Some time ago, we talked about our future zillions of years from
now. The experts in the field seemed to indicate mankind”s only
hope for survival was to somehow use the “Scotty, beam me up”
approach to reconstruct ourselves in another universe. This
certainly will be a formidable task, especially since we aren”t really
sure there is such a thing as another universe! It was only natural
that I was intrigued by an article in the February 2000 issue of
Discover magazine about a small step in this direction. The
article, titled “Behold, the 3-D Fax”, describes a beam-me-up
process that is now a reality, at least insofar as certain kinds of
inanimate objects are concerned. Ok, you can”t beam the
inanimate object to another universe but you can transmit it from
New York to London or to New Jersey, which, in the view of
some New Yorkers, is equally distant from “The City”. Ok again,
you can”t transmit the object itself but you can transmit a three-
dimensional replica of sorts.
My memory is a bit rusty on the details, but I remember being
quite impressed by something I saw when I worked for NACA”s
Lewis Flight Propulsion Lab in Cleveland some 40 years ago. It
was a machine that could be programmed to carve out a wooden
or possibly a plastic model of such things as an experimental
design of an airplane wing. I don”t know how the programming
was accomplished but it was not a common thing in those days.
Today, we have the next step and the subject of the Discover
article, the three-dimensional replicator (3-DR) or, as termed by
its inventor, stereolithography. Let”s stick with 3-DR.
Our hero is Charles Hull, who was working for a company that
made ultraviolet lamps used to harden special plastic coatings of
some sort. In 1984, Hull was fooling around in his lab and
decided that he could use these lamps to make solid plastic
objects. What he did first was to dump a bunch of gooey plastic
in a basin. Now he wanted to harden certain specific areas of the
plastic. So, he designed a computer system that could guide a
beam of the UV light in the desired pattern on the surface of the
plastic. This hardened a layer of the goo where the light hit the
plastic. Hull then lowered a platform just below the surface the
basin. I”m assuming that the hardened plastic stuck to the
platform. By lowering the platform just a tad, a thin layer of goo
covered the hardened layer of plastic. This process of patterned
illumination and lowering of the platform was repeated until Hull
had built up a solid object. He then raised the platform to reveal
his first creation, a blue plastic cup about an inch tall.
Three years later, he revealed his invention to the engineering
world and it was a hit! Hull founded a company called 3D
Systems in California. The field is now known as solid-imaging
and also can be termed three-dimensional printing. You have a
choice of just about any name for this generic machine, which of
course was long anticipated by the usual cast of characters, the
science fiction writers. Those in the solid-imaging field expect
that in the future you”ll be able to download the software to make
all kinds of objects on your home 3-DR. A comb or a plastic doll
should be duck soup to make.
The article mentions a computer-graphics show last summer at
which hundreds of attendees submitted to laser-scanning of their
heads. Each walked away with a two-inch high, very precise
sculpture of their face. Designers from multi-national companies
can e-mail their designs to their counterparts” solid-imaging
machines to turn out models for inspection anywhere in the
world. There are now ink-jet printers that print, not ink, but little
dots of hot plastic that can be built up into 3-D objects. The
machines, which cost about $65,000, have drawn fans in the
jewelry business where they are used to make wax molds in which
to cast the jewelry. Medical applications currently include making
models of such items as heart valves, dentures, and molds for
making replacement parts such as artificial hip joints.
Archaeologists can use X-ray or other techniques to model
images of the skull or other parts of mummies without
unwrapping them.
The future holds the promise of ink-jet printers that will spit out
dots of not just plastic, but combinations of plastic binders with
ceramics or metals that can be fused together to make complex
shapes and compositions of materials. Laser-sculpting can copy
all kinds of objects. Who knows, you might want to have a copy
of the Venus de Milo or the David in your living room? Instead
of going to a foundry with your model to be cast in bronze, you
might just sketch out your object on your computer and then farm
out the software instructions to your local solid-imaging
equivalent of Kinko”s. This assumes you can”t afford your own
home 3-DR.
An unrelated article in the American Chemical Society”s
publication Chemistry last summer may actually eventually blend
in with the above subject. The short abstract of a paper in April
1999 issue of Nature deals with a property known as
superplasticity. This is a pretty simple concept, it just means that
you can stretch a chunk of a material without breaking it, just like
pulling taffy. Brings back memories of the time as a child when
our family lived in Atlantic City. Do they still have salt-water
taffy? But back to superplasticity. Metals and alloys have what
are known as grain structures, which you can see typically by
polishing and/or etching a sample. These grains are essentially
little crystals. Unless you have the rare single crystal (which you
do have in most semiconductor devices), a metal or alloy object is
composed of many grains of various sizes. What has been found
now is that by reducing the size of these grains or microcrystals
down to the nanocrystal size (really, really small crystals), the
same metal or alloy can be pulled without breaking at much lower
temperatures than for the ordinary, larger grain materials.
What amazed me was that a nickel alloy with aluminum was one
that was mentioned in the article. When I was at Bell Labs, I
once foolishly thought that a nickel-aluminum alloy would make a
good electrode material for a battery. I had a sample the size of
my thumb made up and was going to form it into an electrode. It
turned out that sucker was the hardest most unbreakable,
unbendable, unfile-able, uncrushable piece of stuff that I”ve ever
handled. I couldn”t do anything with it. At any rate, these fine-
grain superplastic materials, with their property of superplasticity
at much lower than normal temperatures, result in more
economical fabrication of objects ranging from aircraft turbine
blades to biomedical prosthetic devices.
To sum up, the world of fabricating materials into 3-D objects is
one that is evolving into forms that even the recent plethora of
millennial prognosticators might consider quite revolutionary.
Now if we can find that other universe, maybe there”s still hope
for our future.
Allen F. Bortrum
