Innovation: Spot check

It takes 4,000 spot welds to hold a car together, but at present the only way to check for defects is to test destructively a random sample of welds. Because manufacturers cannot be sure of finding all faults this way, the number of spot welds is increased for safety.

Now scientists at the Fraunhofer Institute of Non-Destructive Testing, in Germany, have developed an ultrasound system for testing the size and quality of spot welds on the production line.