Biomedical Engineering Reference
In-Depth Information
Table 2.1 Definitions of AM process categories in accordance with the ASTM
International Committee F42 on Additive Manufacturing Technologies
(2010).
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Category
ASTM definition
Vat photopolymerisation
An additive manufacturing process in which liquid
photopolymer in a vat is selectively cured by light-
activated polymerisation
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Material jetting
An additive manufacturing process in which droplets of
build material are selectively deposited
Binder jetting
An additive manufacturing process in which a liquid
bonding agent is selectively deposited to join powder
materials
Material extrusion
An additive manufacturing process in which material is
selectively dispensed through a nozzle or orifice
Powder bed fusion
An additive manufacturing process in which thermal
energy selectively fuses regions of a powder bed
Sheet lamination
An additive manufacturing process in which sheets of
material are bonded to form an object
Direct energy deposition
An additive manufacturing process in which focused
thermal energy is used to fuse materials by melting as
they are being deposited
however, there has been particular interest for AM in aerospace and bio-
medical industries owing to the possibility for high performance parts.
32,34
For biomedical applications, AM offers a closed process chain. For example,
bone replacement materials can be fabricated by scanning the bone defect
using magnetic resonance imaging (MRI) or computer tomography (CT), de-
signing the implant structure, then directly manufacturing the individual
implant. This closed process chain will have the potential to offer custom-
fitting implants to the damaged part's anatomy.
35
Also the freedom of design
offered by this technology will enable the fabrication of complex geometries of
the implants, in terms of both external and internal morphology.
.
2.2.1 Selective Laser Melting
Selective laser melting (SLM) is an AM technique capable of fabricating
metallic parts. Being an AM technique, increased geometrical freedom
allows the fabrication of a part as envisioned without the manufacturing
constraints prevailed with conventional techniques such as CNC ma-
chining, moulding and casting. Gold, stainless steel (316L and 17-4PH),
tool steel, commercially pure titanium and its alloys (Ti6Al4V, Ti6Al7Nb
and Ti24Nb4Zr8Sn), aluminium AlSi12, cobalt-chrome (ASTM) and Inconel
718 and 625 are some of the powdered materials that can be processed
currently using SLM.
36-42
SLM has been identified as a route to fabricate
parts with a high material utilisation rate without using expensive moulds/
forgings.
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