp salesperson will evaluate the customer’s annual usage and present a blanket program that maximizes the advantages of coated tools and eliminates lead times, if that is best for the customer.”

Manufacturers are also relying more on wire electrical discharge machines (EDM) for tube cutting, slotting, notching, and pointing. “We are running five auto-threading submersible machines around the clock, six days a week,” said Patrick Pickerell, president of Peridot Corporation. “The art in this endeavor is being able to design and fabricate efficient work-holding solutions for these often micro-miniature components. We utilize duplicate fixtures that can hold many parts and be hot-swapped, with very little down time between loads.”

Laser-Focused
Laser processing is becoming increasingly vital to orthopedic device development. Solid-state lasers that emit shorter wavelengths are used for precision cutting applications (less heat, tighter tolerances) and can be mounted to Swiss machines. For example, a femtosecond laser can deliver shorter, higher-powered laser pulses at less than 400 fs and leave no thermal imprint on the component.

“Its cold ablation cutting technique bypasses the melt-eject process and removes the risk of heat-related damage to intricate designs,” Shane Strowski, president of Precision Waterjet and Laser, a Placentia, Calif.-based provider of waterjet and laser cutting and fabrication services, stated in a recent article on www.fabricator.com. “The tiny laser beam allows for machining tiny details and reduces the number of finishing steps after cutting—making it ideal for micro-cutting.”

Laser cutting can be faster than EDM machining, with an accuracy of ±0.00001 inches.

“The accuracy and versatility of fiber [optic beam]-delivered lasers make short work of cutting, welding, marking, and ablation of bio-medical plastics and metals,” added Pickerell. “We are using fiber-delivered stent-cutting lasers to produce the cannula used in steerable/flexible, in-the-body devices. Laser kerf widths of 25 microns are now routine.”

Pickerell liked to challenge machinery salesmen by stating that if they could show him a laser that welds, cuts, and marks all in the same work station, he would buy it. “The machine tool companies have listened and these workstations are now on the market,” said Pickerell.

One that Pickerell favors is the Rofin Modular Processing System (MPS) multipurpose laser work station, which comes in four sizes. Its features include an integrated laser source and various modules and motion systems (up to 5-axis configuration) for customized applications in classical laser cutting, welding, structuring and drilling tasks, and high-precision ultrashort pulsed applications.

“These fiber-delivered systems feature increased accuracy and much better processing speeds—about twice as fast,” said Pickerell. “Much less time is now spent cleaning up artifacts of the laser process, such as dross removal.”

Peridot’s laser stent-cutting machines produce features of a size and complexity—for example, creating 25 micron slots in 1-mm-thick material—that are difficult to achieve with any other type of chip-based machining process. Laser technologies continue to be improved for micromachining applications, especially projects that require tight dimensional tolerances, superior edge quality, and high-volume production. For instance, “lasers now can produce precise openings in needles containing unusual tips, as well as puzzle-chain linkages for endoscopes,” said Strowski.

One of the newest laser advancements is Fonon Corporation’s laser-based, non-contact method for cutting glass and other non-metallic, brittle materials on the molecular level.

“Traditional approaches to cutting glass, including mechanical scribe and break, grinding, and sawing with physical cutting tools have been mainstays of glass processing for centuries, which unavoidably result in micro-cracks, weakened surfaces, and glass edges that are highly prone to cracking,” said Ben English, chief marketing officer for the Lake Mary, Fla.-based provider of laser-based material processing technologies. “Our process uses a non-contact laser to create internal tensile forces greater than inter-molecular connections in glass or other brittle materials, effectively separating the material cleanly, without the debris, loss, and quality problems associated with traditional glass processing.”

Waste material is largely eliminated, and the approach works with all types of glass. Edge impact strength increases when glass is cut by this process; the result is up to five times stronger than material cut by mechanical scribe and break methods, according to Fonon.

Work Smarter, Not Harder
Many companies are investing capital to acquire advanced machining equipment to meet the evolving needs of their medical device manufacturing (MDM) customers. This is especially true for products with complex shapes, or that are constructed from non-traditional materials—for example, nickel-titanium alloys are often difficult to machine using traditional methods. Although new equipment can help meet these needs, it can be expensive to purchase and involves a learning curve.

New technology can only take a supplier so far and can add to operational cost—the last thing a customer wants. To keep costs down, it is equally important to review “standard” processes internally and trim costs by improving efficiency.

“Cutting costs by working smarter and not harder will continue to add to the difference in the quoted item that brings in the purchase order,” said Tony Campos, product sales manager for Omni Components Corporation, a precision machining company based in Hudson, N.H.

Working smarter often takes advantage of deep, in-house equipment knowledge and expertise. The Internet of Things is utilizing sensors to measure key operational metrics in real time, which are then analyzed to optimize equipment performance (including setup time) and identify potentially serious maintenance issues before they happen. Should a machine fail, it is prudent to have a validated backup machine, for that particular product, ready to go.

“Setup reduction continues to be a critical focus when controlling overall costs of manufacture and assurance of on-time delivery,” said Cabral. “Our goal is exchanging dies in one minute or less. By measuring overall equipment effectiveness and cultivating creative approaches to programming and machining, we can operate with confidence that our continuous improvement goals are being attained.”

Experienced operators understand that knowing when to pull a tool, and how to reproduce the cutting edges or make adjustments to the angles to accommodate and maximize performance, is essential to maintaining productivity. “Reproducing nose geometries exactly from tool to tool is an art and may require an updated or refurbished sharpening fixture,” said Augustine. 

It’s not always the latest technology that saves the day—sometimes current technology can be optimized to meet client expectations and control costs.

“There is a continuous emphasis on lean initiatives to identify and fix total dollar output per employee,” explained Campos. “Consolidating operations, continuous training and recruiting on multi-axis machines to lower cycle times, scheduling 24/7 operations to meet demands with very little operator involvement, and maintaining constant dialog of understanding with your partner clients are a few keys to staying ahead of the competition.”

Sometimes the solution to a customer request, especially as parts and products become more complex, can be realized through a creative combination of existing technologies. For example, a customer approached Omni about drilling an extra-long thin hole. Omni’s capabilities at the time didn’t allow it to manufacture the part in a reliable way. To solve the problem, Omni invested in a drill pressure modulator. “This device fed a pneumatic pulse through the tool, causing it to peck at the hole,” said Campos. “This pecking routine allowed greater chip control and the ability to drill the hole in one direction, creating an affordable and sustainable solution for the customer.”

In another example of efficiency, it can simply be a practical “planning ahead” function that saves time. Meeting the increasingly stringent and tight tolerances for metal components quickly can be a challenge—and is often dependent on having access to the measuring gages needed to pass the quality assurance (QA) and customer-spec requirements.

“For example,” said Campos, “a spec’d or prototyped screw may involve the screw head having a security designed shape, making it necessary to have the correct tool to turn the head. The QA team will need the gage/tool the customer is using to test the machined screw for meeting the fit and removal tolerances. If that is not available, we must machine the tool or gage ourselves to test the final machined screw, which takes more time and can add to the cost.”

Material Challenges
Advanced materials tend to be harder, creating more wear and tear on tools and slowing down production. Sometimes dedicated machinery and the costly tooling are necessary to be competitive. Acquisition of some materials, such as PEEK, can also be a challenge. Full dock-to-stock traceability is required for all materials through the shop, with particular importance placed upon the handling of the finished product through the value stream.

Pickerell likes the challenge of dealing with advanced materials—using technology and tribal-knowledge know-how about material behavior, built up over years and years of projects. “Adjusting established programming and machining parameters to suit these advanced materials is what makes this business fascinating,” he said.

One of these materials is nitinol, a super-elastic material that is becoming popular for small bone fixation. Another application for nitinol is orthopedic staples, which require large amounts of deflection. This unique material requires machining and forming techniques completely different from other medical stainless steels.

“We shape-set complicated shapes from nitinol sheet, tube, and wire using ovens and fluidized beds,” said Pickerell. “CNC machining of nitinol presents unique challenges that mandate special high-performance tooling inserts and tooling insert coatings.”

Additional machining challenges arise from the gradual shift in the medical device industry toward plastic components and away from metal. Plastics can be difficult to machine because of their sensitivity to heat and lower modulus of elasticity, which requires more vigilance and control by the operator during machining.

“For engineered plastics, individual characteristics must be considered much in the same way as for metals,” said Campos. “For example, what is spec’d for the plastic will determine how much heat it can take before warping, expansion, or deformation occur. In this case, the challenge may be maintaining good heat dissipation and chip removal. Engineered plastics also often require more labor-intensive secondary operations, such as deburring.”

Partner Up
To survive in the competitive orthopedic device market, machine companies must meet or exceed customer expectations. OEMs want more outside assistance
for design, engineering, and prototyping—in fact, they have come to expect it. An increasing number of MDMs also seek more formal installation qualification, operational qualification, and performance qualification (IQ/OQ/PQ) activity reports in response to increased U.S. Food and Drug Administration (FDA) scrutiny. 

For tooling, Augustine reported that many clients are asking for faster delivery on specials and more technical support. “A good field technical/applications support person sees so many different applications that requesting one to come into your facility for an overview of your application is a great benefit to a continued improvement program,” he said. “Interestingly enough, not many OEMs ask for this type of advice, even though it is a complimentary service that we provide.”

Everyone is keeping an eye on additive manufacturing (AM), a disruptive technology that is rapidly transforming other manufacturing industries. What previously took weeks, or even days, to produce can now be manufactured within hours, in a variety of materials, including ceramic. AM processes such as laser sintering and 3D printing are providing design engineers with new options for designing more innovative products—sometimes products that can’t be made using any other fabrication methods. At present, AM is mostly used to make prototypes; however, OEMs and contract manufacturers are excited about its potential for patient-specific implants, which are time-consuming and expensive to produce using traditional machining methods (and will be in much greater demand as the Baby Boomer generation continues to age).

Ultimately, once AM methods are perfected and widely adopted, they are expected to save OEMs up to 25 percent in development costs and get products to market much more quickly. Leading orthopedic implant makers are investing substantially in their own in-house development of AM technologies; for example, Stryker Corp. recently announced plans to build a $400-million additive manufacturing facility.

In the Massachusetts Institute of Technology’s Technology Review, research editor Mike Orcutt indicated that perhaps the biggest potential benefit of AM and 3D printing is the ability to design implants that are specific to an individual patient’s body, printed using data derived from magnetic resonance imaging or computerized tomography scans.

“In the U.S., a few printed, custom implants have already received clearance from the [U.S] Food and Drug Administration, including a total knee replacement and a craniofacial plate,” said Orcutt, who indicated more custom implants are under development. One hurdle, he noted, might be uncertainty over how the FDA will ultimately choose to approach this new class of implants. “So far,” he continued, “the agency has cleared new printed implants that it determined pose no more risk than a product already on the market, but those devices have mostly been made out of materials and based on designs familiar to the FDA.”

Although nothing groundbreaking or disruptive in machining and tooling appears to be on the horizon, that doesn’t mean equipment makers are staying static—they are continuing to launch updated or new equipment.

For now, CNC machining, combined with lasers, welding, and cutting capabilities, will remain the preferred method for manufacturing orthopedic products, at least for now.
“The machine and machine tool industry will continue to develop new machinery and materials that allow for greater capabilities and tooling configurations that result in faster material removal and better surface finishes,” said Cabral. 


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 and is the author of five books. Contact him at mark.crawford@charter.net

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