3D printer
What is 3D printing
3D printing or additive
manufacturing is a process of making three dimensional solid objects from a
digital file. The creation of a 3D printed object is achieved using additive
processes. In an additive process an object is created by laying down
successive layers of material until the entire object is created. Each of these
layers can be seen as a thinly sliced horizontal cross-section of the eventual
object.
How it works
It all starts with making a virtual
design of the object you want to create. This virtual design is made in a CAD
(Computer Aided Design) file using a 3D modeling program (for the creation of a
totally new object) ór with the use of a 3D scanner (to copy an existing
object). This scanner makes a 3D digital copy of an object and puts it into a
3D modeling program.
To prepare the digital file created
in a 3D modeling program for printing, the software slices the final model into
hundreds or thousands of horizontal layers. When this prepared file is uploaded
in the 3D printer, the printer creates the object layer by layer. The 3D
printer reads every slice (or 2D image) and proceeds to create the object
blending each layer together with no sign of the layering visible, resulting in
one three dimensional object.
Methods and technologies
Not all 3D printers use the same
technology to realize their objects. There are several ways to do it and all
those available as of 2012 were additive, differing mainly in the way layers
are build to create the final object. Some methods use melting or softening
material to produce the layers. Selective laser sintering (SLS) and fused
deposition modeling (FDM) are the most common technologies using this way of
printing. Another method of printing is to lay liquid materials that are cured
with different technologies. The most common technology using this method is
called stereolithography (SLA).
Selective laser sintering (SLS)
This technology uses a high power
laser to fuse small particles of plastic, metal, ceramic or glass powders into
a mass that has the desired three dimensional shape. The laser selectively
fuses the powdered material by scanning the cross-sections (or layers)
generated by the 3D modeling program on the surface of a powder bed. After each
cross-section is scanned, the powder bed is lowered by one layer thickness.
Then a new layer of material is applied on top and the process is repeated
until the object is completed.
All untouched powder remains as it
is and becomes a support structure for the object. Therefore there is no need
for any support structure which is an advantage over SLS and SLA. All unused
powder can be used for the next printing. SLS was developed and patented by Dr.
Carl Deckard at the University of Texas in the mid 1980s, under sponsorship of
DARPA.
Fused deposition modeling (FDM)
The FDM technology works using a
plastic filament or metal wire which is unwound from a coil and supplies
material to an extrusion nozzle which can turn the flow on and off. The nozzle
is heated to melt the material and can be moved in both horizontal and vertical
directions by a numerically controlled mechanism, directly controlled by a
computer-aided manufacturing (CAM) software package. The object is produced by
extruding melted material to form layers as the material hardens immediately
after extrusion from the nozzle.
FDM was invented by Scott Crump in
the late 80’s. After patenting this technology he started the company Stratasys
in 1988. The software that comes with this technology automatically generates
support structures if required. The machine dispenses two materials, one for
the model and one form a disposable support structure.
The term fused deposition modeling
and its abbreviation to FDM are trademarked by Stratasys Inc. The exactly
equivalent term, fused filament fabrication (FFF), was coined by the members of
the RepRap project to give a phrase that would be legally unconstrained in its
use.
Stereolithography (SLA)
The main technology in which
photopolymerization is used to produce a solid part from a liquid is SLA. This
technology employs a vat of liquid ultraviolet curable photopolymer resin and
an ultraviolet laser to build the object’s layers one at a time. For each
layer, the laser beam traces a cross-section of the part pattern on the surface
of the liquid resin. Exposure to the ultraviolet laser light cures and
solidifies the pattern traced on the resin and joins it to the layer below.
After the pattern has been traced,
the SLA’s elevator platform descends by a distance equal to the thickness of a
single layer, typically 0.05 mm to 0.15 mm (0.002″ to 0.006″). Then, a
resin-filled blade sweeps across the cross section of the part, re-coating it
with fresh material. On this new liquid surface, the subsequent layer pattern
is traced, joining the previous layer. The complete three dimensional object is
formed by this project. Stereolithography requires the use of supporting
structures which serve to attach the part to the elevator platform.
Applications
Applications include design
visualization, prototyping/CAD, metal casting, architecture, education,
geospatial, healthcare and entertainment/retail.
Other applications would include
reconstructing fossils in paleontology, replicating ancient and priceless
artifacts in archaeology, reconstructing bones and body parts in forensic
pathology and reconstructing heavily damaged evidence acquired from crime scene
investigations.
In 2007 the use of 3D printing
technology for artistic expression was suggested. Artists have been using 3D
printers in various ways.
As of 2010 3D printing technology
was being studied by biotechnology firms and academia for possible use in
tissue engineering applications where organs and body parts are built using
inkjet techniques. Layers of living cells are deposited onto a gel medium and
slowly built up to form three dimensional structures. Several terms have been
used to refer to this field of research like: organ printing, bio-printing, and
computer-aided tissue engineering.
Industrial printing
In the last couple of years the term
3D printing has become more known and the technology has reached a broader
public. Still most people haven’t even heard of the term, while the technology
has been in use for decades. Especially manufacturers have long used these
printers in their design process to create prototypes for traditional
manufacturing and research purposes. Using 3D printers for these purposes is
called rapid prototyping.
Why use 3D printers in this process
you might ask yourself. Now, fast 3D printers can be had for tens of thousands
of dollars and end up saving the companies many times that amount of money in
the prototyping process. For example, Nike uses 3D printers to create
multi-colored prototypes of shoes. They used to spend thousands of dollars on a
prototype and wait weeks for it. Now, the cost is only in the hundreds of
dollars, and changes can be made instantly on the computer and the prototype
reprinted on the same day.
Besides rapid prototyping, 3D
printing is also used for rapid manufacturing. Rapid manufacturing is a new
method of manufacturing where companies are using 3D printers for short run
custom manufacturing. In this way of manufacturing the printed objects are not
prototypes but the actual end user product. Here you can expect more
availability of personally customized products.
Personal printing
Personal 3D printing or domestic 3D
printing is mainly for hobbyists and enthusiasts and really started growing in
2011. Because of rapid development within this new market printers are getting
cheaper and cheaper, with prices typically in the range of $250 – $2,500. This
puts 3D printers into more and more hands.
The RepRap open source project
really ignited this hobbyist market. For about a thousand dollars people have
been able to buy the RepRap kit and put together their own personal 3D printer,
complete with any customizations they were capable of making. What really
speeds the development is the open source idea. Everybody working on the RepRap
shares their knowledge so other people can use it and improve it again.
This rapid development of open
source 3D printers is gaining interest in both the developed as well as the
developing world and it enables both hyper-customization and the use of designs
in the public domain to fabricate open source appropriate technology through
conduits such as Thingiverse and Cubify. This technology can also assist
insustainable development as such technologies are easily and economically made
from readily available resources by local communities to meet their needs.
Services
Not everybody can afford or is
willing to buy their own 3D printer. Does this mean you cannot enjoy the
possibilities of 3D printing? No, not to worry. There are 3D printing service
bureaus like Shapeways and Ponoko that can very inexpensively print and deliver
an object from a digital file that you simply upload to their user-friendly
website. You can even sell your 3D designs on their website and make a little
money out of it!
If you don’t design your own 3D
models, you can still print some very nice objects. There are model
repositories such as Thingiverse, 3D Warehouse and 3D Parts Database that have
model files you can download for free.
There are also companies who offer
their services business-to-business. When, for instance, you have an
architecture practice and you need to build model scales it is very time
consuming doing this the old fashion way. There are services where you can send
your digital model and they print the building on scale for you to use in
client presentations. These kind of services can already be found in a lot of
different industries like dental, medical, entertainment and art.
History
In the history of manufacturing,
subtractive methods have often come first. The province of machining
(generating exact shapes with high precision) was generally a subtractive
affair, from filing and turning through milling and grinding.
Additive manufacturing’s earliest
applications have been on the toolroom end of the manufacturing spectrum. For
example, rapid prototyping was one of the earliest additive variants and its
mission was to reduce the lead time and cost of developing prototypes of new
parts and devices, which was earlier only done with subtractive toolroom
methods (typically slowly and expensively). However, as the years go by and
technology continually advances, additive methods are moving ever further into
the production end of manufacturing. Parts that formerly were the sole province
of subtractive methods can now in some cases be made more profitably via
additive ones.
However, the real integration of the
newer additive technologies into commercial production is essentially a matter
of complementing subtractive methods rather than displacing them entirely.
Predictions for the future of commercial manufacturing, starting from today’s
already- begun infancy period, are that manufacturing firms will need to be
flexible, ever-improving users of all available technologies in order to remain
competitive.
Future
It is predicted by some additive
manufacturing advocates that this technological development will change the
nature of commerce, because end users will be able to do much of their own
manufacturing rather than engaging in trade to buy products from other people
and corporations.
3D printers capable of outputting in
colour and multiple materials already exist and will continue to improve to a
point where functional products will be able to be output. With effects on energy
use, waste reduction, customization, product availability, medicine, art,
construction and sciences, 3D printing will change the manufacturing world as
we know it.
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