DePuy Spine has worked and partnered with leading clinicians and researchers for over 20 years to advance the knowledge of both professionals and patients in spinal pathologies and to develop products to treat spine disorders. The company makes over 70 products with tens of thousands of product codes that are distributed globally from the US, UK and Switzerland.

In the first year of using its M 270 DMLS machine, DePuy processed 2,000 prototype parts including benders, extractors, surgical screws, clamps and reduction devices. According to staff team leader Peter Ostiguy, delivery times for surgical tool prototypes have shrunk from several months to less than a week in some cases.

Image courtesy of DePuy Spine
Prototype plate bender, used to contour plates for spinal surgery, built by DePuy in the EOSINT M270 laser-sintering system.

He comments, “Laser-sintering is very well suited to our environment because we need to produce our products quickly. We’ve really impressed surgeons with our ability to turn around what they’re looking for in a short amount of time.”

Those surgeons’ opinions are important, as some of them are active consultants to DePuy throughout the product development process.

EOSINT M270 DMLS machine. De Puy Spine processed 2,000 prototype parts of surgical equipment and devices on this type of machine in the first year of use alone.

“We work with the thought-leaders in the industry, many of whom tour our rapid prototyping lab every year, as do other surgeons not on the project teams,” continues Ostiguy.

“What has cut development time so dramatically lately is the capability of the M 270 to build multiple iterations of an instrument prototype in a matter of days.”

The DePuy development team starts with a basic design idea, often making a plastic prototype first on a different machine in their shop, and shows it to the surgeons for feedback. After modifying the design according to input from the medical profession, DePuy turns to the M 270 to create a metal prototype, if the application is appropriate.

The DMLS process begins with a CAD model of the product, which is cross-sectioned horizontally into thin layers. A first layer of 17-4 stainless steel powder is deposited at a thickness of 20µm onto a platform in the machine’s work chamber. The layer is then sintered by a focused laser beam. The work platform is lowered and the process is repeated additively, layer by layer, until a three-dimensional metal part is produced.

In this way, extremely complex geometries are created automatically, directly from CAD data, in just a few hours. Maximum dimensions are 250 mm x 250 mm x 215 mm high.

“What’s nice about this technique is that we can easily make multiple iterations of a tool to give our doctors more choice,” says Ostiguy.

“In many instances, we used to have to go with just one iteration, but now we have greater flexibility to present more options. When assessing an instrument, there’s no substitute for actually holding it.”

“The consulting doctors can be very exacting about their requirements for tools such as blades, racks, tweezers, and calipers. When they review the parts, they may ask for different handle angles or different spring strengths,” says Ostiguy.

“It’s very easy to adjust the CAD design and make another iteration. Laser-sintering lets us make virtually anything they ask for.”

The result of introducing laser-sintering into DePuy’s development centre has been a paradigm shift in the thought process for designing tools, according to Ostiguy. He says that they are not designing for manufacturability any more, but for functionality. Previously, during the design process they were constantly thinking about how they were going to make the part within process limits. With laser-sintering, that no longer matters.

Once the consulting doctors are satisfied with an instrument design, DePuy quickly makes a final metal prototype in the M 270 and sets up a cadaver section so the surgeons can put the item through its paces. Cadaver testing of metal prototypes is the last stage in product development before DePuy sends the 3D model file for the approved piece to an outside company for manufacturing. The finished items undergo a last round of mechanical testing and verification before being used in actual surgery.

Unlike prototypes tested in cadavers, instruments for in vivo surgical use must be made from materials that are biocompatible with the human body. Due to their success with DMLS for prototyping, DePuy recently purchased another M 270 for manufacture.

“If we can make products on our own machine, we can save time and money and be even more responsive to our doctors’ requirements,” says Ostiguy.

The second M 270 machine will be dedicated to a single, heat-treatable material, EOS Stainless Steel PH1 (precipitation hardening stainless steel), which is characterized by high hardness, strength and corrosion resistance. PH1 can be machined, spark-eroded, welded, micro shot-peened, polished and coated if required.

The new M 270 is programmable to run layers of either 20 or 40 microns (a thicker layer cuts down on run time, a thinner one provides finer detail) and can process multiple materials as well. Although his group is concentrating on laser-sintering PH1 material for now, Ostiguy says that the possibilities are endless for future product development.

About EOS

EOS was founded in 1989 and is today the world’s leading manufacturer of laser-sintering systems. Laser-sintering is the key technology for e-Manufacturing, the fast, flexible and cost-effective production of products, patterns or tools. The technology manufactures parts for every phase of the product life cycle, directly from electronic data. Laser-sintering accelerates product development and optimizes production processes. EOS completed its business year 2006/2007 with revenues in laser-sintering of 59.7 million Euro, which is an increase of 14 percent over the previous year. The company employs more than 250 people worldwide, more than 200 of them at its headquarters in Krailling near Munich, Germany.

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