12.12.05
Casting Call: Change Driven by Greater Demand, Curtailed Costs
Orthopedic casting process responds to implant rise with automation, refinement
Stacey Bell - Contributing Editor
Light. Long-lasting. Low liability risks. The medical community expects today’s implants to meet these criteria while still respecting the tight pricing pressures all healthcare players face. For their part, casting houses have responded to this need by automating more of the casting process and refining the alloys and technologies they use.
While the overall casting process hasn’t changed dramatically in decades, the support activities have. The integration of robotics, flow modeling technologies for gating efficiencies and increased use of computers have provided gains in reliability and repeatability as well as improved efficiency. “We use robotics throughout our operation now and plan to increase their use in the future,” reported Randy Little, director of medical products for Precision Castparts Corp. (PCC Structurals) in Portland, OR. “From using CAD/CAM software to design and create tools, to using robotics in our wax, cut-off and finishing operations, software and automation have tightened the process and created a safer work environment.”
Mike Wyte, business unit manager for Coastcast/FS Precision Tech in Rancho Dominguez, CA, said robotics ties in nicely with OEM goals for greater quality control.
While the aerospace and automotive industries lead development in the casting area, their push for increased use of Six Sigma processes and more modern equipment with more computer controls has infiltrated the medical sector. As a result, more orthopedic companies are seeking highly automated processes that allow them to analyze outputs and fine-tune them in ways that simply aren’t possible with manual operations. “We’re using computers to control temperature and humidity during casting, and we’re adding more controls for pressures and temperatures to our wax press—all to allow for tighter tolerances and great repeatability,” Wyte noted.
Little said PCC Structurals has also embraced Six Sigma concepts. In fact, all engineering staff will be required to reach black belt status, and all supervisors and technicians are to be trained as green belts. “The concept of Six Sigma will become a daily part of our culture going forward,” Little said. (See “Six Sigma: About Those Belts” on p. 19)
Technologic Refinements
The desire among OEMs for improved accuracy and better surface finish is driving another trend: net-shape castings, particularly for knee and hip implants, pointed out Jay Easwaran, president of Indiana Implant Castings in Carmel, IN. “On surfaces that are machine ground to final finish, very little stock is allowed,” he reported. “Customers want to save time and money in removing that last thousandth of an inch—they want to minimize final grinding during the finishing process, and net-shape castings meet this need.”
A range of orthopedic implants and instruments is shown above. Photo courtesy of Doncasters Medical Technologies. |
In fact, Lewis added, while the investment casting process has existed for more than 2,000 years, “the main technologic advancements in recent years have been in process control, offering repeatability, consistent quality and tighter geometric and metallurgical tolerances.” He said Doncasters continues to refine technologic solutions and currently is in the final stages of development for InterPhase, a process that will significantly improve the wear characteristics of metal components when articulating against polyethylene.
Another technologic solution already saving OEMs time and money is computer modeling, or cast solidification modeling.
This technology is a computer simulation tool that predicts how castings will be solidified in the mold and some of the properties that will be attained, including the grain size of the alloy. This capability can give design engineers more control over, and confidence in, casting variations, allowing them to design smaller parts than would have been feasible in years past.
“This process has been used in aerospace for 20 years or so, but it’s really matured over the past 10 years,” said Nipendra (Nip) Singh, consulting partner/CEO for S&A Consulting Group in Cleveland, OH. “All of the big casting houses likely have the software and use it sparingly. Only a few smaller houses aren’t [using it at all]—but they all should be.”
Singh believes all casters should use computer modeling because it provides 95%-plus validity and can shave development time from the traditional four to five weeks to just two to three days. That’s because gaiting trials, and their associated expenses, are eliminated, and the number of iterations can be reduced—all while providing greater reliability.
Finally, today’s thixo-casting process allows casters to improve a product’s properties in a smaller part size. “It allows for a faster solidification process, and mechanical properties can be predicted, defined and improved,” Singh noted.
Capabilities, Challenges
Perhaps the biggest changes in the casting area have occurred in the process used for making alloys. Cobalt-chrome-moly remains the predominant choice, followed by titanium for use in nickel-sensitive applications or where strength-to-weight ratios are a concern.
The casting is shown of an orthopedic implant. A good percentage of the casting process has gone unchanged for decades. Photo courtesy of Doncaster Medical Technologies. |
“Each OEM has a specific chemistry [within the ASTM standards] that it prefers,” Little noted. Casting houses will work with raw material suppliers and OEMs to ensure an alloy’s physical properties are most suitable for a product’s casting process and end use in the human body.
“The most significant refinement,” Little said, “has been the incorporation of AOD [argon-oxygen-decarburization], which virtually eliminates the ‘blackspot’ issue that plagued the industry for years.”
Singh added that new titanium alloys are being created in the aerospace industry and may work their way into the medical sector in the next decade. More exotic alloys—such as zirconium alloys—already are being offered to provide enhanced mechanical properties.
Easwaran noted that the industry has focused on developing new materials not only to improve the quality of implants, but also to improve their longevity. “Alloy research and development is a big trend because older alloys tend to wear out faster and require surgery at 10- to 15-year intervals,” he said. “New alloys change that time frame—lengthening the time of service of these implants and helping to reduce long-term, overall healthcare costs.”
Improved alloys with greater mechanical properties and a longer life are the good news. The bad news is their cost and availability. Demand-supply concerns have resulted in cobalt-chrome alloys costing 35% more today than they did in 2003, and titanium prices are up more than 55% for the same period. In addition, titanium lead times can stretch beyond a year, and zircon sand is in stockpiling mode. Experts expect some supply pressures to ease once new suppliers in India, South Africa and other countries come online within the next decade.
Six Trends for 2006
The service side of orthopedic casting has also evolved over the past few years. “Innovation in the orthopedic implant market is not just coming from manufacturing techniques, but also from service delivery and supply chain solutions that offer OEMs end-to-end concepts,” Lewis explained.
Six paradigms are expected to play a more pervasive role in the industry in the coming year:
• Earlier involvement will become more commonplace. More frequently than in the past, OEMs are coming to casting houses. Singh believes earlier collaboration between OEMs or their consultants and casting houses is necessary to improve product quality and reduce costs and time. “Some of the larger OEMs have their own foundries, so they possibly may have more interaction between the foundries and their design engineers. But most independent suppliers at this point don’t seem to have an optimal level of involvement from OEM design engineers,” Singh said. “We should encourage more exchange of ideas between design engineers and the people who produce the products because everyone will benefit—OEMs, foundries, casting houses and, most important, patients.”
• Tolerances are becoming tighter. Both in final products and in the casting process itself, OEMs are demanding ever-tighter tolerances—in some cases, to the point of “machined” tolerances at the casting level. This requirement is placing additional pressures on the casting and forging houses to provide the required product but keep costs down.
• Casting houses are expanding their offerings. Customers are asking casters to take on finishing operations they used to do and provide net shapes or semi-finished parts rather than a raw casting, Wyte noted. “Going forward, we will need to hire more people for an in-house machine shop, polishing shop and other offerings,” he said. “We’ve also had some customers asking about inventory management and supply chain management.”
A global presence is increasingly important as well. Doncasters noted that it has recently invested $3 million in its low-cost manufacturing site in Mexico to offer customers greater choice and flexibility. The Mexico facility has 25,000 square feet dedicated to orthopedic and spinal machining and finishing of both implants and instrumentation. The company also has boosted manufacturing capacity by transferring non-medical projects in its Oregon City, OR and Sheffield, UK facilities to other sites.
• Strong annual growth should persist. Casters note that their businesses grew by 10% to 25% this past year, and they forecast continued double-digit gains for the foreseeable future. Increased market demand for implants—by a population that is living longer, playing harder and increasingly more able and willing to pay for healthcare that lets them maintain an active lifestyle—and increased outsourcing of casting, even from OEMs with their own in-house operations, should fuel that growth. OEMs, experiencing their own double-digit growth, are often finding that market demand is outstripping their internal capacity.
Therefore, they are sending more work to independent foundries and casters.
• Spine castings are the uncharted territory for castings. Spine products are the fastest-growing segment of the market, and castings and forgings will be looked at to provide cost-containment opportunities.
This market is currently an untapped opportunity for casting and forging houses, remaining in the control of metal injection molding and machining houses, but that scenario is likely to change.
• OEMs must court consumers. Just as the pharmaceutical industry promotes its products directly to consumers, implant OEMs soon must deliver their product messages to patients. “Our target market is becoming much more sophisticated at selecting and identifying their wants and needs in orthopedics,” Little said. “It used to be the surgeon who controlled when and how surgery was done and what product was used. Consumers are now starting to make more of those decisions and request particular products they have seen online.”
On the other hand, S&A Consulting Group, in a study it conducted about titanium implants supply and growth in 2004, talked with dozens of patients who said they did not know what options they had.
“The industry as a whole needs to educate consumers about implant design and materials choices, what’s available and how implants can improve their life,” Singh said.
The outlook for casting looks bright for years to come. Increased use of computer controls, improved alloys and streamlined business processes have combined to allow OEMs to create implants with tighter tolerances, lighter weight and greater longevity—in short, improving life for everybody.