Sparks shooting from robot welding machines: It's an iconic image of car manufacturing. But at Ford Motor (F ), the shower of sparks is getting less intense -- an indication of a major change in welding.

The computer-modeling methods used to estimate how strong a structural weld should be are notoriously inexact. So the welds for cars, bridges, and pipelines are overengineered to be safe. Now, after a decade-long quest, Pingsha Dong has found a way to trim that fat.

Most experts scoffed when Dong, head of welding research at Battelle Memorial Institute in Columbus, Ohio, unveiled the software in 2000 -- too many such claims had previously flopped. But the technique has won a thumbs-up at Caterpillar (CAT ) and ChevronTexaco (CVX ), and Ford says it will reduce the cost of producing new car bodies by millions of dollars a year.

Edited by Otis Port

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