Direct Metal Laser Sintering for Medical Applications

6 Jun 08

An article previously published by ManufactureLink looked at applications for Direct Metal Laser Sintering or DMLS for the manufacture of cost effective direct tooling which is perhaps the most well known application for DMLS. But the nature of DMLS allows designers to develop products based on the capabilities of this process. Medical device applications are one area that has benefited significantly from the Direct Metal Laser Sintering manufacturing technology.

DMLS has applications in medical device manufacturing from rapid prototyping orthopedic implants, to manufacturing customised dental implants, and manufacturing of specialised jigs, fixtures and surgical instruments directly from 3D CAD data.

Knee implants for cadaver labs

A North American medical manufacturer recognized a better way to make complex mold inserts after inspecting the detail and resolution possible from DMLS. “Other tooling applications for DMLS might include hardened steel tools and prototype die cast tooling, which has been generally ignored in North America,” says Greg Morris, Principal and COO of (Morris Technologies Inc), Cincinnati, Ohio,. “Demand, however, has us focusing on building smaller, highly complex parts from stainless and cobalt chromium alloys. They are by far the most widely requested due to their exceptional mechanical properties,” says Morris.

In a curious application, the company makes hip and knee implants for cadaver labs that are used to prove-out designs for the FDA. “Typically, these components are cast or machined out of bar stock,” says Morris. “On the horizon in the not-too-distant future is DMLS implants for live patients. DMLS allows for other possibilities, too. Next steps would be customizing implants to mate to surrounding bones and building structures conducive to bone growth, similar to Trabecular Metal.”

Another plus: DMLS lets engineers exploit inherent advantages of additive technologies. For example, layering lets engineers design in ways that traditional manufacturing methods might not allow. “Designing to the process is the real power of this technology.” Morris says. “We can build parts in DMLS that cannot be made any other way. Parts that might otherwise have been multi-part assemblies can be made as one piece. This cuts costs and boosts part quality and efficiency.”

An example of applying this technology is the design of orthopedic implants for knee and hip replacements that have a 'honey comb' or porous internal structure within to reduce weight whilst maintaining strength.

The only real design limitations that must be considered is the internal structure must not have any enclosed area. A path must be left to remove any excess powder after the laser sintering process is complete.

A material for dental applications

EOS CobaltChrome SP1 is a superalloy powder well-suited for producing dental restorations such as crowns and bridges. Its composition corresponds to type 4 CoCr dental material in the EN ISO 16744 standard. “Skin & core,” a term used in the volume rate section below, means parts are run with fully dense surfaces and porous internal structures.

This material and the DMLS process allows dental surgeons to generate a 3D model of the required implant and directly manufacture the final piece without the need for any specalised tooling, machining or involved manufacturing processes.

New Applications for DMLS

Applications for this technology are only just beginning to be fully explored by designers. But as DMLS is becoming a more mature manufacturing technology and becoming faster, more and more components will be manufactured using this technique.

Visit ManufactureLink's Direct Metal Laser Sintering category on our manufacturing directory to locate Australian manufacturers offering this technology.