Pushing forward, toward manufacturing's future
When the Eads Bridge opened in 1874, the most distinctive living thing to cross it was an elephant. The reason for the “elephant walk” was the structure’s distinctive—and revolutionary—design.
Famed civil engineer James B. Eads designed and built the bridge linking St. Louis and Illinois. It was the longest bridge in the world at the time, and the first to span the Mississippi River. The design called for two spans 502' long and a third 520' long. No bridge had been built with spans that long before. The most extreme design feature, though, was the then-new material specified for the superstructure: steel. No other steel bridge existed.
“Eads’ folly” elicited jeers from bridge builders and raised safety concerns among the general public. To calm the latter group’s fears, Eads had an elephant led across the bridge prior to its opening. The conventional wisdom of the day held that an elephant wouldn’t step on an unstable surface.
The elephant walked calmly onto the bridge and ambled east from St. Louis to the opposite bank. People followed. So, figuratively speaking, did the world’s bridge builders. Eads’ masterpiece instantly and completely transformed bridge design and construction—forever.
While micromanufacturing cannot point to a single advancement that has had the same impact as Eads’ feat, collectively, the micro developments of the past 10 years have profoundly influenced manufacturing.
One example is the family of fabrication processes for mass producing 3-D, monolithic devices with moving parts. Made from multiple materials, they’re designed with complex, micron-sized internal features that would be impossible to produce by conventional means. These processes, the focus of much research the past few years, are used to manufacture everything from cell phone components to microsurgical tools able to enter the human heart and remove damaged tissue.
Other research-intensive areas of micromanufacturing include:
- fluidics, in which submillimeter, multilayer devices move nanoliter volumes of liquid or gas;
- fuel cells, gas turbines and other powerplants (see Cover Story about piezoelectric motors);
- 3-D stacking of microchips, which dramatically increases chip memory capacity and processing speed;
- medical implants and other microscale devices; and
- desktop factories, incorporating turnkey systems that allow microparts to be manufactured outside the plant environment.
A lot of work is being done in the nutsand- bolts areas of micromanufacturing, too. Examples discussed in this issue include improving microEDM dielectric fluids; new carbide grades for microtools; new metrology devices for microparts; and the design of more reliable, productive ultrafast-pulse lasers.
Researchers are also developing everything from more robust, productive micromachines to microscale-specific workholding and parts-handling systems to cutting tools to design software.
Slowly, steadily, these developments are enhancing the way industry manufactures microscale parts. And, similar to the impact James Eads’ structure had on bridge building, the developments occurring now promise to alter the manufacturing landscape forever.