Leu, the Keith and Pat Bailey Missouri Distinguished Professor of Integrated Product Manufacturingat UMR, has an idea for making rapid prototyping -- a means of quickly and inexpensively making models of parts or products -- even more rapid. It involves using ice rather than plastics to create the models. He calls his system "Rapid Freeze Prototyping," or RFP.

"Compared with other prototyping methods, it's cheaper, faster and much cleaner," says Leu. "But it's also very challenging because you must have a controlled environment for the process."

Manufacturers have been using rapid prototyping technologies since the mid-1980s. In its more traditional form, rapid prototyping -- sometimes called "desktop manufacturing" -- involves the fabrication of three-dimensional models, layer by layer, directly from 3-D computer drawings via the aid of a computer-controlled machine. These prototypes typically are made from a polymer resin that is deposited in much the same fashion as the ink from a laser-jet printer is deposited onto a sheet of paper.

Rapid prototypes help manufacturers to better visualize their computerized designs, or to see how well various parts of a proposed product might fit together. The technology allows manufacturers to reduce costs and the time involved in designing and testing new parts or products, Leu says.

"The rapid prototyping technology has helped manufacturers to develop their products more rapidly and at lower costs in the ever changing and more competitive global market," Leu explains.

But most rapid prototyping systems are still too costly, and many of them generate dust or emit smoke, posing health risks. Leu's Rapid Freeze Prototyping would not only be faster -- reducing the time to produce a prototype from days to a matter of hours -- but also cleaner. And because water is cheaper than plastic polymers, the process would be less expensive than traditional rapid prototyping.

How it works

RFP works in a fashion similar to other rapid prototyping techniques. In his Virtual and Rapid Prototyping Laboratory in UMR's Engineering Research Laboratory, Leu has built an experimental system through which droplets of water are deposited from a nozzle onto a surface, just as the plastic material of other systems. Unlike other rapid prototyping techniques, however, this one occurs within a freezing chamber, to keep the fabricated part intact. Moreover, rather than creating the prototype layer by layer, Leu's system first creates a frozen "shell," or boundary, out of ice, then fills the enclosed interior with a steady stream of water that freezes. Creating the boundary first, then filling it, considerably reduces the time involved, Leu says.

Leu admits that his system is still very experimental. But he believes it offers manufacturers a variety of advantages to traditional prototyping systems. Aside from its speed and lower operating costs, the system also would make it easier for manufacturers to build transparent parts, as well as color parts (just add food coloring to the water stream).

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