Biomedical Engineering Reference
In-Depth Information
surgeons, computer specialists and biomechanical engineers. An alternative tech-
nique is provided by selective laser melting (SLM).
3
Manufacturing of personalized prostheses as just discussed is the result of world-
wide intense research programs. Referred to here is an example of a real case and a
real custom-made device. The direct and indirect prehistory of the triflange acetab-
ular cup can be found in papers by Gelaude, all containing an extended list of
bibliographic references relevant to the subject [
249
-
252
].
The philosophy for rapid manufacturing always starts from a digitized model,
one example was briefly discussed above. In the following sections, the technology
of four different techniques will briefly be commented and illustrated with a few rep-
resentative examples. The heart of the techniques is always a focused beam, either
an electron or a laser beam, melting metal or ceramic powder or polymer powder,
or polymerizing (and solidifying) liquid mono- or oligomers. The volume of the
heated zone is constrained to micrometer-sized diameter and depth. Needed are (1)
a digitalized size and shape of the device that has to be manufactured, (2) software
that slices the digitalized device in thin
-slices, and (3) a scanning focused beam
(photons or electrons) that is copying and drawing the details of one
xy
xy
-slice on the
plane of the
Build
cylinder (covered by powder or by a liquid).
The advantages of all four techniques are:
Unlimited geometric freedom.
No tooling or set-up costs; cost-effective production of unique implants, instru-
ments or small series.
Fully digital production.
Use of biocompatible alloys.
Integration of osteoconductive structures.
Patient-specific implant design, validation and production.
7.2
Electron Beam Melting
Machine Layout
Rapid Manufacturing of metal objects of any shape can be realized by use of Elec-
tron Beam Melting. Electrons are generated in the electron beam gun, accelerated
(
Anod
) and electromagnetically focused (
Fo c u s c o i l
as shown in Fig.
7.3
).
4
Powder
is spread over the
Building Table
and the electron beam melts a thin layer of metal
powder, copying successively the slices of the digitalized object to be manufactured.
3
LayerWise is one of the companies using SLM, located at Kapeldreef 60, BE-3001 Leuven,
Belgium.
E-mail:
info@layerwise.com.
Managing
director:
Peter
Mercelis,
email:
Peter.
Mercelis@layerwise.com.
4
The machine
Arcam A
2 is produced by Arcam AB Krokslatts Fabriker 27A, 431 37 MLNDAL,
Sweden.Website: www.arcam.com.
