Graphics Reference
In-Depth Information
academics and businessmen from Texas, in 1989. DTM was later bought up by 3D systems
in 2001.
The SLS process uses a bed of powder with material that can consist of plastic resin, metal,
ceramics or glass. A laser beam sinters (fuse) the powder at designated places according to
the CAD-drawing, when it cools it has taken on a solid form. A levelling roller prepares the
next layer of powder and the process is repeated until the object is finalized. The surround-
ing powder supports the overhanging parts of the object, so there is no need for supporting
material. An inert gas atmosphere, such as nitrogen or argon, is maintained in the build
chamber.
The processing of metals by SLS was in the beginning an indirect method (See History of
3D printing section) and produced inferior products in terms of mechanical properties com-
pared with the 3D printing metal processing methods that came after (see below).
Carl Deckard's SLS patent 5.597.589:
“Apparatus for producing parts by Selective Sinter-
ing”
expired on January 28, 2014. Carl Deckard's company DTM which owned the pat-
ent was acquired by 3D systems in 2001. The expiration of this patent has opened up the
market for 3D printer developers to pursue the SLS technique. SLS is used for producing
prototypes and increasingly end-use parts, for example in aerospace.
Direct Metal Laser Sintering (DMLS):
(Powder bed fusion)In 1994 the German com-
pany EOS invented Direct Metal Laser Sintering. The process is similar to Selective Laser
Sintering, the main invention was the bronze-nickel based metal powder that was used.
This metal powder enabled direct production of metal parts without the post-processing
which was needed earlier. In the beginning DMLS did not allow single material metals but
was restricted to alloys.
When the technology was upgraded by a switch from CO2-lasers to fiber lasers together
with tighter atmospheric controls, the use of single component metals like titanium, alu-
minum, stainless steel and cobalt chrome was enabled.
Selective Laser Melting (SLM):
(Powder bed fusion)SLM is another variation of Select-
ive Laser Sintering. In basic parts it is similar to SLS and DMLS. The main difference is
that a stronger laser was added, which melted the metal powder instead of sintering it. The
full melting of the metal enabled production of fully dense parts. Examples of companies
using SLM are Concept Laser, Realizer, SLM Solutions and Renishaw.
Electron Beam Melting (EBM):
(Powder bed fusion)EBM is similar to SLM but uses an
electron beam instead of a laser. The EBM process works in a vacuum. The company be-
hind EBM is Swedish Arcam.
