TransForum, Vol. 2, No. 4

SOLID FREE-FORM FABRICATION: BREAKING THE MOLD

Argonne researchers perfect a technology to speed design and fabrication of vehicle components

Investing in a tooling die is not taken lightly in the transportation industry or in any other manufacturing realm. With the cost of a die typically running from a half to several million dollars, manufacturers want to be sure a design isn't flawed before they quite literally cast it in stone.

Argonne researchers are refining solid free-form fabrication (SFF -- also known as "rapid prototyping") technology to help companies inexpensively reduce the time required to go from design to finished part. Specifications can be adjusted and retested before the design is cast into a costly die.

In die-life extension research for Ford Advanced Manufacturing, Argonne used a Ford-generated CAD file as input for solid free-form fabrication to create the ceramic die insert shown here. The insert is for an injection molding die used to make automotive panels -- it forms one of the instrument cluster holes.

In SFF a finished part "materializes" directly from a computer-generated design file. Specially formulated liquid or solid polymers, ceramics, or metals are deposited, photopolymerized, or laser-sintered to shape the part as directed by a succession of thin cross-sections of the design file. (If no design file exists for a component, Argonne can create one using three-dimensional tomographic imaging.)

The Argonne SFF method uses a sweeping material-feed head that deposits material on an inert surface. In one version, the material is extruded as a high-viscosity material (like toothpaste); in another, tiny droplets are launched by means of technology similar to that of a dot-matrix printer. In a joint research project with Ford Advanced Manufacturing to study the potential for extending a die's life, Argonne used SFF to fabricate a ceramic insert in a high-wear section of a tool. Argonne has also collaborated on SFF projects with Advanced Ceramics Research, Ballistic Particle Machines, Lone Peak Engineering, Midwest Orthopedics, Scientific Measurement Systems, Spectra Group, Stratasys Ltd., and Zimmer Corporation.

In addition to creating prototype parts in hours instead of months, SFF may sometimes eliminate the need for dies by fabricating many parts at once. "Theoretically, a thousand material-feed heads could be attached to one giant SFF system," said Bill Ellingson, leader of Argonne's SFF research.

The implications for distributed manufacturing and remote machining are enormous, Ellingson noted. Designs can be created in one country and beamed by satellite to other parts of the world where the manufacturing takes place.

Significant savings in time and money are important benefits of SFF. But for some applications, such as the emerging field of automotive sensors, SFF may be the best fabrication method because it can yield a uniquely complex finished part. A part created by the deposition of tiny droplets can have a vastly more delicate and convoluted infrastructure than can a molded part. Provided that appropriate materials can be formulated, droplet-deposition SFF may be the best tool available for the manufacture of extremely intricate electronic circuits, especially for applications in which complex sensors would improve automotive controls.

"Argonne's developments in ceramic SFF, and our related ongoing research in sensors, makes us ideally suited for this type of advanced sensor development," Ellingson said. Other U.S. research centers pursuing SFF-formed ceramic materials include Rutgers University, The University of Michigan, and AlliedSignal Corporation's research center.