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 object is created. Each of these
layers can be seen as a thinly sliced horizontal cross-section of the
eventual object.
How does 3D printing work?
It all starts with making a virtual design of the object you want to
create. This virtual design is for instance a CAD (Computer Aided
Design) file. This CAD file is created using a 3D modeling application
or with a 3D scanner (to copy an existing object). A 3D scanner can make
a 3D digital copy of an object.
3D scanners
3D scanners use different technologies to generate a 3D model. Examples
are: time-of-flight, structured / modulated light, volumetric scanning
and many more.
Recently, companies like Microsoft and Google enabled their hardware
to perform 3D scanning, for example Microsoft’s Kinect. In the near
future digitising real objects into 3D models will become as easy as
taking a picture. Future versions of smartphones will probably have
integrated 3D scanners.
Currently, prices of 3D scanners range from expensive professional industrial devices to
$30 DIY scanners anyone can make at home.
3D modeling software
3D modeling software also comes in many forms. There’s industrial grade
software that costs thousands a year per license, but also free open
source software, like
Blender, for instance. You can find some beginner video tutorials on our
Blender tutorials page.
When you are a beginner and the amount of choices are a bit overwhelming, we recommend to start with
Tinkercad.
Tinkercad has a free version and it works in browsers that support
WebGL, for instance Google Chrome. They offer beginner lessons and has a
built in option to get your object printed via various 3D printing
services.
When you have a 3D model, the next step is to prepare it in order to make it 3D printable.
From 3D model to 3D printer
You will have to prepare a 3D model before it is ready to be 3D
printed. This is what they call slicing. Slicing is dividing a 3D model
into hundreds or thousands of horizontal layers and needs to be done
with software.
Sometimes a 3D model can be sliced from within a 3D modeling software
application. It is also possible that you are forced to use a certain
slicing tool for a certain 3D printer.
When the 3D model is sliced, you are ready to feed it to your 3D
printer. This can be done via USB, SD or wifi. It really depends on what
brand and type 3D Printer you have.
When a file is uploaded in a 3D printer, the object is ready to be 3D printed
layer by layer. The 3D printer reads every slice (2D image) and creates a three dimensional object.
Learn how to 3D print
You could start your journey in learning 3D printing by following
this Coursera course. It costs around $350 USD.
For the same price however you can choose to assemble your own 3D
Printer kit. This way you’ll gradually learn al the keywords which will
help you repairing / adjusting your 3D printer when necessary.
If you are interested in going this route, please read our article about
cheap 3D printer kits. This article explains what to look for when you’re comparing these kits.
Processes and technologies
Not all 3D printers use the same technology. There are several ways
to print and all those available are 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 3D printing. Another
method is when we talk about curing a photo-reactive resin with a UV
laser or another similar power source one layer at a time. The most
common technology using this method is called stereolithography (SLA).
To be more precise: since 2010, the
American Society for Testing and Materials (ASTM) group “
ASTM F42 – Additive Manufacturing”, developed a set of standards that classify the Additive Manufacturing processes into
7 categories according to
Standard Terminology for Additive Manufacturing Technologies. These seven processes are:
- Vat Photopolymerisation
- Material Jetting
- Binder Jetting
- Material Extrusion
- Powder Bed Fusion
- Sheet Lamination
- Directed Energy Deposition
Below you’ll find a short explanation of all of seven processes for 3D printing:
Vat Photopolymerisation
A 3D printer based on the Vat Photopolymerisation method has a
container filled with photopolymer resin which is then hardened with a
UV light source.
Vat photopolymerisation schematics. Image source: lboro.ac.uk
The most commonly used technology in this processes is
Stereolithography (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 and to hold the object because it floats in the basin
filled with liquid resin. These are removed manually after the object is
finished.
This technique was invented in 1986 by Charles Hull, who also at the time founded the company, 3D Systems.
Other technologies using Vat Photopolymerisation are the new ultrafast
Continuous Liquid Interface Production or
CLIP and marginally used older
Film Transfer Imaging and
Solid Ground Curing.
Material Jetting
In this process, material is applied in droplets through a small
diameter nozzle, similar to the way a common inkjet paper printer works,
but it is applied layer-by-layer to a build platform making a 3D object
and then hardened by UV light.
Material Jetting schematics. Image source: custompartnet.com
Binder Jetting
With binder jetting two materials are used: powder base material and a
liquid binder. In the build chamber, powder is spread in equal layers
and binder is applied through jet nozzles that “glue” the powder
particles in the shape of a programmed 3D object. The finished object is
“glued together” by binder remains in the container with the powder
base material. After the print is finished, the remaining powder is
cleaned off and used for 3D printing the next object. This technology
was first developed at the Massachusetts Institute of Technology in 1993
and in 1995 Z Corporation obtained an exclusive license.
The following video shows a high-end binder jetting based 3D printer,
the ExOne M-Flex. This 3D printer uses metal powder and curing after
the binding material is applied.
Material Extrusion
The most commonly used technology in this process is
Fused deposition modeling (FDM)
Fused
deposition modelling (FDM), a method of rapid prototyping: 1 – nozzle
ejecting molten material (plastic), 2 – deposited material (modelled
part), 3 – controlled movable table. Image source: Wikipedia, made by
user Zureks under CC Attribution-Share Alike 4.0 International license.
The FDM technology works using a plastic filament or metal wire which
is unwound from a coil and supplying 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. This technology is
most widely used with two plastic filament material types:
ABS (Acrylonitrile Butadiene Styrene) and
PLA (Polylactic acid) but many other materials are available ranging in properties from wood filed, conductive, flexible etc.
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 for 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.
Powder Bed Fusion
The most commonly used technology in this processes is
Selective laser sintering (SLS)
SLS
system schematic. Image source: Wikipedia from user Materialgeeza under
Creative Commons Attribution-Share Alike 3.0 Unported license
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 print. SLS was developed and patented by Dr. Carl Deckard
at the University of Texas in the mid-1980s, under sponsorship of DARPA.
Sheet Lamination
Sheet lamination involves material in sheets which is bound together
with external force. Sheets can be metal, paper or a form of polymer.
Metal sheets are welded together by ultrasonic welding in layers and
then CNC milled into a proper shape. Paper sheets can be used also, but
they are glued by adhesive glue and cut in shape by precise blades.
A leading company in this field is
Mcor Technologies.
Simplified
model of ultrasonic sheet metal 3D printing. Image source: Wikipedia
from user Mmrjf3 shared under Creative Commons Attribution 3.0 Unported
license.
Here is a video with a metal sheet 3D printer by Fabrisonic that uses additive manufacturing paired with CNC milling:
… and here is an overview of Mcor 3D printers that use standard A4 paper sheets:
Directed Energy Deposition
This process is mostly used in the high-tech metal industry and in
rapid manufacturing applications. The 3D printing apparatus is usually
attached to a multi-axis robotic arm and consists of a nozzle that
deposits metal powder or wire on a surface and an energy source (laser,
electron beam or plasma arc) that melts it, forming a solid object.
Direct Energy Deposition with metal powder and laser melting. Image source: Merlin project
Sciaky is a major tech company in this area and here is their video presentation showing electron beam additive manufacturing:
Examples & applications of 3D printing
Applications include rapid prototyping, architectural scale models
& maquettes, healthcare (3D printed prosthetics and 3D printing with
human tissue) and entertainment (e.g. movie props).
Other examples of 3D printing would include reconstructing fossils in
paleontology, replicating ancient artifacts in archaeology,
reconstructing bones and body parts in forensic pathology and
reconstructing heavily damaged evidence acquired from crime scene
investigations.
3D printing industry
The worldwide 3D printing industry is expected to grow from $3.07B in
revenue in 2013 to $12.8B by 2018, and exceed $21B in worldwide revenue
by 2020. As it evolves, 3D printing technology is destined to transform
almost every major industry and change the way we live, work, and play
in the future.
Source: Wohlers Report 2015
Medical industry
The outlook for medical use of 3D printing is evolving at an
extremely rapid pace as specialists are beginning to utilize 3D printing
in more advanced ways. Patients around the world are experiencing
improved quality of care through 3D printed implants and prosthetics
never before seen.
Bio-printing
As of the early two-thousands 3D printing technology has been studied
by biotech 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. We refer to this
field of research with the term:
bio-printing.
Aerospace & aviation industries
The growth in utilisation of 3D printing in the aerospace and
aviation industries can, for a large part, be derived from the
developments in the metal additive manufacturing sector.
NASA
for instance prints combustion chamber liners using selective laser
melting and as of march 2015 the FAA cleared GE Aviation’s first
3D printed jet engine part to fly: a laser sintered housing for a compressor inlet temperature sensor.
Automotive industry
Although the automotive industry was among the earliest adopters of
3D printing it has for decades relegated 3D printing technology to low
volume prototyping applications.
Nowadays the use of 3D printing in automotive is evolving from
relatively simple concept models for fit and finish checks and design
verification, to functional parts that are used in test vehicles,
engines, and platforms. The expectations are that 3D printing in the
automotive industry will generate a combined $1.1 billion dollars by 2019.
Industrial 3D 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 bought 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 3D 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 could buy the RepRap kit and
assemble their own desktop 3D printer. Everybody working on the RepRap
shares their knowledge so other people can use it and improve it again.
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.
If you’re interested in more future predictions regarding 3D printing, check out
The Future Of Open Fabrication.
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,
Ponoko and
Sculpteo that
can very inexpensively print and deliver an object from a digital file
that you simply upload to their website. You can even sell your 3D
designs on their website and make a little money out of it!
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 fashioned way. There are services where you can send
your digital model to 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.
3D Marketplaces
If you don’t have the skills to design your own 3D models, you can still print some very nice objects. 3D marketplaces such as
Pinshape and CGTrader contain 3D model files you can download for a small charge or for free.
So what is 3D printing?
Reddit user Flux83 made an awesome meme:
