3-D Printing: How It Works

by Luke Jones  on Monday, Feb. 4, 2013 12:00 am  

George Tebbetts displays a base with a printed object attached. The printer lays molten plastic on the base to build objects.  (Photo by Luke Jones)

To bring an object to life, there first must be a design. Normally this is built on a computer with 3-D modeling software. An object already available in physical space can also be copied using a 3-D scanner.

Once there’s a 3-D model ready, it can be printed. Most 3-D printers construct objects in strong ABS plastic. The plastic comes in strings similar to WeedEater line, and there are two types: support material — which holds the object in place and is removed later — and build material.

A square of foam or plastic goes into the refrigerator-shaped printer. A typical printer’s build space is about 1 cubic foot.

Once the door is closed, the base rises to the top of the chamber and a pair of heated nozzles melts the plastic and squirts it onto the base, alternating between the support and build material.

After squirting one layer of plastic, the base moves down about seven-thousandths of an inch and begins another, placing layer after layer, until the object is complete.

“Some fuse with a laser; others use an oven,” said George Tebbetts, chair of the department of engineering technology at the University of Arkansas at Little Rock. “It’s molten as it comes out of the nozzle. It’s a heated chamber, so when it comes out, it’s at just a point below molten. It will fuse immediately when it comes out of the nozzle; then it’s done.”

The actual printing process isn’t rapid: Depending on the model and project, it can take anywhere from four to 100 or more hours to print.

Once out of the machine, the support material needs to be removed. In some cases, it’s simply broken off the object by hand. In other situations, like at UALR, it’s placed in a tank of slightly alkaline water, which is then heated up to 70 degrees Celsius. The object is left in the tank until the support material dissolves.

See also: 3-D Printers Show Unlimited Potential



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