EBM machines for medical applications. He also pointed out that the advantage these manufacturers were looking for is in making trabecular structures. Tese are fine, interlaced, sometimes-spongy looking bone or artificial lattices. Tey give structures lightness combined with strength. Tey also provide an ability to fuse living bone into the implant, called osseointegration. Arcam provides the ability to specify in the design of the implant pore geometry, pore size, relative den- sity, and roughness for these structures or surfaces. Manufacturers like to have machines tuned for their
industry. Tis is no different for medical. René pointed out this means easy FDA or CE Mark approval as one factor. Te Arcam A1 EBM system was specifically designed for the orthopedic implant industry. It boasts high productivity to create either custom or standard implants. Materials include cobalt chrome and titanium alloys. It has a beam power of up to 3000 watts in its vacuum build chamber, with active cool- ing for shorter build cycles. Its MultiBeam technology allows for faster builds and model-to-part accuracy of ± 0.13 mm, providing a surface finish specification of 25 Ra direction and 35 Ra
cm3 /hr using Ti6Al4V titanium alloy. “Te real winner is design freedom when using additive
manufacturing,” said René of Arcam. “Te value of AM is not in converting an existing process, but developing a design tuned for the process.”
Prosthetics Too ExOne (North Huntingdon, PA) is another additive manu-
facturing company with a beachhead in the medical field. Unlike laser sintering or EBM that melt powders of metal or plastic, ExOne uses binder-jetting technology. “We selec- tively print a binder into a powder bed, essentially gluing the particles together,” explained Robert Wood, regional manager for ExOne. Te advantage of this process is the wider range of materials possible. “If you can get the material into a powder form suitable for our process, we can print it,” he said. One advantage of this process over selective melting processes is that the loose powder is not disturbed, eliminating the need to design elaborate supporting structures, according to Wood. Te downside is that there is a sintering post-process re- quired—up to 1100°C—before the part is ready for use. “Still, our process can be significantly less expensive than other methods, such as laser,” he said. “Tat is due to the speed and output of our machine, our layer speeds are much faster. Our build envelopes are much bigger so we are able to produce a lot more parts in one print.” Wood reports that his company also is in medical produc-
tion, delivering, for example, finger structures for a prosthetic hand. Each finger structure is composed of 60% 420 stain- less steel infiltrated with 40% bronze. “In our process, the green finger structure before sintering is about 60% density,”
explained Wood. “When we sinter it, we get the density up to about 90% and to prevent warpage and cracking, we infiltrate it with bronze.” Te company reports that their process re- placed an existing investment casting procedure and is about ten times less expensive. Wood also reported that they also use the process to generate tooling for medical parts, such as molds for casting or injection molding.
The Future—Education, Materials, Data Integration Te future of these additive processes in medical manu-
in the vertical in horizontal. Its build rate is as high as 80
facturing hinges on two factors, according to Wood. One is educating the industry on the power and limitations of additive technologies. Te other is materials. “For direct production, binder jet technology opens up the possibility of using new materials, such as ceramics,” he predicted, even bioabsorbables. Wohlers, the consultant, also sees a future in 3D printing for living tissues using resorbable or biodegrad- able scaffolding structures. “Tey could use, for example, hydroxylapatite that your body accepts, and can break down,” said Wohlers. “Tere has been a lot of work in this area over the last 10 years.”
The EBM process is a cost-effective tool for high- volume manufacturing of orthopedic implants.
Renishaw (Hoffman Estates, IL), long known as a provider
of metrology technology, is another provider of additive manufacturing systems. Robin Weston, global product man- ager for Renishaw in this area, sees a future in information integration. Renishaw has a number of health technologies, including surgical planning soſtware, implantable therapeutic delivery devices, and stereotactic surgical robots. “Our disci- plines are founded on our metrology capability and our ability to control processes,” explained Weston. “What you will see is us integrating the expertise in those areas and marry that up to the additive manufacturing technology.” He believes provid- ing a more complete solution, rather than selling machines with which organizations can experiment, will be the future as the industry matures.