3D Printing: What a 3D Printer Is and How It Works

An array of additive manufacturing devices at MIT. The U.S. hopes such technology can give a boost to its manufacturing sector.

A 3D printer cannot make any object on demand like the "Star Trek" replicators of science fiction. But a growing array of 3D printing machines has already begun to revolutionize the business of making things in the real world.

3D printers work by following a computer's digital instructions to "print" an object using materials such as plastic, ceramics and metal. The printing process involves building up an object one layer at a time until it's complete. For instance, some 3D printers squirt out a stream of heated, semi-liquid plastic that solidifies as the printer's head moves around to create the outline of each layer within the object.

Manufacturers have quietly used 3D printing technology — also known as additive manufacturing — to build models and prototypes of products over the past 20 years. Charles Hull invented the first commercial 3D printer and offered it for sale through his company 3D Systems in 1986. Hull's machine used stereolithography, a technique that relies upon a laser to solidify an ultraviolet-sensitive polymer material wherever the ultraviolet laser touches.

3D printing probably won't replace many of the usual assembly-line methods for building standard products. Instead, the technology offers the advantage of making individual, specifically tailored parts on demand — something more suited to creating specialized parts for U.S. military aircraft rather than making thousands of trash cans for sale at Wal-Mart. Boeing has already used 3D printing to make more than 22,000 parts used on civilian and military aircraft flying today.

The medical industry has also taken advantage of 3D printing's ability to make unique objects that might otherwise be tough to build using traditional methods. U.S. surgeons implanted a 3D-printed skull piece to replace 75 percent of a patient's skull during an operation in March 2013. Researchers also built a 3D-printed ear mold that served as the framework for a bioengineered ear with living cells.

The spread of 3D printing technology around the world could also shrink geographical distances for both homeowners and businesses. Online marketplaces already allow individuals to upload 3D-printable designs for objects and sell them anywhere in the world. Rather than pay hefty shipping fees and import taxes, sellers can simply arrange for a sold product to be printed at whatever 3D printing facility is closest to the buyer.

Businesses won't be alone in benefiting from 3D printing's print-on-demand-anywhere capability. The U.S. military has deployed 3D printing labs to Afghanistan as a way to speed up the pace of battlefield innovation and rapidly build whatever soldiers might need onsite. NASA has looked into 3D printing for making replacement parts aboard the International Space Station and building spacecraft in orbit.

But 3D printing still has its limits. Most 3D printers can only print objects using a specific type of material — a serious limitation that prevents 3D printers from creating complex objects such as an Apple iPhone. Yet researchers and commercial companies have begun developing workarounds. Optomec, a company based in Albuquerque, New Mexico, has already made a 3D printer capable of printing electronic circuitry onto objects.

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Jeremy has written for publications such as Popular Science, Scientific American Mind and Reader's Digest Asia. He obtained his masters degree in science journalism from New York University, and completed his undergraduate education in the history and sociology of science at the University of Pennsylvania.

3D Printing: What a 3D Printer Is and How It Works

History of 3D printing

Future of 3D printing

Limitations of 3D printing