FITCHBURG, MASS. - Current controls, guiding a tool to cut a curve in a steel mold, move the tool in tiny stair-steps that must be smoothed by hand. But a new generation of controllers —called NURBS — can move the tool in a smooth curve, eliminating the need for hand finishing, according to Fraunhofer Resource Center in Boston. Existing control systems transfer the information, via computer aided manufacturing, as a series of straight lines. That means the tool alternately has to speed up and slow down to make the transition, taking more time and creating the tiny steps on the finished mold.
Hand finishing can alter the mold dimensions slightly, an important factor in making parts with large, smooth surface areas.
NURBS stands for nonuniform rational B splines. The technology takes a computer-aided design of a mold and moves the data directly to the machine tool's controller, said John Teachout, Fraunhofer director of sales, marketing and business development.
Using NURBS avoids the portion of the CAM step that defines the cutter path, Teach-out said in an interview at Fraunhofer's booth during the MassPlastics trade show, held in Fitchburg March 27-28.
It is no secret that computers are driving a revolution. Teachout said that what today seems exotic could become commonplace. Stereolithogra-phy could make full-production molds.
Holographic images could replace expensive clay models used by automakers to design new cars.
``If you could get away from the idea that you had to go down to a model and physically walk around it, and instead look at a holographic model hanging in front of your face, the price of cars would drop,'' Teachout said.