3D printers
Last updated: January 27, 2010.
Even the best artists struggle to show us what real-world objects
look like in all their three-dimensional (3D) glory. Most of the time
that doesn't matter—looking at a photo or sketch gives us a
good-enough idea. But if you're in the business of developing new
products and you need to show them off to clients or customers,
nothing beats having a prototype: a model you can touch, hold, and
feel. Only trouble is, models take ages to make by hand and
machines that can make "rapid prototypes" cost a fortune (up to a
half million dollars). Hurrah, then for 3D printers, which work a bit
like inkjets and build up 3D models layer by layer at up to 10 times
the speed and a fifth the cost. How exactly do they work? Let's take
a closer look!
Photo: A typical 3D printer. This one is a Z Corporation ZPrinter® 450.
Photo by Tom Taylor published on
Flickr in 2009
under a Creative Commons Licence.
From hand-made prototypes to rapid prototyping
Before there were such things as computer-aided design (CAD) and
lasers, models and prototypes were laboriously carved from wood or
stuck together from little pieces of card or plastic. They could take
days or even weeks to make and typically cost a fortune. Getting
changes or alterations made was difficult and time-consuming,
especially if an outside model-making company was being used, and
that could discourage designers from making improvements or taking
last-minute comments onboard: "It's too late!"
With the arrival of better technology,
an idea called rapid prototyping (RP) grew up during the 1980s
as a solution to this problem: it means developing models and
prototypes by more automated methods, usually in hours or days rather
than the weeks that traditional prototyping used to take. 3D printing
is a logical extension of this idea in which product designers make
their own rapid prototypes, in hours, using sophisticated machines
similar to inkjet printers.
Photo: A high-quality rapid prototype of a space plane made in wax
from a CAD drawing by NASA. Photo courtesy of
NASA Langley Research Center (NASA-LaRC).
How does a 3D printer work?
Imagine building a conventional wooden prototype of a car. You'd
start off with a block of solid wood and carve inward, like a
sculptor, gradually revealing the object "hidden" inside. Or if
you wanted to make an architect's model of a house, you'd construct
it like a real, prefabricated house, probably by cutting miniature
replicas of the walls out of card and gluing them together. Now a
laser could easily carve wood into shape and it's not beyond the
realms of possibility to train a robot to stick cardboard
together—but 3D printers don't work in either of these ways!
A typical 3D printer is very much like an inkjet printer operated
from a computer. It builds up a 3D model one layer at a time, from
the bottom upward, by repeatedly printing over the same area. Working entirely automatically, the printer creates a model
over a period of hours by turning a 3D CAD
drawing into lots of two-dimensional, cross-sectional
layers—effectively separate 2D prints that sit one on top of
another, but without the paper in between. Instead of using ink, which would never build up to much
volume, the printer deposits layers of molten plastic or powder and
fuses them together (and to the existing structure) with adhesive or ultraviolet light.
Photo: A computer-aided-design (CAD) drawing
like this is the starting point for a 3D print.
Photo courtesy of NASA Glenn Research Center (NASA-GRC).
Advantages and disadvantages
Makers of 3D printers claim they are up to 10 times faster than
other methods and 5 times cheaper, so they offer big advantages for
people who need rapid prototypes in hours rather than days. Although
they are still expensive (typically about $25,000 -$50,000), they're
a fraction the cost of more sophisticated RP machines (which come in
at $100,000-$500,000), and cheaper machines are now beginning to
appear. They're also reasonably small, safe, easy-to-use, and
reliable (features that have made them increasingly popular in places such as
design/engineering schools).
On the downside, the finish of the models they produce is usually
inferior to those produced with higher-end RP machines. The choice of
materials is often limited to just one or two, the colors may be crude,
and the texture may not reflect the intended finish of the product very well. Generally, then, 3D-printed models
may be better for rough, early visualizations of new products; more
sophisticated RP machines can be used later in the process when
designs are closer to finalization and things like accurate surface
texture are more important.
Photo: Quick, simple, cheap, effective: a 3D-printed model gives a good general
impression, even if it's not necessarily faithful in detail, color, or finish.
Photo by Tom Taylor published on
Flickr in 2009
under a Creative Commons Licence.
Further information
Manufacturers
