Additive manufacturing or 3D printing is a process of
making three dimensional solid objects from a digital model. 3D printing is
achieved using additive processes, where an object is created by laying down
successive layers of material. 3D printing is considered distinct from
traditional machining techniques (subtractive processes) which mostly rely on
the removal of material by methods such as cutting and drilling.
3D printing is usually performed by a materials printer
using digital technology. Since the start of the twenty-first century there has
been a large growth in the sales of these machines, and their price has dropped
The technology is used in jewellery, footwear, industrial
design, architecture, engineering and construction (AEC), automotive,
aerospace, dental and medical industries, education, geographic information
systems, civil engineering, and many other fields.
Additive manufacturing takes virtual blueprints from
computer aided design (CAD) or animation modeling software and
"slices" them into digital cross-sections for the machine to
successively use as a guideline for printing. Depending on the machine used,
material or a binding material is deposited on the build bed or platform until
material/binder layering is complete and the final 3D model has been
"printed." It is a WYSIWYG process where the virtual model and the
physical model are almost identical.
The standard data interface between CAD software and the
machines is the STL file format. An STL file approximates the shape of a part
or assembly using triangular facets. Smaller facets produce a higher quality
surface. PLY is a scanner generated input file format, and VRML (or WRL) files
are often used as input for 3D printing technologies that are able to print in
To perform a print, the machine reads the design and lays
down successive layers of liquid, powder, or sheet material to build the model
from a series of cross sections. These layers, which correspond to the virtual
cross sections from the CAD model, are joined together or automatically fused
to create the final shape. The primary advantage of this technique is its
ability to create almost any shape or geometric feature.
Printer resolution describes layer thickness and X-Y
resolution in dpi (dots per inch), or micrometres. Typical
layer thickness is around 100 micrometres (0.1 mm), although some machines such
as the Objet Connex series and 3D Systems' ProJet series can print layers as
thin as 16 micrometres. X-Y resolution is comparable to that of laser
printers. The particles (3D dots) are around 50 to 100 micrometres (0.05-0.1
mm) in diameter.
Construction of a model with contemporary methods can take
upwards from several hours to several days, depending on the method used and
the size and complexity of the model. Additive systems can typically reduce
this time to a few hours, although it varies widely depending on the type of
machine used and the size and number of models being produced simultaneously.
Traditional techniques like injection moulding can be less
expensive for manufacturing polymer products in high quantities, but additive
manufacturing can be faster, more flexible and less expensive when producing
relatively small quantities of parts. 3D printers give designers and concept
development teams the ability to produce parts and concept models using a
desktop size printer.
Though the printer-produced resolution is sufficient for
many applications, a higher-resolution can be attained by printing a slightly
oversized version of the desired object in standard resolution and then
removing material with a higher-resolution subtractive process.
Some additive manufacturing techniques are capable of using
multiple materials in the course of constructing parts. Some also utilize
supports when building. Supports are removable or dissolvable upon completion
of the print, and are used to support overhanging features during construction.
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). With technological advances in additive manufacturing,
however, and the dissemination of those advances into the business world,
additive methods are moving ever further into the production end of
manufacturing in creative and sometimes unexpected ways. Parts that were
formerly the sole province of subtractive methods can now in some cases be made
more profitably via additive ones.
Standard applications include design visualization,
prototyping/CAD, metal casting, architecture, education, geospatial, healthcare
Main article: rapid prototyping
Full color miniature face models produced on a Spectrum Z510
Industrial 3D printers have existed since the early 1980s
and have been used extensively for rapid prototyping and research purposes.
These are generally larger machines that use proprietary powdered metals,
casting media (e.g. sand), plastics or cartridges, and are used for rapid
prototyping by universities and commercial companies. Industrial 3D printers
are made by companies including 3D Systems, Objet Geometries, and Stratasys.
Advances in RP technology have introduced materials that are
appropriate for final manufacture which has in turn introduced the possibility
of directly manufacturing finished components. One advantage of 3D printing for
rapid manufacturing lies in the relatively inexpensive production of small
numbers of parts.
Rapid manufacturing is a new method of manufacturing and
many of its processes remain unproven. 3D printing is now entering the field of
rapid manufacturing and was identified as a "next level" technology
by many experts in a 2009 report. One of the most promising processes looks
to be the adaptation of laser sintering (LS), one of the better-established
rapid prototyping methods. as of 2006, however, these techniques were still
very much in their infancy, with many obstacles to be overcome before RM could
be considered a realistic manufacturing method.
Companies such as MakieLab and Kodama Studios have created
services where consumers can customize objects using simplified web based
customization software, and order the resulting items as 3D printed unique
Full color miniature face models produced on a Spectrum Z510 3D Printer.