Collaboration transforms medtech manufacturing

Held in the orthopedic capital of the world – Warsaw, Indiana – GF Machining Solutions, OPEN MIND Technologies, Seco Tools, Zeiss Industrial Quality Solutions, and DLyte offered a seminar on innovative technologies to address many of the various challenges faced when producing quality orthopedic implants. The aim of Efficient Manufacturing of Orthopedic Implants was to deliver insights into improving manufacturing efficiency by understanding and addressing process stability, automated production, the influence machine design has on device quality, tool design, polishing, and automated inspection.

The event was the brainchild of GF Machining Solutions’ Medical Market Segment Manager Erik Poulsen. After a keynote presentation by Ali Madani, managing partner with Avicenne, who highlighted how the average market price for knee or hip implants is dropping around 2% a year with a 5% to 7% growth rate in the market and an 8% increase in orthopedic products manufacturers must get out the door, Poulsen explained how this group event began.

The knee implant marketplace is large; about 4 million total knee implants every year. The market pressure on prices means there’s pressure on finding more efficiencies in manufacturing, and the complex shape and dimensional precision required to make a good knee implant is perhaps the greatest challenge in manufacturing.

“The average lifespan of a knee implant is directly related to the quality of components that go in, and the marriage between the condyle surfaces. If quality is poor, the knee and liner may only contact on a single point. If there’s a sharp edge on the knee where it contacts the liner, it’s going to wear the liner prematurely and that’s not good for anyone,” Poulsen noted. “So, in general, castings are the starting point for knee implants, and these castings tend to be machined through a milling process, sometimes also by a 5-axis grinding process. Following the machining steps, you’re typically going to go into a three-step polishing process which starts with a drag finish through ceramic media, then generally into plastic media, sometimes also into nutshell or other types of final polish media for the final finish. A GF customer asked if we could find a way to go directly from milling to a two-step polishing process – to eliminate drag finishing.”

To address that customer’s inquiry, the participants detailed their best-practices approach.

Start with the machine

There are different sources of error in the manufacturing process that can result in all the problems the event aimed to address. Poulsen noted, “the CAM program might not be optimized. You might have substandard cutting tools generating errors. You can also have a machine itself creating errors in position or in toolpath and this drift can cause mismatched curves on the condyle or can cause shadows to occur. It can also cause the blend on the patella area to be ‘staircased’ instead of smooth.”

For a starting point, the machine design should include linear motors to prevent backlash from creeping into the process. Additional machine considerations are polymer concrete bases which enable intelligent thermal compensation as well as improved vibration dampening. Finally, Poulsen notes, you want an optimized milling machine capable of having strength but moving quickly. GF Machining Solutions delivers this by using welded steel elements for key parts that are both light and rigid, so the machine runs fast and absorbs machining forces.

Another area Poulsen mentioned was GF Machining Solutions’ work in CO2 milling of titanium and how it achieves reliable machining with higher material removal rates, significantly increased tool life, significantly lower cutting forces, increased surface micro hardness, reduced surface roughness, and a cleaner product exiting the milling process.

Software, tooling matters

Following Poulsen’s presentation was Chris Gamble, an OPEN MIND Technologies account manager, who explained how hyperMILL supports precision orthopedic production. Using a CAM software with a function such as smooth overlap will eliminate irregularities. By having the software feather blend the image on the computer using OPEN MIND’s algorithm, it adds a slight uplifting to the surface path where the transitions occur, eliminating visible stairstep machining errors on the implant and improving surface finish.

Dominic Connor, application engineer with Seco Tools, presented the importance of cutting tool design and cutting tool geometry for medical implant success. “You need to understand the part you’re cutting and what tool you need for coatings, wiper geometries, negative rake angles, and more. The tool must fit the part being machined, and you need to match that tool to the feature being produced.”

Wrapping up the first set of sessions was Luis Hernandez, technical sales engineer with ZEISS Industrial Quality Solutions. Fast, accurate validation of complex implant parts is a must as the market expands, and scanning technologies from ZEISS can help inspect and validate the complex dimensions of implants. Additionally, as more implants are produced as one-off, customized for the patient, individual inspection of each part is required throughout the manufacturing process – not just a number from a batch of many.

“This is where the right partner for quality assurance can look at the process and determine the best solution for the process, such as computed tomography (CT), confocal white light sensors for measurement of depth, optical 3D scanning, etc., with the goal being quality assurance via a feedback loop into manufacturing, making sure what the manufacturer is trying to achieve is what we’re working toward with them implementing the right QA process,” Hernandez explained.

While the group of sessions went into more detail from the companies that presented in the first half, finishing out the event was a presentation from DLyte’s Chief Operating Officer Patrick Sage, covering polishing and surface finishing technology for medical implants. DLyte series machines, based on Drylyte technology for surface finishing metal alloys, focus on automation, simplification, and standardization. Applications include grinding, deburring, surface smoothing, and high-gloss polishing. A dry electropolishing system selectively removes a thin layer of material from a metal part to achieve shine, smoothness, and ultra-clean surfaces. The process can polish and deburr fragile parts with complex geometric forms. Using a soft, non-abrasive polish medium avoids damaging round part edges. Suitable materials for the machine include cobalt chrome, stainless steel, titanium, and Nitinol.

Takeaways

Attendees were orthopedic implant manufacturers facing the challenge of producing more implants, faster, and often while facing a lack of skilled workers. The overarching theme was highlighting today’s technology and how to find those partners that work together – from the machine to the software, cutting tools, inspection, and finishing – for an approach that can deliver high-quality products demanded by not just the surgeons, but the patients as well.

DLyte
https://www.dlyte.com

GF Machining Solutions
https://www.gfms.com

OPEN MIND Technologies
https://www.openmind-tech.com

Seco Tools
https://www.secotools.com

ZEISS Industrial Quality Solutions
https://www.zeiss.com/metrology

About the author: Elizabeth Engler Modic is editorial director for GIE Media’s Manufacturing Group. She can be reached at 216.303.0264 or EModic@gie.net.